rfc9275.original   rfc9275.txt 
ALTO K. Gao Internet Engineering Task Force (IETF) K. Gao
Internet-Draft Sichuan University Request for Comments: 9275 Sichuan University
Intended status: Experimental Y. Lee Category: Experimental Y. Lee
Expires: 21 September 2022 Samsung ISSN: 2070-1721 Samsung
S. Randriamasy S. Randriamasy
Nokia Bell Labs Nokia Bell Labs
Y.R. Yang Y. Yang
Yale University Yale University
J. Zhang J. Zhang
Tongji University Tongji University
20 March 2022 August 2022
An ALTO Extension: Path Vector An Extension for Application-Layer Traffic Optimization (ALTO):
draft-ietf-alto-path-vector-25 Path Vector
Abstract Abstract
This document is an extension to the base Application-Layer Traffic This document is an extension to the base Application-Layer Traffic
Optimization (ALTO) protocol. It extends the ALTO Cost Map and ALTO Optimization (ALTO) protocol. It extends the ALTO cost map and ALTO
Property Map services so that an application can decide which property map services so that an application can decide to which
endpoint(s) to connect based on not only numerical/ordinal cost endpoint(s) to connect based not only on numerical/ordinal cost
values but also fine-grained abstract information of the paths. This values but also on fine-grained abstract information regarding the
is useful for applications whose performance is impacted by specified paths. This is useful for applications whose performance is impacted
components of a network on the end-to-end paths, e.g., they may infer by specific components of a network on the end-to-end paths, e.g.,
that several paths share common links and prevent traffic bottlenecks they may infer that several paths share common links and prevent
by avoiding such paths. This extension introduces a new abstraction traffic bottlenecks by avoiding such paths. This extension
called Abstract Network Element (ANE) to represent these components introduces a new abstraction called the "Abstract Network Element"
and encodes a network path as a vector of ANEs. Thus, it provides a (ANE) to represent these components and encodes a network path as a
more complete but still abstract graph representation of the vector of ANEs. Thus, it provides a more complete but still abstract
underlying network(s) for informed traffic optimization among graph representation of the underlying network(s) for informed
endpoints. traffic optimization among endpoints.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This document is not an Internet Standards Track specification; it is
provisions of BCP 78 and BCP 79. published for examination, experimental implementation, and
evaluation.
Internet-Drafts are working documents of the Internet Engineering This document defines an Experimental Protocol for the Internet
Task Force (IETF). Note that other groups may also distribute community. This document is a product of the Internet Engineering
working documents as Internet-Drafts. The list of current Internet- Task Force (IETF). It represents the consensus of the IETF
Drafts is at https://datatracker.ietf.org/drafts/current/. community. It has received public review and has been approved for
publication by the Internet Engineering Steering Group (IESG). Not
all documents approved by the IESG are candidates for any level of
Internet Standard; see Section 2 of RFC 7841.
Internet-Drafts are draft documents valid for a maximum of six months Information about the current status of this document, any errata,
and may be updated, replaced, or obsoleted by other documents at any and how to provide feedback on it may be obtained at
time. It is inappropriate to use Internet-Drafts as reference https://www.rfc-editor.org/info/rfc9275.
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 21 September 2022.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction
2. Requirements Languages . . . . . . . . . . . . . . . . . . . 6 2. Requirements Language
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Terminology
4. Requirements and Use Cases . . . . . . . . . . . . . . . . . 7 4. Requirements and Use Cases
4.1. Design Requirements . . . . . . . . . . . . . . . . . . . 7 4.1. Design Requirements
4.2. Sample Use Cases . . . . . . . . . . . . . . . . . . . . 10 4.2. Sample Use Cases
4.2.1. Exposing Network Bottlenecks . . . . . . . . . . . . 11 4.2.1. Exposing Network Bottlenecks
4.2.2. Resource Exposure for CDN and Service Edge . . . . . 15 4.2.2. Resource Exposure for CDNs and Service Edges
5. Path Vector Extension: Overview . . . . . . . . . . . . . . . 17 5. Path Vector Extension: Overview
5.1. Abstract Network Element (ANE) . . . . . . . . . . . . . 18 5.1. Abstract Network Element (ANE)
5.1.1. ANE Entity Domain . . . . . . . . . . . . . . . . . . 19 5.1.1. ANE Entity Domain
5.1.2. Ephemeral and Persistent ANEs . . . . . . . . . . . . 19 5.1.2. Ephemeral and Persistent ANEs
5.1.3. Property Filtering . . . . . . . . . . . . . . . . . 20 5.1.3. Property Filtering
5.2. Path Vector Cost Type . . . . . . . . . . . . . . . . . . 20 5.2. Path Vector Cost Type
5.3. Multipart Path Vector Response . . . . . . . . . . . . . 21 5.3. Multipart Path Vector Response
5.3.1. Identifying the Media Type of the Root Object . . . . 22 5.3.1. Identifying the Media Type of the Object Root
5.3.2. References to Part Messages . . . . . . . . . . . . . 22 5.3.2. References to Part Messages
6. Specification: Basic Data Types . . . . . . . . . . . . . . . 23 6. Specification: Basic Data Types
6.1. ANE Name . . . . . . . . . . . . . . . . . . . . . . . . 23 6.1. ANE Name
6.2. ANE Entity Domain . . . . . . . . . . . . . . . . . . . . 23 6.2. ANE Entity Domain
6.2.1. Entity Domain Type . . . . . . . . . . . . . . . . . 23 6.2.1. Entity Domain Type
6.2.2. Domain-Specific Entity Identifier . . . . . . . . . . 23 6.2.2. Domain-Specific Entity Identifier
6.2.3. Hierarchy and Inheritance . . . . . . . . . . . . . . 23 6.2.3. Hierarchy and Inheritance
6.2.4. Media Type of Defining Resource . . . . . . . . . . . 23 6.2.4. Media Type of Defining Resource
6.3. ANE Property Name . . . . . . . . . . . . . . . . . . . . 24 6.3. ANE Property Name
6.4. Initial ANE Property Types . . . . . . . . . . . . . . . 24 6.4. Initial ANE Property Types
6.4.1. Maximum Reservable Bandwidth . . . . . . . . . . . . 24 6.4.1. Maximum Reservable Bandwidth
6.4.2. Persistent Entity ID . . . . . . . . . . . . . . . . 25 6.4.2. Persistent Entity ID
6.4.3. Examples . . . . . . . . . . . . . . . . . . . . . . 25 6.4.3. Examples
6.5. Path Vector Cost Type . . . . . . . . . . . . . . . . . . 26 6.5. Path Vector Cost Type
6.5.1. Cost Metric: ane-path . . . . . . . . . . . . . . . . 26 6.5.1. Cost Metric: "ane-path"
6.5.2. Cost Mode: array . . . . . . . . . . . . . . . . . . 27 6.5.2. Cost Mode: "array"
6.6. Part Resource ID and Part Content ID . . . . . . . . . . 27 6.6. Part Resource ID and Part Content ID
7. Specification: Service Extensions . . . . . . . . . . . . . . 27 7. Specification: Service Extensions
7.1. Notations . . . . . . . . . . . . . . . . . . . . . . . . 27 7.1. Notation
7.2. Multipart Filtered Cost Map for Path Vector . . . . . . . 28 7.2. Multipart Filtered Cost Map for Path Vector
7.2.1. Media Type . . . . . . . . . . . . . . . . . . . . . 28 7.2.1. Media Type
7.2.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . 28 7.2.2. HTTP Method
7.2.3. Accept Input Parameters . . . . . . . . . . . . . . . 28 7.2.3. Accept Input Parameters
7.2.4. Capabilities . . . . . . . . . . . . . . . . . . . . 29 7.2.4. Capabilities
7.2.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . 30 7.2.5. Uses
7.2.6. Response . . . . . . . . . . . . . . . . . . . . . . 30 7.2.6. Response
7.3. Multipart Endpoint Cost Service for Path Vector . . . . . 34 7.3. Multipart Endpoint Cost Service for Path Vector
7.3.1. Media Type . . . . . . . . . . . . . . . . . . . . . 34 7.3.1. Media Type
7.3.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . 34 7.3.2. HTTP Method
7.3.3. Accept Input Parameters . . . . . . . . . . . . . . . 34 7.3.3. Accept Input Parameters
7.3.4. Capabilities . . . . . . . . . . . . . . . . . . . . 35 7.3.4. Capabilities
7.3.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . 35 7.3.5. Uses
7.3.6. Response . . . . . . . . . . . . . . . . . . . . . . 35 7.3.6. Response
8. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 39 8. Examples
8.1. Sample Setup . . . . . . . . . . . . . . . . . . . . . . 39 8.1. Sample Setup
8.2. Information Resource Directory . . . . . . . . . . . . . 39 8.2. Information Resource Directory
8.3. Multipart Filtered Cost Map . . . . . . . . . . . . . . . 42 8.3. Multipart Filtered Cost Map
8.4. Multipart Endpoint Cost Service Resource . . . . . . . . 43 8.4. Multipart Endpoint Cost Service Resource
8.5. Incremental Updates . . . . . . . . . . . . . . . . . . . 48 8.5. Incremental Updates
8.6. Multi-cost . . . . . . . . . . . . . . . . . . . . . . . 50 8.6. Multi-Cost
9. Compatibility with Other ALTO Extensions . . . . . . . . . . 52 9. Compatibility with Other ALTO Extensions
9.1. Compatibility with Legacy ALTO Clients/Servers . . . . . 53 9.1. Compatibility with Legacy ALTO Clients/Servers
9.2. Compatibility with Multi-Cost Extension . . . . . . . . . 53 9.2. Compatibility with Multi-Cost Extension
9.3. Compatibility with Incremental Update . . . . . . . . . . 53 9.3. Compatibility with Incremental Update Extension
9.4. Compatibility with Cost Calendar . . . . . . . . . . . . 53 9.4. Compatibility with Cost Calendar Extension
10. General Discussions . . . . . . . . . . . . . . . . . . . . . 54 10. General Discussion
10.1. Constraint Tests for General Cost Types . . . . . . . . 54 10.1. Constraint Tests for General Cost Types
10.2. General Multi-Resource Query . . . . . . . . . . . . . . 54 10.2. General Multi-Resource Query
11. Security Considerations . . . . . . . . . . . . . . . . . . . 55 11. Security Considerations
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 57 12. IANA Considerations
12.1. ALTO Cost Metric Registry . . . . . . . . . . . . . . . 57 12.1. "ALTO Cost Metrics" Registry
12.2. ALTO Cost Mode Registry . . . . . . . . . . . . . . . . 58 12.2. "ALTO Cost Modes" Registry
12.3. ALTO Entity Domain Type Registry . . . . . . . . . . . . 58 12.3. "ALTO Entity Domain Types" Registry
12.4. ALTO Entity Property Type Registry . . . . . . . . . . . 59 12.4. "ALTO Entity Property Types" Registry
12.4.1. New ANE Property Type: Maximum Reservable 12.4.1. New ANE Property Type: Maximum Reservable Bandwidth
Bandwidth . . . . . . . . . . . . . . . . . . . . . . 59 12.4.2. New ANE Property Type: Persistent Entity ID
12.4.2. New ANE Property Type: Persistent Entity ID . . . . 60 13. References
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 60 13.1. Normative References
13.1. Normative References . . . . . . . . . . . . . . . . . . 60 13.2. Informative References
13.2. Informative References . . . . . . . . . . . . . . . . . 61 Acknowledgments
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 64 Authors' Addresses
Appendix B. Revision Logs (To be removed before publication) . . 64
B.1. Changes since -20 . . . . . . . . . . . . . . . . . . . . 64
B.2. Changes since -19 . . . . . . . . . . . . . . . . . . . . 65
B.3. Changes since -18 . . . . . . . . . . . . . . . . . . . . 65
B.4. Changes since -17 . . . . . . . . . . . . . . . . . . . . 65
B.5. Changes since -16 . . . . . . . . . . . . . . . . . . . . 65
B.6. Changes since -15 . . . . . . . . . . . . . . . . . . . . 65
B.7. Changes since -14 . . . . . . . . . . . . . . . . . . . . 65
B.8. Changes since -13 . . . . . . . . . . . . . . . . . . . . 66
B.9. Changes since -12 . . . . . . . . . . . . . . . . . . . . 66
B.10. Changes since -11 . . . . . . . . . . . . . . . . . . . . 66
B.11. Changes since -10 . . . . . . . . . . . . . . . . . . . . 66
B.12. Changes since -09 . . . . . . . . . . . . . . . . . . . . 67
B.13. Changes since -08 . . . . . . . . . . . . . . . . . . . . 67
B.14. Changes Since Version -06 . . . . . . . . . . . . . . . . 67
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 68
1. Introduction 1. Introduction
Network performance metrics are crucial to assess the Quality of Network performance metrics are crucial for assessing the Quality of
Experience (QoE) of applications. The ALTO protocol allows Internet Experience (QoE) of applications. The Application-Layer Traffic
Service Providers (ISPs) to provide guidance, such as topological Optimization (ALTO) protocol allows Internet Service Providers (ISPs)
distance between different end hosts, to overlay applications. Thus, to provide guidance, such as topological distances between different
the overlay applications can potentially improve the perceived QoE by end hosts, to overlay applications. Thus, the overlay applications
better orchestrating their traffic to utilize the resources in the can potentially improve the perceived QoE by better orchestrating
underlying network infrastructure. their traffic to utilize the resources in the underlying network
infrastructure.
Existing ALTO Cost Map (Section 11.2.3 of [RFC7285]) and Endpoint The existing ALTO cost map (Section 11.2.3 of [RFC7285]) and Endpoint
Cost Service (Section 11.5 of [RFC7285]) provide only cost Cost Service (Section 11.5 of [RFC7285]) provide only cost
information on an end-to-end path defined by its <source, information for an end-to-end path defined by its <source,
destination> endpoints: The base protocol [RFC7285] allows the destination> endpoints: the base protocol [RFC7285] allows the
services to expose the topological distances of end-to-end paths, services to expose the topological distances of end-to-end paths,
while various extensions have been proposed to extend the capability while various extensions have been proposed to extend the capability
of these services, e.g., to express other performance metrics of these services, e.g., to express other performance metrics
[I-D.ietf-alto-performance-metrics], to query multiple costs [ALTO-PERF-METRICS], to query multiple costs simultaneously
simultaneously [RFC8189], and to obtain the time-varying values [RFC8189], and to obtain time-varying values [RFC8896].
[RFC8896].
While the existing extensions are sufficient for many overlay While numerical/ordinal cost values for end-to-end paths provided by
applications, the QoE of some overlay applications depends not only the existing extensions are sufficient to optimize the QoE of many
on the cost information of end-to-end paths, but also on particular overlay applications, the QoE of some overlay applications also
components of a network on the paths and their properties. For depends on the properties of particular components on the paths. For
example, job completion time, which is an important QoE metric for a example, job completion time, which is an important QoE metric for a
large-scale data analytics application, is impacted by shared large-scale data analytics application, is impacted by shared
bottleneck links inside the carrier network as link capacity may bottleneck links inside the carrier network, as link capacity may
impact the rate of data input/output to the job. We refer to such impact the rate of data input/output to the job. We refer to such
components of a network as Abstract Network Elements (ANE). components of a network as Abstract Network Elements (ANEs).
Predicting such information can be very complex without the help of Predicting such information can be very complex without the help of
ISPs, for example, [BOXOPT] has shown that finding the optimal ISPs; for example, [BOXOPT] has shown that finding the optimal
bandwidth reservation for multiple flows can be NP-hard without bandwidth reservation for multiple flows can be NP-hard without
further information than whether a reservation succeeds. With proper further information than whether a reservation succeeds. With proper
guidance from the ISP, an overlay application may be able to schedule guidance from the ISP, an overlay application may be able to schedule
its traffic for better QoE. In the meantime, it may be helpful as its traffic for better QoE. In the meantime, it may be helpful as
well for ISPs if applications could avoid using bottlenecks or well for ISPs if applications could avoid using bottlenecks or
challenging the network with poorly scheduled traffic. challenging the network with poorly scheduled traffic.
Despite the claimed benefits, ISPs are not likely to expose raw Despite the claimed benefits, ISPs are not likely to expose raw
details on their network paths: first for the sake of topology hiding details on their network paths: first because ISPs have requirements
requirement, second because it may increase volume and computation to hide their network topologies, second because these details may
overhead, and last because applications do not necessarily need all increase volume and computation overhead, and last because
the network path details and are likely not able to understand them. applications do not necessarily need all the network path details and
are likely not able to understand them.
Therefore, it is beneficial for both ISPs and applications if an ALTO Therefore, it is beneficial for both ISPs and applications if an ALTO
server provides ALTO clients with an "abstract network state" that server provides ALTO clients with an "abstract network state" that
provides the necessary information to applications, while hiding the provides the necessary information to applications, while hiding
network complexity and confidential information. An "abstract network complexity and confidential information. An "abstract
network state" is a selected set of abstract representations of network state" is a selected set of abstract representations of ANEs
Abstract Network Elements traversed by the paths between <source, traversed by the paths between <source, destination> pairs combined
destination> pairs combined with properties of these Abstract Network with properties of these ANEs that are relevant to the overlay
Elements that are relevant to the overlay applications' QoE. Both an applications' QoE. Both an application via its ALTO client and the
application via its ALTO client and the ISP via the ALTO server can ISP via the ALTO server can achieve better confidentiality and
achieve better confidentiality and resource utilization by resource utilization by appropriately abstracting relevant ANEs.
appropriately abstracting relevant Abstract Network Elements. Server Server scalability can also be improved by combining ANEs and their
scalability can also be improved by combining Abstract Network properties in a single response.
Elements and their properties in a single response.
This document extends [RFC7285] to allow an ALTO server to convey This document extends the ALTO base protocol [RFC7285] to allow an
"abstract network state", for paths defined by their <source, ALTO server to convey "abstract network state" for paths defined by
destination> pairs. To this end, it introduces a new cost type their <source, destination> pairs. To this end, it introduces a new
called "Path Vector" following the cost metric registration specified cost type called a "Path Vector", following the cost metric
in [RFC7285] and the updated cost mode registration specified in registration specified in [RFC7285] and the updated cost mode
[I-D.bw-alto-cost-mode]. A Path Vector is an array of identifiers registration specified in [RFC9274]. A Path Vector is an array of
that identifies an Abstract Network Element, which can be associated identifiers that identifies an ANE, which can be associated with
with various properties. The associations between ANEs and their various properties. The associations between ANEs and their
properties are encoded in an ALTO information resource called Unified properties are encoded in an ALTO information resource called the
Property Map, which is specified in "entity property map", which is specified in [RFC9240].
[I-D.ietf-alto-unified-props-new].
For better confidentiality, this document aims to minimize For better confidentiality, this document aims to minimize
information exposure of an ALTO server when providing Path Vector information exposure of an ALTO server when providing Path Vector
service. In particular, this document enables and recommends that services. In particular, this document enables the capability, and
first ANEs are constructed on demand, and second an ANE is only also recommends that 1) ANEs be constructed on demand and 2) an ANE
associated with properties that are requested by an ALTO client. A only be associated with properties that are requested by an ALTO
Path Vector response involves two ALTO Maps: the Cost Map that client. A Path Vector response involves two ALTO maps: the cost map,
contains the Path Vector results and the up-to-date Unified Property which contains the Path Vector results; and the up-to-date entity
Map that contains the properties requested for these ANEs. To property map, which contains the properties requested for these ANEs.
enforce consistency and improve server scalability, this document To enforce consistency and improve server scalability, this document
uses the "multipart/related" content type defined in [RFC2387] to uses the "multipart/related" content type as defined in [RFC2387] to
return the two maps in a single response. return the two maps in a single response.
As a single ISP may not have the knowledge of the full Internet paths As a single ISP may not have knowledge of the full Internet paths
between arbitrary endpoints, this document is mainly applicable 1) between arbitrary endpoints, this document is mainly applicable when
when there is a single ISP between the requested source and
destination PIDs or endpoints, for example, ISP-hosted CDN/edge,
tenant interconnection in a single public cloud platform, etc.; or 2)
when the Path Vectors are generated from end-to-end measurement data.
2. Requirements Languages * there is a single ISP between the requested source and destination
Provider-defined Identifiers (PIDs) or endpoints -- for example,
ISP-hosted Content Delivery Network (CDN) / edge, tenant
interconnection in a single public cloud platform, etc., or
* the Path Vectors are generated from end-to-end measurement data.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
When the words appear in lower case, they are to be interpreted with
their natural language meanings.
3. Terminology 3. Terminology
This document extends the ALTO base protocol [RFC7285] and the This document extends the ALTO base protocol [RFC7285] and the entity
Unified Property Map extension [I-D.ietf-alto-unified-props-new]. In property map extension [RFC9240]. In addition to the terms defined
addition to the terms defined in these documents, this document also in those documents, this document also uses the following terms:
uses the following additional terms:
Abstract Network Element (ANE): An abstract representation for a Abstract Network Element (ANE): An abstract representation for a
component in a network that handles data packets and whose component in a network that handles data packets and whose
properties can potentially have an impact on the end-to-end properties can potentially have an impact on the end-to-end
performance of traffic. An ANE can be a physical device such as a performance of traffic. An ANE can be a physical device such as a
router, a link or an interface, or an aggregation of devices such router, a link, or an interface; or an aggregation of devices such
as a subnetwork or a data center. as a subnetwork or a data center.
The definition of Abstract Network Element is similar to Network The definition of an ANE is similar to that for a network element
Element defined in [RFC2216] in the sense that they both provide as defined in [RFC2216] in the sense that they both provide an
an abstract representation of specific components of a network. abstract representation of specific components of a network.
However, they have different criteria on how these particular However, they have different criteria on how these particular
components are selected. Specifically, a Network Element requires components are selected. Specifically, a network element requires
the components to be capable of exercising QoS control, while the components to be capable of exercising QoS control, while an
Abstract Network Element only requires the components to have an ANE only requires the components to have an impact on end-to-end
impact on the end-to-end performance. performance.
ANE Name: A string that uniquely identifies an ANE in a specific ANE name: A string that uniquely identifies an ANE in a specific
scope. An ANE can be constructed either statically in advance or scope. An ANE can be constructed either statically in advance or
on demand based on the requested information. Thus, different on demand based on the requested information. Thus, different
ANEs may only be valid within a particular scope, either ephemeral ANEs may only be valid within a particular scope, either ephemeral
or persistent. Within each scope, an ANE is uniquely identified or persistent. Within each scope, an ANE is uniquely identified
by an ANE Name, as defined in Section 6.1. Note that an ALTO by an ANE name, as defined in Section 6.1. Note that an ALTO
client must not assume ANEs in different scopes but with the same client must not assume ANEs in different scopes but with the same
ANE Name refer to the same component(s) of the network. ANE name refer to the same component(s) of the network.
Path Vector: Path Vector, or ANE Path Vector, refers to a JSON array Path Vector (or ANE Path Vector): Refers to a JSON array of ANE
of ANE Names. It is a generalization of BGP path vector. While names. It is a generalization of a BGP path vector. While a
standard BGP path vector (Section 5.1.2 of [RFC4271]) specifies a standard BGP path vector (Section 5.1.2 of [RFC4271]) specifies a
sequence of autonomous systems for a destination IP prefix, the sequence of Autonomous Systems (ASes) for a destination IP prefix,
Path Vector defined in this extension specifies a sequence of ANEs the Path Vector defined in this extension specifies a sequence of
either for a source Provider-Defined Identifier (PID) and a ANEs for either 1) a source PID and a destination PID, as in the
destination PID as in the CostMapData (11.2.3.6 in [RFC7285]), or CostMapData object (Section 11.2.3.6 of [RFC7285]) or 2) a source
for a source endpoint and a destination endpoint as in the endpoint and a destination endpoint, as in the EndpointCostMapData
EndpointCostMapData object (Section 11.5.1.6 of [RFC7285]). object (Section 11.5.1.6 of [RFC7285]).
Path Vector resource: An ALTO information resource (Section 8.1 of Path Vector resource: An ALTO information resource (Section 8.1 of
[RFC7285]) which supports the extension defined in this document. [RFC7285]) that supports the extension defined in this document.
Path Vector cost type: A special cost type, which is specified in Path Vector cost type: A special cost type, which is specified in
Section 6.5. When this cost type is present in an IRD entry, it Section 6.5. When this cost type is present in an Information
indicates that the information resource is a Path Vector resource. Resource Directory (IRD) entry, it indicates that the information
When this cost type is present in a Filtered Cost Map request or resource is a Path Vector resource. When this cost type is
an Endpoint Cost Service request, it indicates each cost value present in a filtered cost map request or an Endpoint Cost Service
must be interpreted as a Path Vector. request, it indicates that each cost value must be interpreted as
a Path Vector.
Path Vector request: The POST message sent to an ALTO Path Vector Path Vector request: The POST message sent to an ALTO Path Vector
resource. resource.
Path Vector response: A Path Vector response refers to the Path Vector response: Refers to the multipart/related message
multipart/related message returned by a Path Vector resource. returned by a Path Vector resource.
4. Requirements and Use Cases 4. Requirements and Use Cases
4.1. Design Requirements 4.1. Design Requirements
This section gives an illustrative example of how an overlay This section gives an illustrative example of how an overlay
application can benefit from the extension defined in this document. application can benefit from the extension defined in this document.
Assume that an application has control over a set of flows, which may Assume that an application has control over a set of flows, which may
go through shared links/nodes and share bottlenecks. The application go through shared links/nodes and share bottlenecks. The application
seeks to schedule the traffic among multiple flows to get better seeks to schedule the traffic among multiple flows to get better
performance. The constraints of feasible rate allocations of those performance. The constraints of feasible rate allocations of those
flows will benefit the scheduling. However, Cost Maps as defined in flows will benefit the scheduling. However, cost maps as defined in
[RFC7285] can not reveal such information. [RFC7285] cannot reveal such information.
Specifically, consider a network as shown in Figure 1. The network Specifically, consider the example network shown in Figure 1. The
has 7 switches (sw1 to sw7) forming a dumb-bell topology. Switches network has seven switches ("sw1" to "sw7") forming a dumbbell
"sw1", "sw2", "sw3" and "sw4" are access switches, and sw5-sw7 form topology. Switches "sw1", "sw2", "sw3", and "sw4" are access
the backbone. End hosts eh1 to eh4 are connected to access switches switches, and "sw5-sw7" form the backbone. End hosts "eh1" to "eh4"
sw1 to sw4 respectively. Assume that the bandwidth of link eh1 -> are connected to access switches "sw1" to "sw4", respectively.
sw1 and link sw1 -> sw5 is 150 Mbps, and the bandwidth of the other Assume that the bandwidth of link "eh1 -> sw1" and link "sw1 -> sw5"
links is 100 Mbps. is 150 Mbps and the bandwidth of the other links is 100 Mbps.
+-----+ +-----+
| | | |
--+ sw6 +-- --+ sw6 +--
/ | | \ / | | \
PID1 +-----+ / +-----+ \ +-----+ PID2 PID1 +-----+ / +-----+ \ +-----+ PID2
eh1__| |_ / \ ____| |__eh2 eh1__| |_ / \ ____| |__eh2
192.0.2.2 | sw1 | \ +--|--+ +--|--+ / | sw2 | 192.0.2.3 192.0.2.2 | sw1 | \ +--|--+ +--|--+ / | sw2 | 192.0.2.3
+-----+ \ | | | |/ +-----+ +-----+ \ | | | |/ +-----+
\_| sw5 +---------+ sw7 | \_| sw5 +---------+ sw7 |
skipping to change at page 8, line 35 skipping to change at line 350
+-----+ +-----+ +-----+ +-----+
bw(eh1--sw1) = bw(sw1--sw5) = 150 Mbps bw(eh1--sw1) = bw(sw1--sw5) = 150 Mbps
bw(eh2--sw2) = bw(eh3--sw3) = bw(eh4--sw4) = 100 Mbps bw(eh2--sw2) = bw(eh3--sw3) = bw(eh4--sw4) = 100 Mbps
bw(sw1--sw5) = bw(sw3--sw5) = bw(sw2--sw7) = bw(sw4--sw7) = 100 Mbps bw(sw1--sw5) = bw(sw3--sw5) = bw(sw2--sw7) = bw(sw4--sw7) = 100 Mbps
bw(sw5--sw6) = bw(sw5--sw7) = bw(sw6--sw7) = 100 Mbps bw(sw5--sw6) = bw(sw5--sw7) = bw(sw6--sw7) = 100 Mbps
Figure 1: Raw Network Topology Figure 1: Raw Network Topology
The base ALTO topology abstraction of the network is shown in The base ALTO topology abstraction of the network is shown in
Figure 2. Assume the cost map returns an hypothetical cost type Figure 2. Assume that the cost map returns a hypothetical cost type
representing the available bandwidth between a source and a representing the available bandwidth between a source and a
destination. destination.
+----------------------+ +----------------------+
{eh1} | | {eh2} {eh1} | | {eh2}
PID1 | | PID2 PID1 | | PID2
+------+ +------+ +------+ +------+
| | | |
| | | |
{eh3} | | {eh4} {eh3} | | {eh4}
PID3 | | PID4 PID3 | | PID4
+------+ +------+ +------+ +------+
| | | |
+----------------------+ +----------------------+
Figure 2: Base Topology Abstraction Figure 2: Base Topology Abstraction
Now assume the application wants to maximize the total rate of the Now, assume that the application wants to maximize the total rate of
traffic among a set of <source, destination> pairs, say "eh1 -> eh2" the traffic among a set of <source, destination> pairs -- say, "eh1
and "eh1 -> eh4". Let "x" denote the transmission rate of "eh1 -> -> eh2" and "eh1 -> eh4". Let "x" denote the transmission rate of
eh2" and "y" denote the rate of "eh1 -> eh4". The objective function "eh1 -> eh2" and "y" denote the rate of "eh1 -> eh4". The objective
is function is
max(x + y). max(x + y).
With the ALTO Cost Map, the cost between PID1 and PID2 and between With the ALTO cost map, the costs between PID1 and PID2 and between
PID1 and PID4 will both be 100 Mbps. The client can get a capacity PID1 and PID4 will both be 100 Mbps. The client can get a capacity
region of region of
x <= 100 Mbps, x <= 100 Mbps
y <= 100 Mbps. y <= 100 Mbps.
With this information, the client may mistakenly think it can achieve With this information, the client may mistakenly think it can achieve
a maximum total rate of 200 Mbps. However, this rate is infeasible, a maximum total rate of 200 Mbps. However, this rate is infeasible,
as there are only two potential cases: as there are only two potential cases:
* Case 1: "eh1 -> eh2" and "eh1 -> eh4" take different path segments Case 1: "eh1 -> eh2" and "eh1 -> eh4" take different path segments
from "sw5" to "sw7". For example, if "eh1 -> eh2" uses path "eh1 from "sw5" to "sw7". For example, if "eh1 -> eh2" uses path "eh1
-> sw1 -> sw5 -> sw6 -> sw7 -> sw2 -> eh2" and "eh1 -> eh4" uses -> sw1 -> sw5 -> sw6 -> sw7 -> sw2 -> eh2" and "eh1 -> eh4" uses
path "eh1 -> sw1 -> sw5 -> sw7 -> sw4 -> eh4", then the shared path "eh1 -> sw1 -> sw5 -> sw7 -> sw4 -> eh4", then the shared
bottleneck links are "eh1 -> sw1" and "sw1 -> sw5". In this case, bottleneck links are "eh1 -> sw1" and "sw1 -> sw5". In this case,
the capacity region is: the capacity region is:
x <= 100 Mbps x <= 100 Mbps
y <= 100 Mbps y <= 100 Mbps
x + y <= 150 Mbps x + y <= 150 Mbps
and the real optimal total rate is 150 Mbps. and the real optimal total rate is 150 Mbps.
* Case 2: "eh1 -> eh2" and "eh1 -> eh4" take the same path segment Case 2: "eh1 -> eh2" and "eh1 -> eh4" take the same path segment
from "sw5" to "sw7". For example, if "eh1 -> eh2" uses path "eh1 from "sw5" to "sw7". For example, if "eh1 -> eh2" uses path "eh1
-> sw1 -> sw5 -> sw7 -> sw2 -> eh2" and "eh1 -> eh4" also uses -> sw1 -> sw5 -> sw7 -> sw2 -> eh2" and "eh1 -> eh4" also uses
path "eh1 -> sw1 -> sw5 -> sw7 -> sw4 -> eh4", then the shared path "eh1 -> sw1 -> sw5 -> sw7 -> sw4 -> eh4", then the shared
bottleneck link is "sw5 -> sw7". In this case, the capacity bottleneck link is "sw5 -> sw7". In this case, the capacity
region is: region is:
x <= 100 Mbps x <= 100 Mbps
y <= 100 Mbps y <= 100 Mbps
x + y <= 100 Mbps x + y <= 100 Mbps
and the real optimal total rate is 100 Mbps. and the real optimal total rate is 100 Mbps.
Clearly, with more accurate and fine-grained information, the Clearly, with more accurate and fine-grained information, the
application can gain a better prediction of its traffic and may application can better predict its traffic and may orchestrate its
orchestrate its resources accordingly. However, to provide such resources accordingly. However, to provide such information, the
information, the network needs to expose abstract information beyond network needs to expose abstract information beyond the simple cost
the simple cost map abstraction. In particular: map abstraction. In particular:
* The ALTO server must expose abstract information about the network * The ALTO server must expose abstract information about the network
paths that are traversed by the traffic between a source and a paths that are traversed by the traffic between a source and a
destination beyond a simple numerical value, which allows the destination beyond a simple numerical value, which allows the
overlay application to distinguish between Cases 1 and 2 and to overlay application to distinguish between Cases 1 and 2 and to
compute the optimal total rate accordingly. compute the optimal total rate accordingly.
* The ALTO server must allow the client to distinguish the common * The ALTO server must allow the client to distinguish the common
ANE shared by "eh1 -> eh2" and "eh1 -> eh4", e.g., "eh1 - sw1" and ANE shared by "eh1 -> eh2" and "eh1 -> eh4", e.g., "eh1--sw1" and
"sw1 - sw5" in Case 1. "sw1--sw5" in Case 1.
* The ALTO server must expose abstract information on the properties * The ALTO server must expose abstract information on the properties
of the ANEs used by "eh1 -> eh2" and "eh1 -> eh4". For example, of the ANEs used by "eh1 -> eh2" and "eh1 -> eh4". For example,
an ALTO server can either expose the available bandwidth between an ALTO server can either expose the available bandwidth between
"eh1 - sw1", "sw1 - sw5", "sw5 - sw7", "sw5 - sw6", "sw6 - sw7", "eh1--sw1", "sw1--sw5", "sw5--sw7", "sw5--sw6", "sw6--sw7",
"sw7 - sw2", "sw7 - sw4", "sw2 - eh2", "sw4 - eh4" in Case 1, or "sw7--sw2", "sw7--sw4", "sw2--eh2", "sw4--eh4" in Case 1 or expose
expose 3 abstract elements "A", "B" and "C", which represent the three abstract elements "A", "B", and "C", which represent the
linear constraints that define the same capacity region in Case 1. linear constraints that define the same capacity region in Case 1.
In general, we can conclude that to support the multiple flow In general, we can conclude that to support the use case for multiple
scheduling use case, the ALTO framework must be extended to satisfy flow scheduling, the ALTO framework must be extended to satisfy the
the following additional requirements: following additional requirements (ARs):
AR1: An ALTO server must provide the ANEs that are important to AR1: An ALTO server must provide the ANEs that are important for
assess the QoE of the overlay application on the path of a assessing the QoE of the overlay application on the path of a
<source, destination> pair. <source, destination> pair.
AR2: An ALTO server must provide information to identify how ANEs AR2: An ALTO server must provide information to identify how ANEs
are shared on the paths of different <source, destination> pairs. are shared on the paths of different <source, destination> pairs.
AR3: An ALTO server must provide information on the properties that AR3: An ALTO server must provide information on the properties that
are important to assess the QoE of the application for ANEs. are important for assessing the QoE of the application for ANEs.
The extension defined in this document specifies a solution to expose The extension defined in this document specifies a solution to expose
such abstract information. such abstract information.
4.2. Sample Use Cases 4.2. Sample Use Cases
While the multiple flow scheduling problem is used to help identify While the problem related to multiple flow scheduling is used to help
the additional requirements, the extension defined in this document identify the additional requirements, the extension defined in this
can be applied to a wide range of applications. This section document can be applied to a wide range of applications. This
highlights some use cases that are reported. section highlights some of the reported use cases.
4.2.1. Exposing Network Bottlenecks 4.2.1. Exposing Network Bottlenecks
An important use case of the Path Vector extension is to expose One important use case for the Path Vector extension is to expose
network bottlenecks. Applications which need to perform large scale network bottlenecks. Applications that need to perform large-scale
data transfers can benefit from being aware of the resource data transfers can benefit from being aware of the resource
constraints exposed by this extension even if they have different constraints exposed by this extension even if they have different
objectives. One such example is the Worldwide LHC Computing Grid objectives. One such example is the Worldwide LHC Computing Grid
(WLCG), the largest example of a distributed computation (WLCG) (where "LHC" means "Large Hadron Collider"), which is the
collaboration in the research and education world. largest example of a distributed computation collaboration in the
research and education world.
Figure 3 illustrates an example of using ALTO Path Vector as an Figure 3 illustrates an example of using an ALTO Path Vector as an
interface between the job optimizer for a data analytics system and interface between the job optimizer for a data analytics system and
the network manager. In particular, we assume the objective of the the network manager. In particular, we assume that the objective of
job optimizer is to minimize the job completion time. the job optimizer is to minimize the job completion time.
In such a setting, the network-aware job optimizer (e.g., [CLARINET]) In such a setting, the network-aware job optimizer (e.g., [CLARINET])
takes a query and generates multiple query execution plans (QEP). It takes a query and generates multiple query execution plans (QEPs).
can encode the QEPs as Path Vector requests that are send to an ALTO It can encode the QEPs as Path Vector requests that are sent to an
server. The ALTO server obtains the routing information for the ALTO server. The ALTO server obtains the routing information for the
flows in a QEP and finds links, routers, or middleboxes (e.g., a flows in a QEP and finds links, routers, or middleboxes (e.g., a
stateful firewall) that can potentially become bottlenecks of the QEP stateful firewall) that can potentially become bottlenecks for the
(e.g., see [NOVA] and [G2] for mechanisms to identify bottleneck QEP (e.g., see [NOVA] and [G2] for mechanisms to identify bottleneck
links under different settings). The resource constraint information links under different settings). The resource constraint information
is encoded in a Path Vector response and returned to the ALTO client. is encoded in a Path Vector response and returned to the ALTO client.
With the network resource constraints, the job optimizer may choose With the network resource constraints, the job optimizer may choose
the QEP with the optimal job completion time to be executed. It must the QEP with the optimal job completion time to be executed. It must
be noted that the ALTO framework itself does not offer the capability be noted that the ALTO framework itself does not offer the capability
to control the traffic. However, certain network managers may offer to control the traffic. However, certain network managers may offer
ways to enforce resource guarantees, such as on-demand tunnels (e.g., ways to enforce resource guarantees, such as on-demand tunnels (e.g.,
[SWAN]), demand vector (e.g., [HUG], [UNICORN]), etc. The traffic [SWAN]), demand vectors (e.g., [HUG], [UNICORN]), etc. The traffic
control interfaces and mechanisms are out of the scope of this control interfaces and mechanisms are out of scope for this document.
document.
Data schema Queries Data schema Queries
| | | |
\ / \ /
+-------------+ +-----------------+ +-------------+ +-----------------+
| ALTO Client | <===============> | Job Optimizer | | ALTO Client | <===============> | Job Optimizer |
+-------------+ +-----------------+ +-------------+ +-----------------+
PV | ^ PV | PV | ^ PV |
Request | | Response | Request | | Response |
| | On-demand resource | | | On-demand resource |
(Data | | (Network allocation, demand | (Potential | | (Network allocation, demand |
Transfer | | Resource vector, etc. | Data | | Resource vectors, etc. |
Intents) | | Constraints) (Non-ALTO interfaces)| Transfers) | | Constraints) (Non-ALTO interfaces)|
v | v v | v
+-------------+ +-----------------+ +-------------+ +-----------------+
| ALTO Server | <===============> | Network Manager | | ALTO Server | <===============> | Network Manager |
+-------------+ +-----------------+ +-------------+ +-----------------+
/ | \ / | \
| | | | | |
WAN DC1 DC2 WAN DC1 DC2
Figure 3: Example Use Case for Data Analytics Figure 3: Example Use Case for Data Analytics
Another example is as illustrated in Figure 4. Consider a network Another example is illustrated in Figure 4. Consider a network
consisting of multiple sites and a non-blocking core network, i.e., consisting of multiple sites and a non-blocking core network, i.e.,
the links in the core network have sufficient bandwidth that they the links in the core network have sufficient bandwidth that they
will not become the bottleneck of the data transfers. will not become a bottleneck for the data transfers.
On-going transfers New transfer requests Ongoing transfers New transfer requests
\----\ | \----\ |
| | | |
v v v v
+-------------+ +---------------+ +-------------+ +---------------+
| ALTO Client | <===========> | Data Transfer | | ALTO Client | <===========> | Data Transfer |
+-------------+ | Scheduler | +-------------+ | Scheduler |
^ | ^ | PV request +---------------+ ^ | ^ | PV Request +---------------+
| | | \--------------\ | | | \--------------\
| | \--------------\ | | | \--------------\ |
| v PV response | v | v PV Response | v
+-------------+ +-------------+ +-------------+ +-------------+
| ALTO Server | | ALTO Server | | ALTO Server | | ALTO Server |
+-------------+ +-------------+ +-------------+ +-------------+
|| || || ||
+---------+ +---------+ +---------+ +---------+
| Network | | Network | | Network | | Network |
| Manager | | Manager | | Manager | | Manager |
+---------+ +---------+ +---------+ +---------+
. . . .
. _~_ __ . . . . _~_ __ . . .
. ( )( ) .___ . ( )( ) .___
~v~v~ /--( )------------( ) ~v~v~ /--( )------------( )
( )-----/ ( ) ( ) ( )-----/ ( ) ( )
~w~w~ ~^~^~^~ ~v~v~ ~w~w~ ~^~^~^~ ~v~v~
Site 1 Non-blocking Core Site 2 Site 1 Non-blocking Core Site 2
Figure 4: Example Use Case for Cross-site Bottleneck Discovery Figure 4: Example Use Case for Cross-Site Bottleneck Discovery
With the Path Vector extension, a site can reveal the bottlenecks
inside its own network with necessary information (such as link
capacities) to the ALTO client, instead of providing the full
topology and routing information, or no bottleneck information at
all. The bottleneck information can be used to analyze the impact of
adding/removing data transfer flows, e.g., using the framework
defined in [G2]. For example, assume that hosts "a", "b", and "c"
are in Site 1 and hosts "d", "e", and "f" are in Site 2, and there
are three flows in two sites: "a -> b", "c -> d", and "e -> f"
(Figure 5).
Site 1: Site 1:
[c] [c]
. .
........................................> [d] ........................................> [d]
+---+ 10 Gbps +---+ 10 Gbps +----+ 50 Gbps +---+ 10 Gbps +---+ 10 Gbps +----+ 50 Gbps
| A |---------| B |---------| GW |--------- Core | A |---------| B |---------| GW |--------- Core
+---+ +---+ +----+ +---+ +---+ +----+
................... ...................
skipping to change at page 14, line 31 skipping to change at line 588
+---+ 5 Gbps +---+ 10 Gbps +----+ 20 Gbps +---+ 5 Gbps +---+ 10 Gbps +----+ 20 Gbps
| X |--------| Y |---------| GW |--------- Core | X |--------| Y |---------| GW |--------- Core
+---+ +---+ +----+ +---+ +---+ +----+
.................... ....................
. . . .
. v . v
[e] [f] [e] [f]
Figure 5: Example: Three Flows in Two Sites Figure 5: Example: Three Flows in Two Sites
With the Path Vector extension, a site can reveal the bottlenecks For these flows, Site 1 returns:
inside its own network with necessary information (such as link
capacities) to the ALTO client, instead of providing the full
topology and routing information, or no bottleneck information at
all. The bottleneck information can be used to analyze the impact of
adding/removing data transfer flows, e.g., using the [G2] framework.
For example, assume hosts "a", "b", "c" are in site 1 and hosts "d",
"e", "f" are in site 2, and there are 3 flows in two sites: "a -> b",
"c -> d", "e -> f". For these flows, site 1 returns:
a: { b: [ane1] }, a: { b: [ane1] },
c: { d: [ane1, ane2, ane3] } c: { d: [ane1, ane2, ane3] }
ane1: bw = 10 Gbps (link: A->B) ane1: bw = 10 Gbps (link: A->B)
ane2: bw = 10 Gbps (link: B->GW) ane2: bw = 10 Gbps (link: B->GW)
ane3: bw = 50 Gbps (link: GW->Core) ane3: bw = 50 Gbps (link: GW->Core)
and site 2 returns: and Site 2 returns:
c: { d: [anei, aneii, aneiii] } c: { d: [anei, aneii, aneiii] }
e: { f: [aneiv] } e: { f: [aneiv] }
anei: bw = 5 Gbps (link Y->X) anei: bw = 5 Gbps (link Y->X)
aneii: bw = 10 Gbps (link GW->Y) aneii: bw = 10 Gbps (link GW->Y)
aneiii: bw = 20 Gbps (link Core->GW) aneiii: bw = 20 Gbps (link Core->GW)
aneiv: bw = 10 Gbps (link Y->GW) aneiv: bw = 10 Gbps (link Y->GW)
With the information, the data transfer scheduler can use algorithms With this information, the data transfer scheduler can use algorithms
such as the theory on bottleneck structure [G2] to predict the such as the theory on bottleneck structure [G2] to predict the
potential throughput of the flows. potential throughput of the flows.
4.2.2. Resource Exposure for CDN and Service Edge 4.2.2. Resource Exposure for CDNs and Service Edges
A growing trend in today's applications (2021) is to bring storage At the time of this writing, a growing trend in today's applications
and computation closer to the end users for better QoE, such as is to bring storage and computation closer to the end users for
Content Delivery Network (CDN), AR/VR, and cloud gaming, as reported better QoE, such as CDNs, augmented reality / virtual reality, and
in various documents (e.g., [SEREDGE] and [MOWIE]). Internet Service cloud gaming, as reported in various documents (e.g., [SEREDGE] and
Providers may deploy multiple layers of CDN caches, or more generally [MOWIE]). ISPs may deploy multiple layers of CDN caches or, more
service edges, with different latency and available resources generally, service edges, with different latencies and available
including number of CPU cores, memory, and storage. resources, including the number of CPU cores, memory, and storage.
For example, Figure 6 illustrates a typical edge-cloud scenario where For example, Figure 6 illustrates a typical edge-cloud scenario where
memory is measured in Gigabytes (G) and storage is measured in memory is measured in gigabytes (GB) and storage is measured in
Terabytes (T). The "on-premise" edge nodes are closest to the end terabytes (TB). The "on-premise" edge nodes are closest to the end
hosts and have the smallest latency, and the site-radio edge node and hosts and have the lowest latency, and the site-radio edge node and
access central office (CO) have larger latency but more available access central office (CO) have higher latencies but more available
resources. resources.
+-------------+ +----------------------+ +-------------+ +----------------------+
| ALTO Client | <==========> | Application Provider | | ALTO Client | <==========> | Application Provider |
+-------------+ +----------------------+ +-------------+ +----------------------+
PV | ^ PV | PV | ^ PV |
Request | | Response | Resource allocation, Request | | Response | Resource allocation,
| | | service establishment, | | | service establishment,
(End hosts | | (Edge nodes | etc. (End hosts | | (Edge nodes | etc.
and cloud | | and metrics) | and cloud | | and metrics) |
skipping to change at page 17, line 5 skipping to change at line 665
Site-radio /_\ / Site-radio /_\ /
Edge Node 2(/\_/\)-----/ Edge Node 2(/\_/\)-----/
/(_____)\ /(_____)\
___ / \ --- ___ / \ ---
b--|_| -/ \--|_|--c b--|_| -/ \--|_|--c
/---\ /---\ /---\ /---\
On premise On premise On premise On premise
Figure 6: Example Use Case for Service Edge Exposure Figure 6: Example Use Case for Service Edge Exposure
With the extension defined in this document, an ALTO server can
selectively reveal the CDNs and service edges that reside along the
paths between different end hosts and/or the cloud servers, together
with their properties (e.g., storage capabilities or Graphics
Processing Unit (GPU) capabilities) and available Service Level
Agreement (SLA) plans. See Figure 7 for an example where the query
is made for sources [a, b] and destinations [b, c, DC]. Here, each
ANE represents a service edge, and the properties include access
latency, available resources, etc. Note that the properties here are
only used for illustration purposes and are not part of this
extension.
a: { b: [ane1, ane2, ane3, ane4, ane5], a: { b: [ane1, ane2, ane3, ane4, ane5],
c: [ane1, ane2, ane3, ane4, ane6], c: [ane1, ane2, ane3, ane4, ane6],
DC: [ane1, ane2, ane3] } DC: [ane1, ane2, ane3] }
b: { c: [ane5, ane4, ane6], DC: [ane5, ane4, ane3] } b: { c: [ane5, ane4, ane6], DC: [ane5, ane4, ane3] }
ane1: latency=5ms cpu=2 memory=8G storage=10T ane1: latency = 5 ms cpu = 2 memory = 8 GB storage = 10 TB
(on premise, a) (On premise, a)
ane2: latency=20ms cpu=4 memory=8G storage=10T ane2: latency = 20 ms cpu = 4 memory = 8 GB storage = 10 TB
(Site-radio Edge Node 1) (Site-radio Edge Node 1)
ane3: latency=100ms cpu=8 memory=128G storage=100T ane3: latency = 100 ms cpu = 8 memory = 128 GB storage = 100 TB
(Access CO) (Access CO)
ane4: latency=20ms cpu=4 memory=8G storage=10T ane4: latency = 20 ms cpu = 4 memory = 8 GB storage = 10 TB
(Site-radio Edge Node 2) (Site-radio Edge Node 2)
ane5: latency=5ms cpu=2 memory=8G storage=10T ane5: latency = 5 ms cpu = 2 memory = 8 GB storage = 10 TB
(on premise, b) (On premise, b)
ane6: latency=5ms cpu=2 memory=8G storage=10T ane6: latency = 5 ms cpu = 2 memory = 8 GB storage = 10 TB
(on premise, c) (On premise, c)
Figure 7: Example Service Edge Query Results Figure 7: Example Service Edge Query Results
With the extension defined in this document, an ALTO server can
selectively reveal the CDNs and service edges that reside along the
paths between different end hosts and/or the cloud servers, together
with their properties such as capabilities (e.g., storage, GPU) and
available Service Level Agreement (SLA) plans. See Figure 7 for an
example where the query is made for sources [a, b] and destinations
[b, c, DC]. Here each ANE represents a service edge and the
properties include access latency, available resources, etc. Note
the properties here are only used for illustration purposes and are
not part of this extension.
With the service edge information, an ALTO client may better conduct With the service edge information, an ALTO client may better conduct
CDN request routing or offload functionalities from the user CDN request routing or offload functionalities from the user
equipment to the service edge, with considerations on customized equipment to the service edge, with considerations in place for
quality of experience. customized quality of experience.
5. Path Vector Extension: Overview 5. Path Vector Extension: Overview
This section provides a non-normative overview of the Path Vector This section provides a non-normative overview of the Path Vector
extension defined in this document. It is assumed that the readers extension defined in this document. It is assumed that readers are
are familiar with both the base protocol [RFC7285] and the Unified familiar with both the base protocol [RFC7285] and the entity
Property Map extension [I-D.ietf-alto-unified-props-new]. property map extension [RFC9240].
To satisfy the additional requirements listed in Section 4.1, this To satisfy the additional requirements listed in Section 4.1, this
extension: extension:
1. introduces the concept of Abstract Network Element (ANE) as the 1. introduces the concept of an ANE as the abstraction of components
abstraction of components in a network whose properties may have in a network whose properties may have an impact on end-to-end
an impact on the end-to-end performance of the traffic handled by performance of the traffic handled by those components,
those components,
2. extends the Cost Map and Endpoint Cost Service to convey the ANEs 2. extends the cost map and Endpoint Cost Service to convey the ANEs
traversed by the path of a <source, destination> pair as Path traversed by the path of a <source, destination> pair as Path
Vectors, and Vectors, and
3. uses the Unified Property Map to convey the association between 3. uses the entity property map to convey the association between
the ANEs and their properties. the ANEs and their properties.
Thus, an ALTO client can learn about the ANEs that are important to Thus, an ALTO client can learn about the ANEs that are important for
assess the QoE of different <source, destination> pairs by assessing the QoE of different <source, destination> pairs by
investigating the corresponding Path Vector value (AR1), identify investigating the corresponding Path Vector value (AR1) and can also
common ANEs if an ANE appears in the Path Vectors of multiple (1) identify common ANEs if an ANE appears in the Path Vectors of
<source, destination> pairs (AR2), and retrieve the properties of the multiple <source, destination> pairs (AR2) and (2) retrieve the
ANEs by searching the Unified Property Map (AR3). properties of the ANEs by searching the entity property map (AR3).
5.1. Abstract Network Element (ANE) 5.1. Abstract Network Element (ANE)
This extension introduces ANE as an indirect and network-agnostic way This extension introduces the ANE as an indirect and network-agnostic
to specify a component or an aggregation of components of a network way to specify a component or an aggregation of components of a
whose properties have an impact on the end-to-end performance for network whose properties have an impact on end-to-end performance for
application traffic between endpoints. application traffic between endpoints.
ANEs allow ALTO servers to focus on common properties of different ANEs allow ALTO servers to focus on common properties of different
types of network components. For example, the throughput of a flow types of network components. For example, the throughput of a flow
can be constrained by different components in a network: the capacity can be constrained by different components in a network: the capacity
of a physical link, the maximum throughput of a firewall, the of a physical link, the maximum throughput of a firewall, the
reserved bandwidth of an MPLS tunnel, etc. See the example below, reserved bandwidth of an MPLS tunnel, etc. In the example below,
assume the throughput of the firewall is 100 Mbps and the capacity assume that the throughput of the firewall is 100 Mbps and the
for link (A, B) is also 100 Mbps, they result in the same constraint capacity for link (A, B) is also 100 Mbps; they result in the same
on the total throughput of f1 and f2. Thus, they are identical when constraint on the total throughput of f1 and f2. Thus, they are
treated as an ANE. identical when treated as an ANE.
f1 | ^ f1 f1 | ^ f1
| | -----------------> | | ----------------->
+----------+ +---+ +---+ +----------+ +---+ +---+
| Firewall | | A |-----| B | | Firewall | | A |-----| B |
+----------+ +---+ +---+ +----------+ +---+ +---+
| | -----------------> | | ----------------->
v | f2 f2 v | f2 f2
When an ANE is defined by an ALTO server, it is assigned an When an ANE is defined by an ALTO server, it is assigned an
identifier by the ALTO server, i.e., a string of type ANEName as identifier by the ALTO server, i.e., a string of type ANEName as
specified in Section 6.1, and a set of associated properties. specified in Section 6.1, and a set of associated properties.
5.1.1. ANE Entity Domain 5.1.1. ANE Entity Domain
In this extension, the associations between ANE and the properties In this extension, the associations between ANEs and their properties
are conveyed in a Unified Property Map. Thus, ANEs must constitute an are conveyed in an entity property map. Thus, ANEs must constitute
entity domain (Section 5.1 of [I-D.ietf-alto-unified-props-new]), and an "entity domain" (Section 5.1 of [RFC9240]), and each ANE property
each ANE property must be an entity property (Section 5.2 of must be an entity property (Section 5.2 of [RFC9240]).
[I-D.ietf-alto-unified-props-new]).
Specifically, this document defines a new entity domain called "ane" Specifically, this document defines a new entity domain called "ane"
as specified in Section 6.2 and defines two initial properties for as specified in Section 6.2; Section 6.4 defines two initial property
the ANE entity domain. types for the ANE entity domain.
5.1.2. Ephemeral and Persistent ANEs 5.1.2. Ephemeral and Persistent ANEs
By design, ANEs are ephemeral and not to be used in further requests By design, ANEs are ephemeral and not to be used in further requests
to other ALTO resources. More precisely, the corresponding ANE names to other ALTO resources. More precisely, the corresponding ANE names
are no longer valid beyond the scope of a Path Vector response or the are no longer valid beyond the scope of a Path Vector response or the
incremental update stream for a Path Vector request. Compared with incremental update stream for a Path Vector request. Compared with
globally unique ANE names, ephemeral ANE has several benefits globally unique ANE names, ephemeral ANEs have several benefits,
including better privacy of the ISP's internal structure and more including better privacy for the ISP's internal structure and more
flexible ANE computation. flexible ANE computation.
For example, an ALTO server may define an ANE for each aggregated For example, an ALTO server may define an ANE for each aggregated
bottleneck link between the sources and destinations specified in the bottleneck link between the sources and destinations specified in the
request. For requests with different sources and destinations, the request. For requests with different sources and destinations, the
bottlenecks may be different but can safely reuse the same ANE names. bottlenecks may be different but can safely reuse the same ANE names.
The client can still adjust its traffic based on the information but The client can still adjust its traffic based on the information, but
is difficult to infer the underlying topology with multiple queries. it is difficult to infer the underlying topology with multiple
queries.
However, sometimes an ISP may intend to selectively reveal some However, sometimes an ISP may intend to selectively reveal some
"persistent" network components which, opposite to being ephemeral, "persistent" network components that, as opposed to being ephemeral,
have a longer life cycle. For example, an ALTO server may define an have a longer life cycle. For example, an ALTO server may define an
ANE for each service edge cluster. Once a client chooses to use a ANE for each service edge cluster. Once a client chooses to use a
service edge, e.g., by deploying some user-defined functions, it may service edge, e.g., by deploying some user-defined functions, it may
want to stick to the service edge to avoid the complexity of state want to stick to the service edge to avoid the complexity of state
transition or synchronization, and continuously query the properties transition or synchronization, and continuously query the properties
of the edge cluster. of the edge cluster.
This document provides a mechanism to expose such network components This document provides a mechanism to expose such network components
as persistent ANEs. A persistent ANE has a persistent ID that is as persistent ANEs. A persistent ANE has a persistent ID that is
registered in a Property Map, together with their properties. See registered in a property map, together with its properties. See
Section 6.2.4 and Section 6.4.2 for more detailed instructions on how Sections 6.2.4 and 6.4.2 for more detailed instructions on how to
to identify ephemeral ANEs and persistent ANEs. identify ephemeral ANEs and persistent ANEs.
5.1.3. Property Filtering 5.1.3. Property Filtering
Resource-constrained ALTO clients (see Section 4.1.2 of [RFC7285]) Resource-constrained ALTO clients (see Section 4.1.2 of [RFC7285])
may benefit from the filtering of Path Vector query results at the may benefit from the filtering of Path Vector query results at the
ALTO server, as an ALTO client may only require a subset of the ALTO server, as an ALTO client may only require a subset of the
available properties. available properties.
Specifically, the available properties for a given resource are Specifically, the available properties for a given resource are
announced in the Information Resource Directory as a new capability announced in the Information Resource Directory (IRD) as a new
called "ane-property-names". The properties selected by a client as filtering capability called "ane-property-names". The properties
being of interest are specified in the subsequent Path Vector queries selected by a client as being of interest are specified in the
using the filter called 'ane-property-names'. The response includes subsequent Path Vector queries using the "ane-property-names" filter.
and only includes the selected properties for the ANEs in the The response only includes the selected properties for the ANEs.
response.
The "ane-property-names" capability for Cost Map and for Endpoint The "ane-property-names" capability for the cost map and the Endpoint
Cost Service is specified in Section 7.2.4 and Section 7.3.4 Cost Service is specified in Sections 7.2.4 and 7.3.4, respectively.
respectively. The "ane-property-names" filter for Cost Map and The "ane-property-names" filter for the cost map and the Endpoint
Endpoint Cost Service is specified in Section 7.2.3 and Section 7.3.3 Cost Service is specified in Sections 7.2.3 and 7.3.3 accordingly.
accordingly.
5.2. Path Vector Cost Type 5.2. Path Vector Cost Type
For an ALTO client to correctly interpret the Path Vector, this For an ALTO client to correctly interpret the Path Vector, this
extension specifies a new cost type called the Path Vector cost type. extension specifies a new cost type called the "Path Vector cost
type".
The Path Vector cost type must convey both the interpretation and The Path Vector cost type must convey both the interpretation and
semantics in the "cost-mode" and "cost-metric" respectively. semantics in the "cost-mode" and "cost-metric" parameters,
Unfortunately, a single "cost-mode" value cannot fully specify the respectively. Unfortunately, a single "cost-mode" value cannot fully
interpretation of a Path Vector, which is a compound data type. For specify the interpretation of a Path Vector, which is a compound data
example, in programming languages such as C++ where there existed a type. For example, in programming languages such as C++, if there
JSON array type named JSONArray, a Path Vector will have the type of existed a JSON array type named JSONArray, a Path Vector would have
JSONArray<ANEName>. the type of JSONArray<ANEName>.
Instead of extending the "type system" of ALTO, this document takes a Instead of extending the "type system" of ALTO, this document takes a
simple and backward compatible approach. Specifically, the "cost- simple and backward-compatible approach. Specifically, the "cost-
mode" of the Path Vector cost type is "array", which indicates the mode" of the Path Vector cost type is "array", which indicates that
value is a JSON array. Then, an ALTO client must check the value of the value is a JSON array. Then, an ALTO client must check the value
the "cost-metric". If the value is "ane-path", it means that the of the "cost-metric" parameter. If the value is "ane-path", it means
JSON array should be further interpreted as a path of ANENames. that the JSON array should be further interpreted as a path of
ANENames.
The Path Vector cost type is specified in Section 6.5. The Path Vector cost type is specified in Section 6.5.
5.3. Multipart Path Vector Response 5.3. Multipart Path Vector Response
For a basic ALTO information resource, a response contains only one For a basic ALTO information resource, a response contains only one
type of ALTO resources, e.g., Network Map, Cost Map, or Property Map. type of ALTO resource, e.g., network map, cost map, or property
Thus, only one round of communication is required: An ALTO client map. Thus, only one round of communication is required: an ALTO
sends a request to an ALTO server, and the ALTO server returns a client sends a request to an ALTO server, and the ALTO server returns
response, as shown in Figure 8. a response, as shown in Figure 8.
ALTO client ALTO server ALTO client ALTO server
|-------------- Request ---------------->| |-------------- Request ---------------->|
|<------------- Response ----------------| |<------------- Response ----------------|
Figure 8: A Typical ALTO Request and Response Figure 8: A Typical ALTO Request and Response
The extension defined in this document, on the other hand, involves The extension defined in this document, on the other hand, involves
two types of information resources: Path Vectors conveyed in an two types of information resources: Path Vectors conveyed in an
InfoResourceCostMap (defined in Section 11.2.3.6 of [RFC7285]) or an InfoResourceCostMap data component (defined in Section 11.2.3.6 of
InfoResourceEndpointCostMap (defined in Section 11.5.1.6 of [RFC7285]) or an InfoResourceEndpointCostMap data component (defined
[RFC7285]), and ANE properties conveyed in an InfoResourceProperties in Section 11.5.1.6 of [RFC7285]), and ANE properties conveyed in an
(defined in Section 7.6 of [I-D.ietf-alto-unified-props-new]). InfoResourceProperties data component (defined in Section 7.6 of
[RFC9240]).
Instead of two consecutive message exchanges, the extension defined Instead of two consecutive message exchanges, the extension defined
in this document enforces one round of communication. Specifically, in this document enforces one round of communication. Specifically,
the ALTO client must include the source and destination pairs and the the ALTO client must include the source and destination pairs and the
requested ANE properties in a single request, and the ALTO server requested ANE properties in a single request, and the ALTO server
must return a single response containing both the Path Vectors and must return a single response containing both the Path Vectors and
properties associated with the ANEs in the Path Vectors, as shown in properties associated with the ANEs in the Path Vectors, as shown in
Figure 9. Since the two parts are bundled together in one response Figure 9. Since the two parts are bundled together in one response
message, their orders are interchangeable. See Section 7.2.6 and message, their orders are interchangeable. See Sections 7.2.6 and
Section 7.3.6 for details. 7.3.6 for details.
ALTO client ALTO server ALTO client ALTO server
|------------- PV Request -------------->| |------------- PV Request -------------->|
|<----- PV Response (Cost Map Part) -----| |<----- PV Response (Cost Map Part) -----|
|<--- PV Response (Property Map Part) ---| |<--- PV Response (Property Map Part) ---|
Figure 9: The Path Vector Extension Request and Response Figure 9: The Path Vector Extension Request and Response
This design is based on the following considerations: This design is based on the following considerations:
1. ANEs may be constructed on demand, and potentially based on the 1. ANEs may be constructed on demand and, potentially, based on the
requested properties (See Section 5.1 for more details). If requested properties (see Section 5.1 for more details). If
sources and destinations are not in the same request as the sources and destinations are not in the same request as the
properties, an ALTO server either cannot construct ANEs on- properties, an ALTO server either cannot construct ANEs on demand
demand, or must wait until both requests are received. or must wait until both requests are received.
2. As ANEs may be constructed on demand, mappings of each ANE to its 2. As ANEs may be constructed on demand, mappings of each ANE to its
underlying network devices and resources can be specific to the underlying network devices and resources can be specific to the
request. In order to respond to the Property Map request request. In order to respond to the property map request
correctly, an ALTO server must store the mapping of each Path correctly, an ALTO server must store the mapping of each Path
Vector request until the client fully retrieves the property Vector request until the client fully retrieves the property
information. The "stateful" behavior may substantially harm the information. This "stateful" behavior may substantially harm
server scalability and potentially lead to Denial-of-Service server scalability and potentially lead to denial-of-service
attacks. attacks.
One approach to realize the one-round communication is to define a One approach for realizing the one-round communication is to define a
new media type to contain both objects, but this violates modular new media type to contain both objects, but this violates modular
design. This document follows the standard-conforming usage of design. This document follows the standard-conforming usage of the
"multipart/related" media type defined in [RFC2387] to elegantly "multipart/related" media type as defined in [RFC2387] to elegantly
combine the objects. Path Vectors are encoded in an combine the objects. Path Vectors are encoded in an
InfoResourceCostMap or an InfoResourceEndpointCostMap, and the InfoResourceCostMap data component or InfoResourceEndpointCostMap
Property Map is encoded in an InfoResourceProperties. They are data component, and the property map is encoded in an
encapsulated as parts of a multipart message. The modular InfoResourceProperties data component. They are encapsulated as
composition allows ALTO servers and clients to reuse the data models parts of a multipart message. This modular composition allows ALTO
of the existing information resources. Specifically, this document servers and clients to reuse the data models of the existing
addresses the following practical issues using "multipart/related". information resources. Specifically, this document addresses the
following practical issues using "multipart/related".
5.3.1. Identifying the Media Type of the Root Object 5.3.1. Identifying the Media Type of the Object Root
ALTO uses media type to indicate the type of an entry in the ALTO uses a media type to indicate the type of an entry in the IRD
Information Resource Directory (IRD) (e.g., "application/alto- (e.g., "application/alto-costmap+json" for the cost map and
costmap+json" for Cost Map and "application/alto-endpointcost+json" "application/alto-endpointcost+json" for the Endpoint Cost Service).
for Endpoint Cost Service). Simply putting "multipart/related" as Simply using "multipart/related" as the media type, however, makes it
the media type, however, makes it impossible for an ALTO client to impossible for an ALTO client to identify the type of service
identify the type of service provided by related entries. provided by related entries.
To address this issue, this document uses the "type" parameter to To address this issue, this document uses the "type" parameter to
indicate the root object of a multipart/related message. For a Cost indicate the object root of a multipart/related message. For a cost
Map resource, the "media-type" field in the IRD entry is "multipart/ map resource, the "media-type" field in the IRD entry is "multipart/
related" with the parameter "type=application/alto-costmap+json"; for related" with the parameter "type=application/alto-costmap+json"; for
an Endpoint Cost Service, the parameter is "type=application/alto- an Endpoint Cost Service, the parameter is "type=application/alto-
endpointcost+json". endpointcost+json".
5.3.2. References to Part Messages 5.3.2. References to Part Messages
As the response of a Path Vector resource is a multipart message with As the response of a Path Vector resource is a multipart message with
two different parts, it is important that each part can be uniquely two different parts, it is important that each part can be uniquely
identified. Following the designs of [RFC8895], this extension identified. Following the design provided in [RFC8895], this
requires that an ALTO server assigns a unique identifier to each part extension requires that an ALTO server assign a unique identifier to
of the multipart response message. This identifier, referred to as a each part of the multipart response message. This identifier,
Part Resource ID (See Section 6.6 for details), is present in the referred to as a Part Resource ID (see Section 6.6 for details), is
part message's "Content-ID" header. By concatenating the Part present in the part message's "Content-ID" header field. By
Resource ID to the identifier of the Path Vector request, an ALTO concatenating the Part Resource ID to the identifier of the Path
server/client can uniquely identify the Path Vector Part or the Vector request, an ALTO server/client can uniquely identify the Path
Property Map part. Vector part or the property map part.
6. Specification: Basic Data Types 6. Specification: Basic Data Types
6.1. ANE Name 6.1. ANE Name
An ANE Name is encoded as a JSON string with the same format as that An ANE name is encoded as a JSON string with the same format as that
of the type PIDName (Section 10.1 of [RFC7285]). of the type PIDName (Section 10.1 of [RFC7285]).
The type ANEName is used in this document to indicate a string of The type ANEName is used in this document to indicate a string of
this format. this format.
6.2. ANE Entity Domain 6.2. ANE Entity Domain
The ANE entity domain associates property values with the Abstract The ANE entity domain associates property values with the ANEs in a
Network Elements in a Property Map. Accordingly, the ANE entity property map. Accordingly, the ANE entity domain always depends on a
domain always depends on a Property Map. property map.
It must be noted that the term "domain" here does not refer to a It must be noted that the term "domain" here does not refer to a
network domain. Rather, it is inherited from the "entity domain" network domain. Rather, it is inherited from the entity domain as
defined in Sec 3.2 in [I-D.ietf-alto-unified-props-new] that defined in Section 3.2 of [RFC9240]; the entity domain represents the
represents the set of valid entities defined by an ALTO information set of valid entities defined by an ALTO information resource (called
resource (called the defining information resource). the "defining information resource").
6.2.1. Entity Domain Type 6.2.1. Entity Domain Type
The Entity Domain Type is "ane". The entity domain type is "ane".
6.2.2. Domain-Specific Entity Identifier 6.2.2. Domain-Specific Entity Identifier
The entity identifiers are the ANE Names in the associated Property The entity identifiers are the ANE names in the associated property
Map. map.
6.2.3. Hierarchy and Inheritance 6.2.3. Hierarchy and Inheritance
There is no hierarchy or inheritance for properties associated with There is no hierarchy or inheritance for properties associated with
ANEs. ANEs.
6.2.4. Media Type of Defining Resource 6.2.4. Media Type of Defining Resource
The defining resource for entity domain type "ane" MUST be a Property The defining resource for entity domain type "ane" MUST be a property
Map, i.e., the media type of defining resources is: map, i.e., the media type of defining resources is:
application/alto-propmap+json application/alto-propmap+json
Specifically, for ephemeral ANEs that appear in a Path Vector Specifically, for ephemeral ANEs that appear in a Path Vector
response, their entity domain names MUST be exactly ".ane" and the response, their entity domain names MUST be exactly ".ane", and the
defining resource of these ANEs is the Property Map part of the defining resource of these ANEs is the property map part of the
multipart response. Meanwhile, for any persistent ANE whose defining multipart response. Meanwhile, for any persistent ANE whose defining
resource is a Property Map resource, its entity domain name MUST have resource is a property map resource, its entity domain name MUST have
the format of "PROPMAP.ane" where PROPMAP is the resource ID of the the format of "PROPMAP.ane", where PROPMAP is the resource ID of the
defining resource. Persistent entities are "persistent" because defining resource. Persistent entities are "persistent" because
standalone queries can be made by an ALTO client to their defining standalone queries can be made by an ALTO client to their defining
resource(s) when the connection to the Path Vector service is closed. resource(s) when the connection to the Path Vector service is closed.
For example, the defining resource of an ephemeral ANE whose entity For example, the defining resource of an ephemeral ANE whose entity
identifier is ".ane:NET1" is the Property Map part that contains this identifier is ".ane:NET1" is the property map part that contains this
identifier. The defining resource of a persistent ANE whose entity identifier. The defining resource of a persistent ANE whose entity
identifier is "dc-props.ane:DC1" is the Property Map with the identifier is "dc-props.ane:DC1" is the property map with the
resource ID "dc-props". resource ID "dc-props".
6.3. ANE Property Name 6.3. ANE Property Name
An ANE Property Name is encoded as a JSON string with the same format An ANE property name is encoded as a JSON string with the same format
as that of Entity Property Name (Section 5.2.2 of as that of an entity property name (Section 5.2.2 of [RFC9240]).
[I-D.ietf-alto-unified-props-new]).
6.4. Initial ANE Property Types 6.4. Initial ANE Property Types
Two initial ANE property types are specified, "max-reservable- Two initial ANE property types are specified: "max-reservable-
bandwidth" and "persistent-entity-id". bandwidth" and "persistent-entity-id".
Note that these property types do not depend on any information Note that these property types do not depend on any information
resource. As such, the EntityPropertyName MUST only have the resources. As such, the "EntityPropertyName" parameter MUST only
EntityPropertyType part. have the EntityPropertyType part.
6.4.1. Maximum Reservable Bandwidth 6.4.1. Maximum Reservable Bandwidth
The maximum reservable bandwidth property ("max-reservable- The maximum reservable bandwidth property ("max-reservable-
bandwidth") stands for the maximum bandwidth that can be reserved for bandwidth") stands for the maximum bandwidth that can be reserved for
all the traffic that traverses an ANE. The value MUST be encoded as all the traffic that traverses an ANE. The value MUST be encoded as
a non-negative numerical cost value as defined in Section 6.1.2.1 of a non-negative numerical cost value as defined in Section 6.1.2.1 of
[RFC7285] and the unit is bit per second (bps). If this property is [RFC7285], and the unit is bits per second (bps). If this property
requested by the ALTO client but not present for an ANE in the server is requested by the ALTO client but is not present for an ANE in the
response, it MUST be interpreted as that the property is not defined server response, it MUST be interpreted as meaning that the property
for the ANE. is not defined for the ANE.
This property can be offered in a setting where the ALTO server is This property can be offered in a setting where the ALTO server is
part of a network system that provides on-demand resource allocation part of a network system that provides on-demand resource allocation
and the ALTO client is part of a user application. One existing and the ALTO client is part of a user application. One existing
example is [NOVA]: the ALTO server is part of an SDN controller and example is [NOVA]: the ALTO server is part of a Software-Defined
exposes a list of traversed network elements and associated link Networking (SDN) controller and exposes a list of traversed network
bandwidth to the client. The encoding in [NOVA] differs from the elements and associated link bandwidth to the client. The encoding
Path Vector response defined in this document that the Path Vector in [NOVA] differs from the Path Vector response defined in this
part and Property Map part are put in the same JSON object. document in that the Path Vector part and property map part are
placed in the same JSON object.
In such a framework, the ALTO server exposes resource (e.g., In such a framework, the ALTO server exposes resource availability
reservable bandwidth) availability information to the ALTO client. information (e.g., reservable bandwidth) to the ALTO client. How the
How the client makes resource requests based on the information and client makes resource requests based on the information, and how the
how the resource allocation is achieved respectively depend on resource allocation is achieved, respectively, depend on interfaces
interfaces between the management system and the users or a higher- between the management system and the users or a higher-layer
layer protocol (e.g., SDN network intents or MPLS tunnels), which are protocol (e.g., SDN network intents [INTENT-BASED-NETWORKING] or MPLS
out of the scope of this document. tunnels), which are out of scope for this document.
6.4.2. Persistent Entity ID 6.4.2. Persistent Entity ID
The persistent entity ID property is the entity identifier of the This document enables the discovery of a persistent ANE by exposing
persistent ANE which an ephemeral ANE presents (See Section 5.1.2 for its entity identifier as the persistent entity ID property of an
details). The value of this property is encoded with the format ephemeral ANE in the path vector response. The value of this
EntityID defined in Section 5.1.3 of property is encoded with the EntityID format defined in Section 5.1.3
[I-D.ietf-alto-unified-props-new]. of [RFC9240].
In this format, the entity ID combines: In this format, the entity ID combines:
* a defining information resource for the ANE on which a * a defining information resource for the ANE on which a
"persistent-entity-id" is queried, which is the Property Map "persistent-entity-id" is queried, which is the property map
resource defining the ANE as a persistent entity, together with resource defining the ANE as a persistent entity, together with
the properties; the properties.
* the persistent name of the ANE in that Property Map. * the persistent name of the ANE in that property map.
With this format, the client has all the needed information for With this format, the client has all the needed information for
further standalone query properties on the persistent ANE. further standalone query properties on the persistent ANE.
6.4.3. Examples 6.4.3. Examples
To illustrate the use of "max-reservable-bandwidth", consider the To illustrate the use of "max-reservable-bandwidth", consider the
following network with 5 nodes. Assume the client wants to query the following network with five nodes. Assume that the client wants to
maximum reservable bandwidth from H1 to H2. An ALTO server may split query the maximum reservable bandwidth from H1 to H2. An ALTO server
the network into two ANEs: "ane1" that represents the subnetwork with may split the network into two ANEs: "ane1", which represents the
routers A, B, and C, and "ane2" that represents the subnetwork with subnetwork with routers A, B, and C; and "ane2", which represents the
routers B, D and E. The maximum reservable bandwidth for "ane1" is subnetwork with routers B, D, and E. The maximum reservable
15 Mbps (using path A->C->B) and the maximum reservable bandwidth for bandwidth for "ane1" is 15 Mbps (using path A->C->B), and the maximum
"ane2" is 20 Mbps (using path B->D->E). reservable bandwidth for "ane2" is 20 Mbps (using path B->D->E).
20 Mbps 20 Mbps 20 Mbps 20 Mbps
10 Mbps +---+ +---+ +---+ 10 Mbps +---+ +---+ +---+
/----| B |---| D |----| E |---- H2 /----| B |---| D |----| E |---- H2
+---+/ +---+ +---+ +---+ +---+/ +---+ +---+ +---+
H1 ----| A | 15 Mbps| H1 ----| A | 15 Mbps|
+---+\ +---+ +---+\ +---+
\----| C | \----| C |
15 Mbps +---+ 15 Mbps +---+
To illustrate the use of "persistent-entity-id", consider the To illustrate the use of "persistent-entity-id", consider the
scenario in Figure 6. As the life cycle of service edges are scenario in Figure 6. As the life cycles of service edges are
typically long, they may contain information that is not specific to typically long, the service edges may contain information that is not
the query. Such information can be stored in an individual unified specific to the query. Such information can be stored in an
property map and later be accessed by an ALTO client. individual entity property map and can later be accessed by an ALTO
client.
For example, "ane1" in Figure 7 represents the on-premise service For example, "ane1" in Figure 7 represents the on-premise service
edge closest to host a. Assume the properties of the service edges edge closest to host "a". Assume that the properties of the service
are provided in a unified property map called "se-props" and the ID edges are provided in an entity property map called "se-props" and
of the on-premise service edge is "9a0b55f7-7442-4d56-8a2c- the ID of the on-premise service edge is "9a0b55f7-7442-4d56-8a2c-
b4cc6a8e3aa1", the "persistent-entity-id" of "ane1" will be "se- b4cc6a8e3aa1"; the "persistent-entity-id" setting for "ane1" will be
props.ane:9a0b55f7-7442-4d56-8a2c-b4cc6a8e3aa1". With this "se-props.ane:9a0b55f7-7442-4d56-8a2c-b4cc6a8e3aa1". With this
persistent entity ID, an ALTO client may send queries to the "se- persistent entity ID, an ALTO client may send queries to the "se-
props" resource with the entity ID ".ane:9a0b55f7-7442-4d56-8a2c- props" resource with the entity ID ".ane:9a0b55f7-7442-4d56-8a2c-
b4cc6a8e3aa1". b4cc6a8e3aa1".
6.5. Path Vector Cost Type 6.5. Path Vector Cost Type
This document defines a new cost type, which is referred to as the This document defines a new cost type, which is referred to as the
Path Vector cost type. An ALTO server MUST offer this cost type if Path Vector cost type. An ALTO server MUST offer this cost type if
it supports the extension defined in this document. it supports the extension defined in this document.
6.5.1. Cost Metric: ane-path 6.5.1. Cost Metric: "ane-path"
The cost metric "ane-path" indicates the value of such a cost type The cost metric "ane-path" indicates that the value of such a cost
conveys an array of ANE names, where each ANE name uniquely type conveys an array of ANE names, where each ANE name uniquely
represents an ANE traversed by traffic from a source to a represents an ANE traversed by traffic from a source to a
destination. destination.
An ALTO client MUST interpret the Path Vector as if the traffic An ALTO client MUST interpret the Path Vector as if the traffic
between a source and a destination logically traverses the ANEs in between a source and a destination logically traverses the ANEs in
the same order as they appear in the Path Vector. the same order as they appear in the Path Vector.
When the Path Vector procedures defined in this document are in use, When the Path Vector procedures defined in this document are in use,
an ALTO server using the "ane-path" cost metric and the "array" cost an ALTO server using the "ane-path" cost metric and the "array" cost
mode (see Section 6.5.2) MUST return as the cost value a JSON array mode (see Section 6.5.2) MUST return as the cost value a JSON array
of ANEName and the client MUST also check that each element contained of data type ANEName, and the client MUST also check that each
in the array is an ANEName (Section 6.1). Otherwise, the client MUST element contained in the array is an ANEName (Section 6.1).
discard the response and SHOULD follow the instructions in Otherwise, the client MUST discard the response and SHOULD follow the
Section 8.3.4.3 of [RFC7285] to handle the error. guidance in Section 8.3.4.3 of [RFC7285] to handle the error.
6.5.2. Cost Mode: array 6.5.2. Cost Mode: "array"
The cost mode "array" indicates that every cost value in the response The cost mode "array" indicates that every cost value in the response
body of a (Filtered) Cost Map or an Endpoint Cost Service MUST be body of a (filtered) cost map or an Endpoint Cost Service MUST be
interpreted as a JSON array object. While this cost mode can be interpreted as a JSON array object. While this cost mode can be
applied to all cost metrics, additional specifications will be needed applied to all cost metrics, additional specifications will be needed
to clarify the semantics of the array cost mode when combined with to clarify the semantics of the "array" cost mode when combined with
cost metrics other than 'ane-path'. cost metrics other than "ane-path".
6.6. Part Resource ID and Part Content ID 6.6. Part Resource ID and Part Content ID
A Part Resource ID is encoded as a JSON string with the same format A Part Resource ID is encoded as a JSON string with the same format
as that of the type ResourceID (Section 10.2 of [RFC7285]). as that of the type ResourceID (Section 10.2 of [RFC7285]).
Even though the client-id assigned to a Path Vector request and the Even though the "client-id" assigned to a Path Vector request and the
Part Resource ID MAY contain up to 64 characters by their own Part Resource ID MAY contain up to 64 characters by their own
definition, their concatenation (see Section 5.3.2) MUST also conform definition, their concatenation (see Section 5.3.2) MUST also conform
to the same length constraint. The same requirement applies to the to the same length constraint. The same requirement applies to the
resource ID of the Path Vector resource, too. Thus, it is resource ID of the Path Vector resource, too. Thus, it is
RECOMMENDED to limit the length of resource ID and client ID related RECOMMENDED to limit the length of the resource ID and client ID
to a Path Vector resource to 31 characters. related to a Path Vector resource to 31 characters.
A Part Content ID conforms to the format of msg-id as specified in A Part Content ID conforms to the format of "msg-id" as specified in
[RFC2387] and [RFC5322]. Specifically, it has the following format: [RFC2387] and [RFC5322]. Specifically, it has the following format:
"<" PART-RESOURCE-ID "@" DOMAIN-NAME ">" "<" PART-RESOURCE-ID "@" DOMAIN-NAME ">"
PART-RESOURCE-ID: PART-RESOURCE-ID has the same format as the Part PART-RESOURCE-ID: PART-RESOURCE-ID has the same format as the Part
Resource ID. It is used to identify whether a part message is a Resource ID. It is used to identify whether a part message is a
Path Vector or a Property Map. Path Vector or a property map.
DOMAIN-NAME: DOMAIN-NAME has the same format as dot-atom-text DOMAIN-NAME: DOMAIN-NAME has the same format as "dot-atom-text" as
specified in Section 3.2.3 of [RFC5322]. It must be the domain specified in Section 3.2.3 of [RFC5322]. It must be the domain
name of the ALTO server. name of the ALTO server.
7. Specification: Service Extensions 7. Specification: Service Extensions
7.1. Notations 7.1. Notation
This document uses the same syntax and notations as introduced in This document uses the same syntax and notation as those introduced
Section 8.2 of RFC 7285 [RFC7285] to specify the extensions to in Section 8.2 of [RFC7285] to specify the extensions to existing
existing ALTO resources and services. ALTO resources and services.
7.2. Multipart Filtered Cost Map for Path Vector 7.2. Multipart Filtered Cost Map for Path Vector
This document introduces a new ALTO resource called multipart This document introduces a new ALTO resource called the "multipart
Filtered Cost Map resource, which allows an ALTO server to provide filtered cost map resource", which allows an ALTO server to provide
other ALTO resources associated with the Cost Map resource in the other ALTO resources associated with the cost map resource in the
same response. same response.
7.2.1. Media Type 7.2.1. Media Type
The media type of the multipart Filtered Cost Map resource is The media type of the multipart filtered cost map resource is
"multipart/related" and the required "type" parameter MUST have a "multipart/related", and the required "type" parameter MUST have a
value of "application/alto-costmap+json". value of "application/alto-costmap+json".
7.2.2. HTTP Method 7.2.2. HTTP Method
The multipart Filtered Cost Map is requested using the HTTP POST The multipart filtered cost map is requested using the HTTP POST
method. method.
7.2.3. Accept Input Parameters 7.2.3. Accept Input Parameters
The input parameters of the multipart Filtered Cost Map are supplied The input parameters of the multipart filtered cost map are supplied
in the body of an HTTP POST request. This document extends the input in the body of an HTTP POST request. This document extends the input
parameters to a Filtered Cost Map, which is defined as a JSON object parameters to a filtered cost map, which is defined as a JSON object
of type ReqFilteredCostMap in Section 4.1.2 of RFC 8189 [RFC8189], of type ReqFilteredCostMap in Section 4.1.2 of [RFC8189], with a data
with a data format indicated by the media type "application/alto- format indicated by the media type "application/alto-
costmapfilter+json", which is a JSON object of type costmapfilter+json", which is a JSON object of type
PVReqFilteredCostMap: PVReqFilteredCostMap:
object { object {
[EntityPropertyName ane-property-names<0..*>;] [EntityPropertyName ane-property-names<0..*>;]
} PVReqFilteredCostMap : ReqFilteredCostMap; } PVReqFilteredCostMap : ReqFilteredCostMap;
with fields: with field:
ane-property-names: A list of selected ANE properties to be included ane-property-names: This field provides a list of selected ANE
in the response. Each property in this list MUST match one of the properties to be included in the response. Each property in this
supported ANE properties indicated in the resource's "ane- list MUST match one of the supported ANE properties indicated in
property-names" capability (Section 7.2.4). If the field is not the resource's "ane-property-names" capability (Section 7.2.4).
present, it MUST be interpreted as an empty list. If the field is not present, it MUST be interpreted as an empty
list.
Example: Consider the network in Figure 1. If an ALTO client wants Example: Consider the network in Figure 1. If an ALTO client wants
to query the "max-reservable-bandwidth" between PID1 and PID2, it can to query the "max-reservable-bandwidth" setting between PID1 and
submit the following request. PID2, it can submit the following request.
POST /costmap/pv HTTP/1.1 POST /costmap/pv HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: multipart/related;type=application/alto-costmap+json, Accept: multipart/related;type=application/alto-costmap+json,
application/alto-error+json application/alto-error+json
Content-Length: 201 Content-Length: 212
Content-Type: application/alto-costmapfilter+json Content-Type: application/alto-costmapfilter+json
{ {
"cost-type": { "cost-type": {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, },
"pids": { "pids": {
"srcs": [ "PID1" ], "srcs": [ "PID1" ],
"dsts": [ "PID2" ] "dsts": [ "PID2" ]
}, },
"ane-property-names": [ "max-reservable-bandwidth" ] "ane-property-names": [ "max-reservable-bandwidth" ]
} }
7.2.4. Capabilities 7.2.4. Capabilities
The multipart Filtered Cost Map resource extends the capabilities The multipart filtered cost map resource extends the capabilities
defined in Section 4.1.1 of [RFC8189]. The capabilities are defined defined in Section 4.1.1 of [RFC8189]. The capabilities are defined
by a JSON object of type PVFilteredCostMapCapabilities: by a JSON object of type PVFilteredCostMapCapabilities:
object { object {
[EntityPropertyName ane-property-names<0..*>;] [EntityPropertyName ane-property-names<0..*>;]
} PVFilteredCostMapCapabilities : FilteredCostMapCapabilities; } PVFilteredCostMapCapabilities : FilteredCostMapCapabilities;
with fields: with field:
ane-property-names: Defines a list of ANE properties that can be ane-property-names: This field provides a list of ANE properties
returned. If the field is not present, it MUST be interpreted as that can be returned. If the field is not present, it MUST be
an empty list, indicating the ALTO server cannot provide any ANE interpreted as an empty list, indicating that the ALTO server
property. cannot provide any ANE properties.
This extension also introduces additional restrictions for the This extension also introduces additional restrictions for the
following fields: following fields:
cost-type-names: The "cost-type-names" field MUST include the Path cost-type-names: The "cost-type-names" field MUST include the Path
Vector cost type, unless explicitly documented by a future Vector cost type, unless explicitly documented by a future
extension. This also implies that the Path Vector cost type MUST extension. This also implies that the Path Vector cost type MUST
be defined in the "cost-types" of the Information Resource be defined in the "cost-types" of the IRD's "meta" field.
Directory's "meta" field.
cost-constraints: If the "cost-type-names" field includes the Path cost-constraints: If the "cost-type-names" field includes the Path
Vector cost type, "cost-constraints" field MUST be "false" or not Vector cost type, the "cost-constraints" field MUST be either
present unless specifically instructed by a future document. "false" or not present, unless specifically instructed by a future
document.
testable-cost-type-names (Section 4.1.1 of [RFC8189]): If the "cost- testable-cost-type-names (Section 4.1.1 of [RFC8189]): If the "cost-
type-names" field includes the Path Vector cost type and the type-names" field includes the Path Vector cost type and the
"testable-cost-type-names" field is present, the Path Vector cost "testable-cost-type-names" field is present, the Path Vector cost
type MUST NOT be included in the "testable-cost-type-names" field type MUST NOT be included in the "testable-cost-type-names" field
unless specifically instructed by a future document. unless specifically instructed by a future document.
7.2.5. Uses 7.2.5. Uses
This member MUST include the resource ID of the network map based on This member MUST include the resource ID of the network map based on
which the PIDs are defined. If this resource supports "persistent- which the PIDs are defined. If this resource supports "persistent-
entity-id", it MUST also include the defining resources of persistent entity-id", it MUST also include the defining resources of persistent
ANEs that may appear in the response. ANEs that may appear in the response.
7.2.6. Response 7.2.6. Response
The response MUST indicate an error, using ALTO protocol error The response MUST indicate an error, using ALTO Protocol error
handling, as defined in Section 8.5 of [RFC7285], if the request is handling as defined in Section 8.5 of [RFC7285], if the request is
invalid. invalid.
The "Content-Type" header of the response MUST be "multipart/related" The "Content-Type" header field of the response MUST be "multipart/
as defined by [RFC2387] with the following parameters: related" as defined by [RFC2387], with the following parameters:
type: The type parameter is mandatory and MUST be "application/alto- type: The "type" parameter is mandatory and MUST be "application/
costmap+json". Note that [RFC2387] permits both parameters with alto-costmap+json". Note that [RFC2387] permits parameters both
and without the double quotes. with and without double quotes.
start: The start parameter is as defined in [RFC2387] and is start: The "start" parameter is as defined in [RFC2387] and is
optional. If present, it MUST have the same value as the optional. If present, it MUST have the same value as the
"Content-ID" header of the Path Vector part. "Content-ID" header field of the Path Vector part.
boundary: The boundary parameter is as defined in Section 5.1.1 of boundary: The "boundary" parameter is as defined in Section 5.1.1 of
[RFC2046] and is mandatory. [RFC2046] and is mandatory.
The body of the response MUST consist of two parts: The body of the response MUST consist of two parts:
* The Path Vector part MUST include "Content-ID" and "Content-Type" * The Path Vector part MUST include "Content-ID" and "Content-Type"
in its header. The "Content-Type" MUST be "application/alto- in its header. The "Content-Type" MUST be "application/alto-
costmap+json". The value of "Content-ID" MUST have the same costmap+json". The value of "Content-ID" MUST have the same
format as the Part Content ID as specified in Section 6.6. format as the Part Content ID as specified in Section 6.6.
The body of the Path Vector part MUST be a JSON object with the The body of the Path Vector part MUST be a JSON object with the
same format as defined in Section 11.2.3.6 of [RFC7285] when the same format as that defined in Section 11.2.3.6 of [RFC7285] when
"cost-type" field is present in the input parameters and MUST be a the "cost-type" field is present in the input parameters and MUST
JSON object with the same format as defined in Section 4.1.3 of be a JSON object with the same format as that defined in
[RFC8189] if the "multi-cost-types" field is present. The JSON Section 4.1.3 of [RFC8189] if the "multi-cost-types" field is
object MUST include the "vtag" field in the "meta" field, which present. The JSON object MUST include the "vtag" field in the
provides the version tag of the returned CostMapData. The "meta" field, which provides the version tag of the returned
resource ID of the version tag MUST follow the format of CostMapData object. The resource ID of the version tag MUST
follow the format of
resource-id '.' part-resource-id resource-id '.' part-resource-id
where "resource-id" is the resource Id of the Path Vector where "resource-id" is the resource ID of the Path Vector resource
resource, and "part-resource-id" has the same value as the PART- and "part-resource-id" has the same value as the PART-RESOURCE-ID
RESOURCE-ID in the "Content-ID" of the Path Vector part. The in the "Content-ID" of the Path Vector part. The "meta" field
"meta" field MUST also include the "dependent-vtags" field, whose MUST also include the "dependent-vtags" field, whose value is a
value is a single-element array to indicate the version tag of the single-element array to indicate the version tag of the network
network map used, where the network map is specified in the "uses" map used, where the network map is specified in the "uses"
attribute of the multipart Filtered Cost Map resource in IRD. attribute of the multipart filtered cost map resource in the IRD.
* The Unified Property Map part MUST also include "Content-ID" and * The entity property map part MUST also include "Content-ID" and
"Content-Type" in its header. The "Content-Type" MUST be "Content-Type" in its header. The "Content-Type" MUST be
"application/alto-propmap+json". The value of "Content-ID" MUST "application/alto-propmap+json". The value of "Content-ID" MUST
have the same format as the Part Content ID as specified in have the same format as the Part Content ID as specified in
Section 6.6. Section 6.6.
The body of the Unified Property Map part is a JSON object with The body of the entity property map part is a JSON object with the
the same format as defined in Section 7.6 of same format as that defined in Section 7.6 of [RFC9240]. The JSON
[I-D.ietf-alto-unified-props-new]. The JSON object MUST include object MUST include the "dependent-vtags" field in the "meta"
the "dependent-vtags" field in the "meta" field. The value of the field. The value of the "dependent-vtags" field MUST be an array
"dependent-vtags" field MUST be an array of VersionTag objects as of VersionTag objects as defined by Section 10.3 of [RFC7285].
defined by Section 10.3 of [RFC7285]. The "vtag" of the Path The "vtag" of the Path Vector part MUST be included in the
Vector part MUST be included in the "dependent-vtags". If "dependent-vtags" field. If "persistent-entity-id" is requested,
"persistent-entity-id" is requested, the version tags of the the version tags of the dependent resources that may expose the
dependent resources that may expose the entities in the response entities in the response MUST also be included.
MUST also be included.
The PropertyMapData has one member for each ANEName that appears The PropertyMapData object has one member for each ANEName that
in the Path Vector part, which is an entity identifier belonging appears in the Path Vector part, which is an entity identifier
to the self-defined entity domain as defined in Section 5.1.2.3 of belonging to the self-defined entity domain as defined in
[I-D.ietf-alto-unified-props-new]. The EntityProps for each ANE Section 5.1.2.3 of [RFC9240]. The EntityProps object for each ANE
has one member for each property that is both 1) associated with has one member for each property that is both 1) associated with
the ANE, and 2) specified in the "ane-property-names" in the the ANE and 2) specified in the "ane-property-names" field in the
request. If the Path Vector cost type is not included in the request. If the Path Vector cost type is not included in the
"cost-type" field or the "multi-cost-type" field, the "property- "cost-type" field or the "multi-cost-type" field, the "property-
map" field MUST be present and the value MUST be an empty object map" field MUST be present and the value MUST be an empty object
({}). ({}).
A complete and valid response MUST include both the Path Vector part A complete and valid response MUST include both the Path Vector part
and the Property Map part in the multipart message. If any part is and the property map part in the multipart message. If any part is
NOT present, the client MUST discard the received information and *not* present, the client MUST discard the received information and
send another request if necessary. send another request if necessary.
According to [RFC2387], the Path Vector part, whose media type is the The Path Vector part, whose media type is the same as the "type"
same as the "type" parameter of the multipart response message, is parameter of the multipart response message, is the root body part as
the root object. Thus, it is the element the application processes defined in [RFC2387]. Thus, it is the element that the application
first. Even though the "start" parameter allows it to be placed processes first. Even though the "start" parameter allows it to be
anywhere in the part sequence, it is RECOMMENDED that the parts placed anywhere in the part sequence, it is RECOMMENDED that the
arrive in the same order as they are processed, i.e., the Path Vector parts arrive in the same order as they are processed, i.e., the Path
part is always put as the first part, followed by the Property Map Vector part is always placed as the first part, followed by the
part. When doing so, an ALTO server MAY choose not to set the property map part. When doing so, an ALTO server MAY choose not to
"start" parameter, which implies the first part is the root object. set the "start" parameter, which implies that the first part is the
object root.
Example: Consider the network in Figure 1. The response of the Example: Consider the network in Figure 1. The response to the
example request in Section 7.2.3 is as follows, where "ANE1" example request in Section 7.2.3 is as follows, where "ANE1"
represents the aggregation of all the switches in the network. represents the aggregation of all the switches in the network.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Length: 859 Content-Length: 911
Content-Type: multipart/related; boundary=example-1; Content-Type: multipart/related; boundary=example-1;
type=application/alto-costmap+json type=application/alto-costmap+json
--example-1 --example-1
Content-ID: <costmap@alto.example.com> Content-ID: <costmap@alto.example.com>
Content-Type: application/alto-costmap+json Content-Type: application/alto-costmap+json
{ {
"meta": { "meta": {
"vtag": { "vtag": {
skipping to change at page 33, line 29 skipping to change at line 1401
}, },
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "my-default-networkmap", "resource-id": "my-default-networkmap",
"tag": "75ed013b3cb58f896e839582504f6228" "tag": "75ed013b3cb58f896e839582504f6228"
} }
], ],
"cost-type": { "cost-mode": "array", "cost-metric": "ane-path" } "cost-type": { "cost-mode": "array", "cost-metric": "ane-path" }
}, },
"cost-map": { "cost-map": {
"PID1": { "PID2": ["ANE1"] } "PID1": { "PID2": [ "ANE1" ] }
} }
} }
--example-1 --example-1
Content-ID: <propmap@alto.example.com> Content-ID: <propmap@alto.example.com>
Content-Type: application/alto-propmap+json Content-Type: application/alto-propmap+json
{ {
"meta": { "meta": {
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "filtered-cost-map-pv.costmap", "resource-id": "filtered-cost-map-pv.costmap",
"tag": "fb20b76204814e9db37a51151faaaef2" "tag": "fb20b76204814e9db37a51151faaaef2"
} }
] ]
}, },
"property-map": { "property-map": {
".ane:ANE1": { "max-reservable-bandwidth": 100000000 } ".ane:ANE1": { "max-reservable-bandwidth": 100000000 }
} }
} }
--example-1
7.3. Multipart Endpoint Cost Service for Path Vector 7.3. Multipart Endpoint Cost Service for Path Vector
This document introduces a new ALTO resource called multipart This document introduces a new ALTO resource called the "multipart
Endpoint Cost Service, which allows an ALTO server to provide other Endpoint Cost Service", which allows an ALTO server to provide other
ALTO resources associated with the Endpoint Cost Service resource in ALTO resources associated with the Endpoint Cost Service resource in
the same response. the same response.
7.3.1. Media Type 7.3.1. Media Type
The media type of the multipart Endpoint Cost Service resource is The media type of the multipart Endpoint Cost Service resource is
"multipart/related" and the required "type" parameter MUST have a "multipart/related", and the required "type" parameter MUST have a
value of "application/alto-endpointcost+json". value of "application/alto-endpointcost+json".
7.3.2. HTTP Method 7.3.2. HTTP Method
The multipart Endpoint Cost Service resource is requested using the The multipart Endpoint Cost Service resource is requested using the
HTTP POST method. HTTP POST method.
7.3.3. Accept Input Parameters 7.3.3. Accept Input Parameters
The input parameters of the multipart Endpoint Cost Service resource The input parameters of the multipart Endpoint Cost Service resource
are supplied in the body of an HTTP POST request. This document are supplied in the body of an HTTP POST request. This document
extends the input parameters to an Endpoint Cost Service, which is extends the input parameters to an Endpoint Cost Service, which is
defined as a JSON object of type ReqEndpointCost in Section 4.2.2 of defined as a JSON object of type ReqEndpointCostMap in Section 4.2.2
[RFC8189], with a data format indicated by the media type of [RFC8189], with a data format indicated by the media type
"application/alto-endpointcostparams+json", which is a JSON object of "application/alto-endpointcostparams+json", which is a JSON object of
type PVReqEndpointCost: type PVReqEndpointCostMap:
object { object {
[EntityPropertyName ane-property-names<0..*>;] [EntityPropertyName ane-property-names<0..*>;]
} PVReqEndpointcost : ReqEndpointcostMap; } PVReqEndpointCostMap : ReqEndpointCostMap;
with fields: with field:
ane-property-names: This document defines the "ane-property-names" ane-property-names: This document defines the "ane-property-names"
in PVReqEndpointcost as the same as in PVReqFilteredCostMap. See field in PVReqEndpointCostMap as being the same as in
Section 7.2.3. PVReqFilteredCostMap. See Section 7.2.3.
Example: Consider the network in Figure 1. If an ALTO client wants Example: Consider the network in Figure 1. If an ALTO client wants
to query the "max-reservable-bandwidth" between eh1 and eh2, it can to query the "max-reservable-bandwidth" setting between "eh1" and
submit the following request. "eh2", it can submit the following request.
POST /ecs/pv HTTP/1.1 POST /ecs/pv HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: multipart/related;type=application/alto-endpointcost+json, Accept: multipart/related;type=application/alto-endpointcost+json,
application/alto-error+json application/alto-error+json
Content-Length: 227 Content-Length: 238
Content-Type: application/alto-endpointcostparams+json Content-Type: application/alto-endpointcostparams+json
{ {
"cost-type": { "cost-type": {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, },
"endpoints": { "endpoints": {
"srcs": [ "ipv4:192.0.2.2" ], "srcs": [ "ipv4:192.0.2.2" ],
"dsts": [ "ipv4:192.0.2.18" ] "dsts": [ "ipv4:192.0.2.18" ]
}, },
"ane-property-names": [ "max-reservable-bandwidth" ] "ane-property-names": [ "max-reservable-bandwidth" ]
} }
7.3.4. Capabilities 7.3.4. Capabilities
The capabilities of the multipart Endpoint Cost Service resource are The capabilities of the multipart Endpoint Cost Service resource are
defined by a JSON object of type PVEndpointcostCapabilities, which is defined by a JSON object of type PVEndpointCostCapabilities, which is
defined as the same as PVFilteredCostMapCapabilities. See defined as being the same as PVFilteredCostMapCapabilities. See
Section 7.2.4. Section 7.2.4.
7.3.5. Uses 7.3.5. Uses
If this resource supports "persistent-entity-id", it MUST also If this resource supports "persistent-entity-id", it MUST also
include the defining resources of persistent ANEs that may appear in include the defining resources of persistent ANEs that may appear in
the response. the response.
7.3.6. Response 7.3.6. Response
The response MUST indicate an error, using ALTO protocol error The response MUST indicate an error, using ALTO Protocol error
handling, as defined in Section 8.5 of [RFC7285], if the request is handling as defined in Section 8.5 of [RFC7285], if the request is
invalid. invalid.
The "Content-Type" header of the response MUST be "multipart/related" The "Content-Type" header field of the response MUST be "multipart/
as defined by [RFC7285] with the following parameters: related" as defined by [RFC2387], with the following parameters:
type: The type parameter MUST be "application/alto- type: The "type" parameter MUST be "application/alto-
endpointcost+json" and is mandatory. endpointcost+json" and is mandatory.
start: The start parameter is as defined in Section 7.2.6. start: The "start" parameter is as defined in Section 7.2.6.
boundary: The boundary parameter is as defined in Section 5.1.1 of boundary: The "boundary" parameter is as defined in Section 5.1.1 of
[RFC2046] and is mandatory. [RFC2046] and is mandatory.
The body MUST consist of two parts: The body of the response MUST consist of two parts:
* The Path Vector part MUST include "Content-ID" and "Content-Type" * The Path Vector part MUST include "Content-ID" and "Content-Type"
in its header. The "Content-Type" MUST be "application/alto- in its header. The "Content-Type" MUST be "application/alto-
endpointcost+json". The value of "Content-ID" MUST have the same endpointcost+json". The value of "Content-ID" MUST have the same
format as the Part Content ID as specified in Section 6.6. format as the Part Content ID as specified in Section 6.6.
The body of the Path Vector part MUST be a JSON object with the The body of the Path Vector part MUST be a JSON object with the
same format as defined in Section 11.5.1.6 of [RFC7285] when the same format as that defined in Section 11.5.1.6 of [RFC7285] when
"cost-type" field is present in the input parameters and MUST be a the "cost-type" field is present in the input parameters and MUST
JSON object with the same format as defined in Section 4.2.3 of be a JSON object with the same format as that defined in
[RFC8189] if the "multi-cost-types" field is present. The JSON Section 4.2.3 of [RFC8189] if the "multi-cost-types" field is
object MUST include the "vtag" field in the "meta" field, which present. The JSON object MUST include the "vtag" field in the
provides the version tag of the returned EndpointCostMapData. The "meta" field, which provides the version tag of the returned
resource ID of the version tag MUST follow the format of EndpointCostMapData object. The resource ID of the version tag
MUST follow the format of
resource-id '.' part-resource-id resource-id '.' part-resource-id
where "resource-id" is the resource Id of the Path Vector where "resource-id" is the resource ID of the Path Vector resource
resource, and "part-resource-id" has the same value as the PART- and "part-resource-id" has the same value as the PART-RESOURCE-ID
RESOURCE-ID in the "Content-ID" of the Path Vector part. in the "Content-ID" of the Path Vector part.
* The Unified Property Map part MUST also include "Content-ID" and * The entity property map part MUST also include "Content-ID" and
"Content-Type" in its header. The "Content-Type" MUST be "Content-Type" in its header. The "Content-Type" MUST be
"application/alto-propmap+json". The value of "Content-ID" MUST "application/alto-propmap+json". The value of "Content-ID" MUST
have the same format as the Part Content ID as specified in have the same format as the Part Content ID as specified in
Section 6.6. Section 6.6.
The body of the Unified Property Map part MUST be a JSON object The body of the entity property map part MUST be a JSON object
with the same format as defined in Section 7.6 of with the same format as that defined in Section 7.6 of [RFC9240].
[I-D.ietf-alto-unified-props-new]. The JSON object MUST include The JSON object MUST include the "dependent-vtags" field in the
the "dependent-vtags" field in the "meta" field. The value of the "meta" field. The value of the "dependent-vtags" field MUST be an
"dependent-vtags" field MUST be an array of VersionTag objects as array of VersionTag objects as defined by Section 10.3 of
defined by Section 10.3 of [RFC7285]. The "vtag" of the Path [RFC7285]. The "vtag" of the Path Vector part MUST be included in
Vector part MUST be included in the "dependent-vtags". If the "dependent-vtags" field. If "persistent-entity-id" is
"persistent-entity-id" is requested, the version tags of the requested, the version tags of the dependent resources that may
dependent resources that may expose the entities in the response expose the entities in the response MUST also be included.
MUST also be included.
The PropertyMapData has one member for each ANEName that appears The PropertyMapData object has one member for each ANEName that
in the Path Vector part, which is an entity identifier belonging appears in the Path Vector part, which is an entity identifier
to the self-defined entity domain as defined in Section 5.1.2.3 of belonging to the self-defined entity domain as defined in
[I-D.ietf-alto-unified-props-new]. The EntityProps for each ANE Section 5.1.2.3 of [RFC9240]. The EntityProps object for each ANE
has one member for each property that is both 1) associated with has one member for each property that is both 1) associated with
the ANE, and 2) specified in the "ane-property-names" in the the ANE and 2) specified in the "ane-property-names" field in the
request. If the Path Vector cost type is not included in the request. If the Path Vector cost type is not included in the
"cost-type" field or the "multi-cost-type" field, the "property- "cost-type" field or the "multi-cost-type" field, the "property-
map" field MUST be present and the value MUST be an empty object map" field MUST be present and the value MUST be an empty object
({}). ({}).
A complete and valid response MUST include both the Path Vector part A complete and valid response MUST include both the Path Vector part
and the Property Map part in the multipart message. If any part is and the property map part in the multipart message. If any part is
NOT present, the client MUST discard the received information and *not* present, the client MUST discard the received information and
send another request if necessary. send another request if necessary.
According to [RFC2387], the Path Vector part, whose media type is the The Path Vector part, whose media type is the same as the "type"
same as the "type" parameter of the multipart response message, is parameter of the multipart response message, is the root body part as
the root object. Thus, it is the element the application processes defined in [RFC2387]. Thus, it is the element that the application
first. Even though the "start" parameter allows it to be placed processes first. Even though the "start" parameter allows it to be
anywhere in the part sequence, it is RECOMMENDED that the parts placed anywhere in the part sequence, it is RECOMMENDED that the
arrive in the same order as they are processed, i.e., the Path Vector parts arrive in the same order as they are processed, i.e., the Path
part is always put as the first part, followed by the Property Map Vector part is always placed as the first part, followed by the
part. When doing so, an ALTO server MAY choose not to set the property map part. When doing so, an ALTO server MAY choose not to
"start" parameter, which implies the first part is the root object. set the "start" parameter, which implies that the first part is the
object root.
Example: Consider the network in Figure 1. The response of the Example: Consider the network in Figure 1. The response to the
example request in Section 7.3.3 is as follows. example request in Section 7.3.3 is as follows.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Length: 845 Content-Length: 899
Content-Type: multipart/related; boundary=example-1; Content-Type: multipart/related; boundary=example-1;
type=application/alto-endpointcost+json type=application/alto-endpointcost+json
--example-1 --example-1
Content-ID: <ecs@alto.example.com> Content-ID: <ecs@alto.example.com>
Content-Type: application/alto-endpointcost+json Content-Type: application/alto-endpointcost+json
{ {
"meta": { "meta": {
"vtag": { "vtag": {
skipping to change at page 38, line 29 skipping to change at line 1607
}, },
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "my-default-networkmap", "resource-id": "my-default-networkmap",
"tag": "677fe5f4066848d282ece213a84f9429" "tag": "677fe5f4066848d282ece213a84f9429"
} }
], ],
"cost-type": { "cost-mode": "array", "cost-metric": "ane-path" } "cost-type": { "cost-mode": "array", "cost-metric": "ane-path" }
}, },
"cost-map": { "cost-map": {
"ipv4:192.0.2.2": { "ipv4:192.0.2.18": ["ANE1"] } "ipv4:192.0.2.2": { "ipv4:192.0.2.18": [ "ANE1" ] }
} }
} }
--example-1 --example-1
Content-ID: <propmap@alto.example.com> Content-ID: <propmap@alto.example.com>
Content-Type: application/alto-propmap+json Content-Type: application/alto-propmap+json
{ {
"meta": { "meta": {
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "ecs-pv.ecs", "resource-id": "ecs-pv.ecs",
"tag": "ec137bb78118468c853d5b622ac003f1" "tag": "ec137bb78118468c853d5b622ac003f1"
} }
] ]
}, },
"property-map": { "property-map": {
".ane:ANE1": { "max-reservable-bandwidth": 100000000 } ".ane:ANE1": { "max-reservable-bandwidth": 100000000 }
} }
} }
--example-1
8. Examples 8. Examples
This section lists some examples of Path Vector queries and the This section lists some examples of Path Vector queries and the
corresponding responses. Some long lines are truncated for better corresponding responses. Some long lines are truncated for better
readability. readability.
8.1. Sample Setup 8.1. Sample Setup
Figure 10 illustrates the network properties and thus the message
contents. There are three subnetworks (NET1, NET2, and NET3) and two
interconnection links (L1 and L2). It is assumed that each
subnetwork has sufficiently large bandwidth to be reserved.
----- L1 ----- L1
/ /
PID1 +----------+ 10 Gbps +----------+ PID3 PID1 +----------+ 10 Gbps +----------+ PID3
192.0.2.0/28+-+ +------+ +---------+ +--+192.0.2.32/28 192.0.2.0/28+-+ +------+ +---------+ +--+192.0.2.32/28
| | MEC1 | | | | 2001:db8::3:0/16 | | MEC1 | | | | 2001:db8::3:0/16
| +------+ | +-----+ | | +------+ | +-----+ |
PID2 | | | +----------+ PID2 | | | +----------+
192.0.2.16/28+-+ | | NET3 192.0.2.16/28+-+ | | NET3
| | | 15 Gbps | | | 15 Gbps
| | | \ | | | \
skipping to change at page 39, line 34 skipping to change at line 1663
NET1 | NET1 |
+----------+ +----------+
| +------+ | PID4 | +------+ | PID4
| | MEC2 | +--+192.0.2.48/28 | | MEC2 | +--+192.0.2.48/28
| +------+ | 2001:db8::4:0/16 | +------+ | 2001:db8::4:0/16
+----------+ +----------+
NET2 NET2
Figure 10: Examples of ANE Properties Figure 10: Examples of ANE Properties
In this document, Figure 10 is used to illustrate the message
contents. There are 3 sub-networks (NET1, NET2 and NET3) and two
interconnection links (L1 and L2). It is assumed that each sub-
network has sufficiently large bandwidth to be reserved.
8.2. Information Resource Directory 8.2. Information Resource Directory
To give a comprehensive example of the extension defined in this To give a comprehensive example of the extension defined in this
document, we consider the network in Figure 10. Assume that the ALTO document, we consider the network in Figure 10. Assume that the ALTO
server provides the following information resources: server provides the following information resources:
* "my-default-networkmap": A Network Map resource which contains the "my-default-networkmap": A network map resource that contains the
PIDs in the network. PIDs in the network.
* "filtered-cost-map-pv": A Multipart Filtered Cost Map resource for "filtered-cost-map-pv": A multipart filtered cost map resource for
Path Vector, which exposes the "max-reservable-bandwidth" property the Path Vector. Exposes the "max-reservable-bandwidth" property
for the PIDs in "my-default-networkmap". for the PIDs in "my-default-networkmap".
* "ane-props": A filtered Unified Property resource that exposes the "ane-props": A filtered entity property resource that exposes the
information for persistent ANEs in the network. information for persistent ANEs in the network.
* "endpoint-cost-pv": A Multipart Endpoint Cost Service for Path "endpoint-cost-pv": A multipart Endpoint Cost Service for the Path
Vector, which exposes the "max-reservable-bandwidth" and the Vector. Exposes the "max-reservable-bandwidth" and "persistent-
"persistent-entity-id" properties. entity-id" properties.
* "update-pv": An Update Stream service, which provides the "update-pv": An update stream service that provides the incremental
incremental update service for the "endpoint-cost-pv" service. update service for the "endpoint-cost-pv" service.
* "multicost-pv": A Multipart Endpoint Cost Service with both Multi- "multicost-pv": A multipart Endpoint Cost Service with both the
Cost and Path Vector. Multi-Cost extension and Path Vector extension enabled.
Below is the Information Resource Directory of the example ALTO Below is the IRD of the example ALTO server. To enable the extension
server. To enable the extension defined in this document, the "path- defined in this document, the Path Vector cost type (Section 6.5),
vector" cost type (Section 6.5) is defined in the "cost-types" of the represented by "path-vector" below, is defined in the "cost-types" of
"meta" field, and is included in the "cost-type-names" of resources the "meta" field and is included in the "cost-type-names" of
"filtered-cost-map-pv" and "endpoint-cost-pv". resources "filtered-cost-map-pv" and "endpoint-cost-pv".
{ {
"meta": { "meta": {
"cost-types": { "cost-types": {
"path-vector": { "path-vector": {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, },
"num-rc": { "num-rc": {
"cost-mode": "numerical", "cost-mode": "numerical",
skipping to change at page 42, line 4 skipping to change at line 1772
"cost-type-names": [ "path-vector", "num-rc" ], "cost-type-names": [ "path-vector", "num-rc" ],
"max-cost-types": 2, "max-cost-types": 2,
"testable-cost-type-names": [ "num-rc" ], "testable-cost-type-names": [ "num-rc" ],
"ane-property-names": [ "ane-property-names": [
"max-reservable-bandwidth", "persistent-entity-id" "max-reservable-bandwidth", "persistent-entity-id"
] ]
}, },
"uses": [ "ane-props" ] "uses": [ "ane-props" ]
} }
} }
} }
8.3. Multipart Filtered Cost Map 8.3. Multipart Filtered Cost Map
The following examples demonstrate the request to the "filtered-cost- The following examples demonstrate the request to the "filtered-cost-
map-pv" resource and the corresponding response. map-pv" resource and the corresponding response.
The request uses the "path-vector" cost type in the "cost-type" The request uses the "path-vector" cost type in the "cost-type"
field. The "ane-property-names" field is missing, indicating that field. The "ane-property-names" field is missing, indicating that
the client only requests for the Path Vector but not the ANE the client only requests the Path Vector and not the ANE properties.
properties.
The response consists of two parts. The first part returns the array The response consists of two parts:
of ANEName for each source and destination pair. There are two ANEs,
where "L1" represents the interconnection link L1, and "L2"
represents the interconnection link L2.
The second part returns an empty Property Map. Note that the ANE * The first part returns the array of data type ANEName for each
entries are omitted since they have no properties (See Section 3.1 of source and destination pair. There are two ANEs, where "L1"
[I-D.ietf-alto-unified-props-new]). represents interconnection link L1 and "L2" represents
interconnection link L2.
* The second part returns the property map. Note that the
properties of the ANE entries are equal to the literal string "{}"
(see Section 8.3 of [RFC9240]).
POST /costmap/pv HTTP/1.1 POST /costmap/pv HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: multipart/related;type=application/alto-costmap+json, Accept: multipart/related;type=application/alto-costmap+json,
application/alto-error+json application/alto-error+json
Content-Length: 153 Content-Length: 163
Content-Type: application/alto-costmapfilter+json Content-Type: application/alto-costmapfilter+json
{ {
"cost-type": { "cost-type": {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, },
"pids": { "pids": {
"srcs": [ "PID1" ], "srcs": [ "PID1" ],
"dsts": [ "PID3", "PID4" ] "dsts": [ "PID3", "PID4" ]
} }
} }
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Length: 855 Content-Length: 952
Content-Type: multipart/related; boundary=example-1; Content-Type: multipart/related; boundary=example-1;
type=application/alto-costmap+json type=application/alto-costmap+json
--example-1 --example-1
Content-ID: <costmap@alto.example.com> Content-ID: <costmap@alto.example.com>
Content-Type: application/alto-costmap+json Content-Type: application/alto-costmap+json
{ {
"meta": { "meta": {
"vtag": { "vtag": {
"resource-id": "filtered-cost-map-pv.costmap", "resource-id": "filtered-cost-map-pv.costmap",
"tag": "d827f484cb66ce6df6b5077cb8562b0a" "tag": "d827f484cb66ce6df6b5077cb8562b0a"
}, },
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "my-default-networkmap", "resource-id": "my-default-networkmap",
"tag": "c04bc5da49534274a6daeee8ea1dec62" "tag": "c04bc5da49534274a6daeee8ea1dec62"
skipping to change at page 43, line 42 skipping to change at line 1859
{ {
"meta": { "meta": {
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "filtered-cost-map-pv.costmap", "resource-id": "filtered-cost-map-pv.costmap",
"tag": "d827f484cb66ce6df6b5077cb8562b0a" "tag": "d827f484cb66ce6df6b5077cb8562b0a"
} }
] ]
}, },
"property-map": { "property-map": {
".ane:L1": {},
".ane:L2": {}
} }
} }
--example-1
8.4. Multipart Endpoint Cost Service Resource 8.4. Multipart Endpoint Cost Service Resource
The following examples demonstrate the request to the "endpoint-cost- The following examples demonstrate the request to the "endpoint-cost-
pv" resource and the corresponding response. pv" resource and the corresponding response.
The request uses the Path Vector cost type in the "cost-type" field, The request uses the "path-vector" cost type in the "cost-type" field
and queries the Maximum Reservable Bandwidth ANE property and the and queries the maximum reservable bandwidth ANE property and the
Persistent Entity property for two IPv4 source and destination pairs persistent entity ID property for two IPv4 source and destination
(192.0.2.34 -> 192.0.2.2 and 192.0.2.34 -> 192.0.2.50) and one IPv6 pairs (192.0.2.34 -> 192.0.2.2 and 192.0.2.34 -> 192.0.2.50) and one
source and destination pair (2001:db8::3:1 -> 2001:db8::4:1). IPv6 source and destination pair (2001:db8::3:1 -> 2001:db8::4:1).
The response consists of two parts. The first part returns the array The response consists of two parts:
of ANEName for each valid source and destination pair. As one can
see in Figure 10, flow 192.0.2.34 -> 192.0.2.2 traverses NET2, L1 and
NET1, and flows 192.0.2.34 -> 192.0.2.50 and 2001:db8::3:1 ->
2001:db8::4:1 traverse NET2, L2 and NET3.
The second part returns the requested properties of ANEs. Assume * The first part returns the array of data type ANEName for each
NET1, NET2 and NET3 has sufficient bandwidth and their "max- valid source and destination pair. As one can see in Figure 10,
reservable-bandwidth" values are set to a sufficiently large number flow 192.0.2.34 -> 192.0.2.2 traverses NET3, L1, and NET1; and
(50 Gbps in this case). On the other hand, assume there are no prior flows 192.0.2.34 -> 192.0.2.50 and 2001:db8::3:1 -> 2001:db8::4:1
reservation on L1 and L2, and their "max-reservable-bandwidth" values traverse NET2, L2, and NET3.
are the corresponding link capacity (10 Gbps for L1 and 15 Gbps for
L2). * The second part returns the requested properties of ANEs. Assume
that NET1, NET2, and NET3 have sufficient bandwidth and their
"max-reservable-bandwidth" values are set to a sufficiently large
number (50 Gbps in this case). On the other hand, assume that
there are no prior reservations on L1 and L2 and their "max-
reservable-bandwidth" values are the corresponding link capacity
(10 Gbps for L1 and 15 Gbps for L2).
Both NET1 and NET2 have a mobile edge deployed, i.e., MEC1 in NET1 Both NET1 and NET2 have a mobile edge deployed, i.e., MEC1 in NET1
and MEC2 in NET2. Assume the ANEName for MEC1 and MEC2 are "MEC1" and MEC2 in NET2. Assume that the ANEName values for MEC1 and MEC2
and "MEC2" and their properties can be retrieved from the Property are "MEC1" and "MEC2" and their properties can be retrieved from the
Map "ane-props". Thus, the "persistent-entity-id" property of NET1 property map "ane-props". Thus, the "persistent-entity-id" property
and NET3 are "ane-props.ane:MEC1" and "ane-props.ane:MEC2" values for NET1 and NET2 are "ane-props.ane:MEC1" and "ane-
respectively. props.ane:MEC2", respectively.
POST /endpointcost/pv HTTP/1.1 POST /endpointcost/pv HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: multipart/related; Accept: multipart/related;
type=application/alto-endpointcost+json, type=application/alto-endpointcost+json,
application/alto-error+json application/alto-error+json
Content-Length: 362 Content-Length: 383
Content-Type: application/alto-endpointcostparams+json Content-Type: application/alto-endpointcostparams+json
{ {
"cost-type": { "cost-type": {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, },
"endpoints": { "endpoints": {
"srcs": [ "srcs": [
"ipv4:192.0.2.34", "ipv4:192.0.2.34",
skipping to change at page 45, line 36 skipping to change at line 1930
"ipv6:2001:db8::4:1" "ipv6:2001:db8::4:1"
] ]
}, },
"ane-property-names": [ "ane-property-names": [
"max-reservable-bandwidth", "max-reservable-bandwidth",
"persistent-entity-id" "persistent-entity-id"
] ]
} }
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Length: 1432 Content-Length: 1508
Content-Type: multipart/related; boundary=example-2; Content-Type: multipart/related; boundary=example-2;
type=application/alto-endpointcost+json type=application/alto-endpointcost+json
--example-2 --example-2
Content-ID: <ecs@alto.example.com> Content-ID: <ecs@alto.example.com>
Content-Type: application/alto-endpointcost+json Content-Type: application/alto-endpointcost+json
{ {
"meta": { "meta": {
"vtags": { "vtags": {
skipping to change at page 47, line 4 skipping to change at line 1995
".ane:NET3": { ".ane:NET3": {
"max-reservable-bandwidth": 50000000000 "max-reservable-bandwidth": 50000000000
}, },
".ane:L1": { ".ane:L1": {
"max-reservable-bandwidth": 10000000000 "max-reservable-bandwidth": 10000000000
}, },
".ane:L2": { ".ane:L2": {
"max-reservable-bandwidth": 15000000000 "max-reservable-bandwidth": 15000000000
} }
} }
} }
--example-2
Under certain scenarios where the traversal order is not crucial, an In certain scenarios where the traversal order is not crucial, an
ALTO server implementation may choose to not follow strictly the ALTO server implementation may choose not to strictly follow the
physical traversal order and may even obfuscate the order physical traversal order and may even obfuscate the order
intentionally to preserve its own privacy or conform to its own intentionally to preserve its own privacy or conform to its own
policies. For example, an ALTO server may choose to aggregate NET1 policies. For example, an ALTO server may choose to aggregate NET1
and L1 as a new ANE with ANE name "AGGR1", and aggregate NET2 and L2 and L1 as a new ANE with ANE name "AGGR1" and aggregate NET2 and L2
as a new ANE with ANE name "AGGR2". The "max-reservable-bandwidth" as a new ANE with ANE name "AGGR2". The "max-reservable-bandwidth"
of "AGGR1" takes the value of L1, which is smaller than that of NET1, property of "AGGR1" takes the value of L1, which is smaller than that
and the "persistent-entity-id" of "AGGR1" takes the value of NET1. of NET1, and the "persistent-entity-id" property of "AGGR1" takes the
The properties of "AGGR2" are computed in a similar way and the value of NET1. The properties of "AGGR2" are computed in a similar
obfuscated response is as shown below. Note that the obfuscation of way; the obfuscated response is as shown below. Note that the
Path Vector responses is implementation-specific and is out of the obfuscation of Path Vector responses is implementation specific and
scope of this document, and developers may refer to Section 11 for is out of scope for this document. Developers may refer to
further references. Section 11 for further references.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Length: 1263 Content-Length: 1333
Content-Type: multipart/related; boundary=example-2; Content-Type: multipart/related; boundary=example-2;
type=application/alto-endpointcost+json type=application/alto-endpointcost+json
--example-2 --example-2
Content-ID: <ecs@alto.example.com> Content-ID: <ecs@alto.example.com>
Content-Type: application/alto-endpointcost+json Content-Type: application/alto-endpointcost+json
{ {
"meta": { "meta": {
"vtags": { "vtags": {
skipping to change at page 48, line 34 skipping to change at line 2074
}, },
".ane:AGGR2": { ".ane:AGGR2": {
"max-reservable-bandwidth": 15000000000, "max-reservable-bandwidth": 15000000000,
"persistent-entity-id": "ane-props.ane:MEC2" "persistent-entity-id": "ane-props.ane:MEC2"
}, },
".ane:NET3": { ".ane:NET3": {
"max-reservable-bandwidth": 50000000000 "max-reservable-bandwidth": 50000000000
} }
} }
} }
--example-2
8.5. Incremental Updates 8.5. Incremental Updates
In this example, an ALTO client subscribes to the incremental update In this example, an ALTO client subscribes to the incremental update
for the multipart Endpoint Cost Service resource "endpoint-cost-pv". for the multipart Endpoint Cost Service resource "endpoint-cost-pv".
POST /updates/pv HTTP/1.1 POST /updates/pv HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: text/event-stream Accept: text/event-stream
Content-Type: application/alto-updatestreamparams+json Content-Type: application/alto-updatestreamparams+json
Content-Length: 112 Content-Length: 120
{ {
"add": { "add": {
"ecspvsub1": { "ecspvsub1": {
"resource-id": "endpoint-cost-pv", "resource-id": "endpoint-cost-pv",
"input": <ecs-input> "input": <ecs-input>
} }
} }
} }
Based on the server-side process defined in [RFC8895], the ALTO Based on the server-side process defined in [RFC8895], the ALTO
server will send the "control-uri" first using Server-Sent Event server will send the "control-uri" first, using a Server-Sent Event
(SSE), followed by the full response of the multipart message. (SSE) followed by the full response of the multipart message.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Connection: keep-alive Connection: keep-alive
Content-Type: text/event-stream Content-Type: text/event-stream
event: application/alto-updatestreamcontrol+json event: application/alto-updatestreamcontrol+json
data: {"control-uri": "https://alto.example.com/updates/streams/123"} data: {"control-uri": "https://alto.example.com/updates/streams/123"}
event: multipart/related;boundary=example-3; event: multipart/related;boundary=example-3;
type=application/alto-endpointcost+json,ecspvsub1 type=application/alto-endpointcost+json,ecspvsub1
skipping to change at page 50, line 5 skipping to change at line 2125
data: Content-ID: <propmap@alto.example.com> data: Content-ID: <propmap@alto.example.com>
data: Content-Type: application/alto-propmap+json data: Content-Type: application/alto-propmap+json
data: data:
data: <property-map-entry> data: <property-map-entry>
data: --example-3-- data: --example-3--
When the contents change, the ALTO server will publish the updates When the contents change, the ALTO server will publish the updates
for each node in this tree separately, based on Section 6.7.3 of for each node in this tree separately, based on Section 6.7.3 of
[RFC8895]. [RFC8895].
event: application/merge-patch+json, ecspvsub1.ecsmap@alto.example.com event: application/merge-patch+json,
data: <Merge patch for endpoint-cost-map-update> ecspvsub1.ecsmap@alto.example.com
data: <Merge patch for endpoint-cost-map-update>
event: application/merge-patch+json, ecspvsub1.propmap@alto.example.com event: application/merge-patch+json,
data: <Merge patch for property-map-update> ecspvsub1.propmap@alto.example.com
data: <Merge patch for property-map-update>
8.6. Multi-cost 8.6. Multi-Cost
The following examples demonstrate the request to the "multicost-pv" The following examples demonstrate the request to the "multicost-pv"
resource and the corresponding response. resource and the corresponding response.
The request asks for two cost types: the first is the Path Vector The request asks for two cost types: the first is the Path Vector
cost type, and the second is a numerical routing cost. It also cost type, and the second is a numerical routing cost. It also
queries the Maximum Reservable Bandwidth ANE property and the queries the maximum reservable bandwidth ANE property and the
Persistent Entity property for two IPv4 source and destination pairs persistent entity ID property for two IPv4 source and destination
(192.0.2.34 -> 192.0.2.2 and 192.0.2.34 -> 192.0.2.50) and one IPv6 pairs (192.0.2.34 -> 192.0.2.2 and 192.0.2.34 -> 192.0.2.50) and one
source and destination pair (2001:db8::3:1 -> 2001:db8::4:1). IPv6 source and destination pair (2001:db8::3:1 -> 2001:db8::4:1).
The response consists of two parts. The first part returns a The response consists of two parts:
JSONArray that contains two JSONValue for each requested source and
destination pair: the first JSONValue is a JSONArray of ANENames, * The first part returns a JSONArray that contains two JSONValue
which is the value of the Path Vector cost type, and the second entries for each requested source and destination pair: the first
JSONValue is a JSONNumber which is the value of the routing cost. JSONValue is a JSONArray of ANENames, which is the value of the
The second part contains a Property Map that maps the ANEs to their Path Vector cost type; and the second JSONValue is a JSONNumber,
requested properties. which is the value of the routing cost.
* The second part contains a property map that maps the ANEs to
their requested properties.
POST /endpointcost/mcpv HTTP/1.1 POST /endpointcost/mcpv HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: multipart/related; Accept: multipart/related;
type=application/alto-endpointcost+json, type=application/alto-endpointcost+json,
application/alto-error+json application/alto-error+json
Content-Length: 433 Content-Length: 454
Content-Type: application/alto-endpointcostparams+json Content-Type: application/alto-endpointcostparams+json
{ {
"multi-cost-types": [ "multi-cost-types": [
{ "cost-mode": "array", "cost-metric": "ane-path" }, { "cost-mode": "array", "cost-metric": "ane-path" },
{ "cost-mode": "numerical", "cost-metric": "routingcost" } { "cost-mode": "numerical", "cost-metric": "routingcost" }
], ],
"endpoints": { "endpoints": {
"srcs": [ "srcs": [
"ipv4:192.0.2.34", "ipv4:192.0.2.34",
skipping to change at page 51, line 36 skipping to change at line 2187
"ipv6:2001:db8::4:1" "ipv6:2001:db8::4:1"
] ]
}, },
"ane-property-names": [ "ane-property-names": [
"max-reservable-bandwidth", "max-reservable-bandwidth",
"persistent-entity-id" "persistent-entity-id"
] ]
} }
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Length: 1350 Content-Length: 1419
Content-Type: multipart/related; boundary=example-4; Content-Type: multipart/related; boundary=example-4;
type=application/alto-endpointcost+json type=application/alto-endpointcost+json
--example-4 --example-4
Content-ID: <ecs@alto.example.com> Content-ID: <ecs@alto.example.com>
Content-Type: application/alto-endpointcost+json Content-Type: application/alto-endpointcost+json
{ {
"meta": { "meta": {
"vtags": { "vtags": {
skipping to change at page 52, line 48 skipping to change at line 2247
}, },
".ane:AGGR2": { ".ane:AGGR2": {
"max-reservable-bandwidth": 15000000000, "max-reservable-bandwidth": 15000000000,
"persistent-entity-id": "ane-props.ane:MEC2" "persistent-entity-id": "ane-props.ane:MEC2"
}, },
".ane:NET3": { ".ane:NET3": {
"max-reservable-bandwidth": 50000000000 "max-reservable-bandwidth": 50000000000
} }
} }
} }
--example-4
9. Compatibility with Other ALTO Extensions 9. Compatibility with Other ALTO Extensions
9.1. Compatibility with Legacy ALTO Clients/Servers 9.1. Compatibility with Legacy ALTO Clients/Servers
The multipart Filtered Cost Map resource and the multipart Endpoint The multipart filtered cost map resource and the multipart Endpoint
Cost Service resource has no backward compatibility issue with legacy Cost Service resource have no backward-compatibility issues with
ALTO clients and servers. Although these two types of resources legacy ALTO clients and servers. Although these two types of
reuse the media types defined in the base ALTO protocol for the resources reuse the media types defined in the base ALTO Protocol for
accept input parameters, they have different media types for the "Accept" input parameters, they have different media types for
responses. If the ALTO server provides these two types of resources, responses. If the ALTO server provides these two types of resources
but the ALTO client does not support them, the ALTO client will but the ALTO client does not support them, the ALTO client will
ignore the resources without incurring any incompatibility problem. ignore the resources without incurring any incompatibility problems.
9.2. Compatibility with Multi-Cost Extension 9.2. Compatibility with Multi-Cost Extension
The extension defined in this document is compatible with the multi- The extension defined in this document is compatible with the multi-
cost extension [RFC8189]. Such a resource has a media type of either cost extension [RFC8189]. Such a resource has a media type of either
"multipart/related; type=application/alto-costmap+json" or "multipart/related; type=application/alto-costmap+json" or
"multipart/related; type=application/alto-endpointcost+json". Its "multipart/related; type=application/alto-endpointcost+json". Its
"cost-constraints" field must either be "false" or not present and "cost-constraints" field must be either "false" or not present, and
the Path Vector cost type must be present in the "cost-type-names" the Path Vector cost type must be present in the "cost-type-names"
capability field but must not be present in the "testable-cost-type- capability field but must not be present in the "testable-cost-type-
names" field, as specified in Section 7.2.4 and Section 7.3.4. names" field, as specified in Sections 7.2.4 and 7.3.4.
9.3. Compatibility with Incremental Update 9.3. Compatibility with Incremental Update Extension
This extension is compatible with the incremental update extension This extension is compatible with the incremental update extension
[RFC8895]. ALTO clients and servers MUST follow the specifications [RFC8895]. ALTO clients and servers MUST follow the specifications
given in Sections 5.2 and 6.7.3 of [RFC8895] to support incremental given in Sections 5.2 and 6.7.3 of [RFC8895] to support incremental
updates for a Path Vector resource. updates for a Path Vector resource.
9.4. Compatibility with Cost Calendar 9.4. Compatibility with Cost Calendar Extension
The extension specified in this document is compatible with the Cost The extension specified in this document is compatible with the Cost
Calendar extension [RFC8896]. When used together with the Cost Calendar extension [RFC8896]. When used together with the Cost
Calendar extension, the cost value between a source and a destination Calendar extension, the cost value between a source and a destination
is an array of Path Vectors, where the k-th Path Vector refers to the is an array of Path Vectors, where the k-th Path Vector refers to the
abstract network paths traversed in the k-th time interval by traffic abstract network paths traversed in the k-th time interval by traffic
from the source to the destination. from the source to the destination.
When used with time-varying properties, e.g., maximum reservable When used with time-varying properties, e.g., maximum reservable
bandwidth, a property of a single ANE may also have different values bandwidth, a property of a single ANE may also have different values
in different time intervals. In this case, if such an ANE has in different time intervals. In this case, if such an ANE has
different property values in two time intervals, it MUST be treated different property values in two time intervals, it MUST be treated
as two different ANEs, i.e., with different entity identifiers. as two different ANEs, i.e., with different entity identifiers.
However, if it has the same property values in two time intervals, it However, if it has the same property values in two time intervals, it
MAY use the same identifier. MAY use the same identifier.
This rule allows the Path Vector extension to represent both changes This rule allows the Path Vector extension to represent both changes
of ANEs and changes of the ANEs' properties in a uniform way. The of ANEs and changes of the ANEs' properties in a uniform way. The
Path Vector part is calendared in a compatible way, and the Property Path Vector part is calendared in a compatible way, and the property
Map part is not affected by the calendar extension. map part is not affected by the Cost Calendar extension.
The two extensions combined together can provide the historical The two extensions combined together can provide the historical
network correlation information for a set of source and destination network correlation information for a set of source and destination
pairs. A network broker or client may use this information to derive pairs. A network broker or client may use this information to derive
other resource requirements such as Time-Block-Maximum Bandwidth, other resource requirements such as Time-Block-Maximum Bandwidth,
Bandwidth-Sliding-Window, and Time-Bandwidth-Product (TBP) (See Bandwidth-Sliding-Window, and Time-Bandwidth-Product (TBP) (see
[SENSE] for details). [SENSE] for details).
10. General Discussions 10. General Discussion
10.1. Constraint Tests for General Cost Types 10.1. Constraint Tests for General Cost Types
The constraint test is a simple approach to query the data. It The constraint test is a simple approach for querying the data. It
allows users to filter the query result by specifying some boolean allows users to filter query results by specifying some boolean
tests. This approach is already used in the ALTO protocol. tests. This approach is already used in the ALTO Protocol. ALTO
[RFC7285] and [RFC8189] allow ALTO clients to specify the clients are permitted to specify either the "constraints" test
"constraints" and "or-constraints" tests to better filter the result. [RFC7285] [RFC8189] or the "or-constraints" test [RFC8189] to better
filter the results.
However, the current syntax can only be used to test scalar cost However, the current syntax can only be used to test scalar cost
types, and cannot easily express constraints on complex cost types, types and cannot easily express constraints on complex cost types,
e.g., the Path Vector cost type defined in this document. e.g., the Path Vector cost type defined in this document.
In practice, developing a bespoke language for general-purpose In practice, developing a bespoke language for general-purpose
boolean tests can be a complex undertaking, and it is conceivable boolean tests can be a complex undertaking, and it is conceivable
that there are some existing implementations already (the authors that such implementations already exist (the authors have not done an
have not done an exhaustive search to determine whether there are exhaustive search to determine whether such implementations exist).
such implementations). One avenue to develop such a language may be One avenue for developing such a language may be to explore extending
to explore extending current query languages like XQuery [XQuery] or current query languages like XQuery [XQuery] or JSONiq [JSONiq] and
JSONiq [JSONiq] and integrating these with ALTO. integrating these with ALTO.
Filtering the Path Vector results or developing a more sophisticated Filtering the Path Vector results or developing a more sophisticated
filtering mechanism is beyond the scope of this document. filtering mechanism is beyond the scope of this document.
10.2. General Multi-Resource Query 10.2. General Multi-Resource Query
Querying multiple ALTO information resources continuously is a Querying multiple ALTO information resources continuously is a
general requirement. Enabling such a capability, however, must general requirement. Enabling such a capability, however, must
address general issues like efficiency and consistency. The address general issues like efficiency and consistency. The
incremental update extension [RFC8895] supports submitting multiple incremental update extension [RFC8895] supports submitting multiple
queries in a single request, and allows flexible control over the queries in a single request and allows flexible control over the
queries. However, it does not cover the case introduced in this queries. However, it does not cover the case introduced in this
document where multiple resources are needed for a single request. document where multiple resources are needed for a single request.
This extension gives an example of using a multipart message to The extension specified in this document gives an example of using a
encode the responses from two specific ALTO information resources: a multipart message to encode the responses from two specific ALTO
Filtered Cost Map or an Endpoint Cost Service, and a Property Map. By information resources: a filtered cost map or an Endpoint Cost
packing multiple resources in a single response, the implication is Service, and a property map. By packing multiple resources in a
that servers may proactively push related information resources to single response, the implication is that servers may proactively push
clients. related information resources to clients.
Thus, it is worth looking into the direction of extending the SSE Thus, it is worth looking into extending the SSE mechanism as used in
mechanism as used in the incremental update extension [RFC8895], or the incremental update extension [RFC8895]; or upgrading to HTTP/2
upgrading to HTTP/2 [I-D.ietf-httpbis-http2bis] and HTTP/3 [RFC9113] and HTTP/3 [RFC9114], which provides the ability to
[I-D.ietf-quic-http], which provides the ability to multiplex queries multiplex queries and to allow servers to proactively send related
and to allow servers proactively send related information resources. information resources.
Defining a general multi-resource query mechanism is out of the scope Defining a general multi-resource query mechanism is out of scope for
of this document. this document.
11. Security Considerations 11. Security Considerations
This document is an extension of the base ALTO protocol, so the This document is an extension of the base ALTO Protocol, so the
Security Considerations [RFC7285] of the base ALTO protocol fully security considerations provided for the base ALTO Protocol [RFC7285]
apply when this extension is provided by an ALTO server. fully apply when this extension is provided by an ALTO server.
The Path Vector extension requires additional scrutiny on three The Path Vector extension requires additional scrutiny of three
security considerations discussed in the base protocol: security considerations discussed in the base protocol:
confidentiality of ALTO information (Section 15.3 of [RFC7285]), confidentiality of ALTO information (Section 15.3 of [RFC7285]),
potential undesirable guidance from authenticated ALTO information potential undesirable guidance from authenticated ALTO information
(Section 15.2 of [RFC7285]), and availability of ALTO service (Section 15.2 of [RFC7285]), and availability of ALTO services
(Section 15.5 of [RFC7285]). (Section 15.5 of [RFC7285]).
For confidentiality of ALTO information, a network operator should be For confidentiality of ALTO information, a network operator should be
aware that this extension may introduce a new risk: the Path Vector aware that this extension may introduce a new risk: the Path Vector
information, when used together with sensitive ANE properties such as information, when used together with sensitive ANE properties such as
capacities of bottleneck links, may make network attacks easier. For capacities of bottleneck links, may make network attacks easier. For
example, as the Path Vector information may reveal more fine-grained example, as the Path Vector information may reveal more fine-grained
internal network structures than the base protocol, an attacker may internal network structures than the base protocol, an attacker may
identify the bottleneck link and start a distributed denial-of- identify the bottleneck link or links and start a distributed denial-
service (DDoS) attack involving minimal flows to conduct the in- of-service (DDoS) attack involving minimal flows, triggering in-
network congestion. Given the potential risk of leaking sensitive network congestion. Given the potential risk of leaking sensitive
information, the Path Vector extension is mainly applicable in information, the Path Vector extension is mainly applicable in
scenarios where 1) the ANE structures and ANE properties do not scenarios where 1) the ANE structures and ANE properties do not
impose security risks to the ALTO service provider, e.g., not impose security risks on the ALTO service provider (e.g., they do not
carrying sensitive information, or 2) the ALTO server and client have carry sensitive information) or 2) the ALTO server and client have
established a reliable trust relationship, for example, operated in established a reliable trust relationship (e.g., they operate in the
the same administrative domain, or managed by business partners with same administrative domain or are managed by business partners with
legal contracts. legal contracts).
Three risk types are identified in Section 15.3.1 of [RFC7285]:
(1) excess disclosure of the ALTO service provider's data to an
unauthorized ALTO client,
(2) disclosure of the ALTO service provider's data (e.g., network
topology information or endpoint addresses) to an unauthorized
third party, and
(3) excess retrieval of the ALTO service provider's data by
collaborating ALTO clients.
Three risk types are identified in Section 15.3.1 of [RFC7285]: (1)
Excess disclosure of the ALTO service provider's data to an
unauthorized ALTO client; (2) Disclosure of the ALTO service
provider's data (e.g., network topology information or endpoint
addresses) to an unauthorized third party; and (3) Excess retrieval
of the ALTO service provider's data by collaborating ALTO clients.
To mitigate these risks, an ALTO server MUST follow the guidelines in To mitigate these risks, an ALTO server MUST follow the guidelines in
Section 15.3.2 of [RFC7285]. Furthermore, an ALTO server MUST follow Section 15.3.2 of [RFC7285]. Furthermore, an ALTO server MUST follow
the following additional protections strategies for risk types (1) the following additional protections strategies for risk types (1)
and (3). and (3).
For risk type (1), an ALTO server MUST use the authentication methods For risk type (1), an ALTO server MUST use the authentication methods
specified in Section 15.3.2 of [RFC7285] to authenticate the identify specified in Section 15.3.2 of [RFC7285] to authenticate the identity
of an ALTO client, and apply access control techniques to restrict of an ALTO client and apply access control techniques to restrict the
unprivileged ALTO clients from retrieving sensitive Path Vector retrieval of sensitive Path Vector information by unprivileged ALTO
information. For settings where the ALTO server and client are not clients. For settings where the ALTO server and client are not in
in the same trust domain, the ALTO server should reach agreements the same trust domain, the ALTO server should reach agreements with
with the ALTO client on protecting the confidentiality before the ALTO client regarding protection of confidentiality before
granting the access to Path Vector service with sensitive granting access to Path Vector services with sensitive information.
information. Such agreements may include legal contracts or Digital Such agreements may include legal contracts or Digital Rights
Right Management (DRM) techniques. Otherwise, the ALTO server MUST Management (DRM) techniques. Otherwise, the ALTO server MUST NOT
NOT offer the Path Vector service carrying sensitive information to offer Path Vector services that carry sensitive information to the
the clients unless the potential risks are fully assessed and clients, unless the potential risks are fully assessed and mitigated.
mitigated.
For risk type (3), an ALTO service provider must be aware that For risk type (3), an ALTO service provider must be aware that
persistent ANEs may be used as "landmarks" in collaborative persistent ANEs may be used as "landmarks" in collaborative
inferences. Thus, they should only be used when exposing public inferences. Thus, they should only be used when exposing public
service access points (e.g., API gateways, CDNi) and/or when the service access points (e.g., API gateways, CDN Interconnections) and/
granularity is coarse-grained (e.g., when an ANE represents an AS, a or when the granularity is coarse grained (e.g., when an ANE
data center or a WAN). Otherwise, an ALTO server MUST use dynamic represents an AS, a data center, or a WAN). Otherwise, an ALTO
mappings from ephemeral ANE names to underlying physical entities. server MUST use dynamic mappings from ephemeral ANE names to
Specifically, for the same physical entity, an ALTO server SHOULD underlying physical entities. Specifically, for the same physical
assign a different ephemeral ANE name when the entity appears in the entity, an ALTO server SHOULD assign a different ephemeral ANE name
responses to different clients or even for different request from the when the entity appears in the responses to different clients or even
same client. A RECOMMENDED assignment strategy is to generate ANE for different requests from the same client. A RECOMMENDED
names from random numbers. assignment strategy is to generate ANE names from random numbers.
Further, to protect the network topology from graph reconstruction Further, to protect the network topology from graph reconstruction
(e.g., through isomorphic graph identification [BONDY]), the ALTO (e.g., through isomorphic graph identification [BONDY]), the ALTO
server SHOULD consider protection mechanisms to reduce information server SHOULD consider protection mechanisms to reduce information
exposure or obfuscate the real information. When doing so, the ALTO exposure or obfuscate the real information. When doing so, the ALTO
server must be aware that information reduction/obfuscation may lead server must be aware that information reduction/obfuscation may lead
to potential Undesirable Guidance from Authenticated ALTO Information to a potential risk of undesirable guidance from authenticated ALTO
risk (Section 15.2 of [RFC7285]). information (Section 15.2 of [RFC7285]).
Thus, implementations of ALTO servers involving reduction or Thus, implementations of ALTO servers involving reduction or
obfuscation of the Path Vector information SHOULD consider reduction/ obfuscation of the Path Vector information SHOULD consider reduction/
obfuscation mechanisms that can preserve the integrity of ALTO obfuscation mechanisms that can preserve the integrity of ALTO
information, for example, by using minimal feasible region information -- for example, by using minimal feasible region
compression algorithms [NOVA] or obfuscation protocols compression algorithms [NOVA] or obfuscation protocols [RESA]
[RESA][MERCATOR]. However, these obfuscation methods are [MERCATOR]. However, these obfuscation methods are experimental, and
experimental and their practical applicability of these methods to their practical applicability to the generic capability provided by
the generic capability provided by this extension is not fully this extension has not been fully assessed. The ALTO server MUST
assessed. The ALTO server MUST carefully verify that the deployment carefully verify that the deployment scenario satisfies the security
scenario satisfies the security assumptions of these methods before assumptions of these methods before applying them to protect Path
applying them to protect Path Vector services with sensitive network Vector services with sensitive network information.
information.
For availability of ALTO service, an ALTO server should be cognizant For availability of ALTO services, an ALTO server should be cognizant
that using Path Vector extension might have a new risk: frequent that using a Path Vector extension might introduce a new risk:
requesting for Path Vectors might consume intolerable amounts of the frequent requests for Path Vectors might consume intolerable amounts
server-side computation and storage, which can break the ALTO server. of server-side computation and storage. This behavior can break the
For example, if an ALTO server implementation dynamically computes ALTO server. For example, if an ALTO server implementation
the Path Vectors for each request, the service providing Path Vectors dynamically computes the Path Vectors for each request, the service
may become an entry point for denial-of-service attacks on the that provides the Path Vectors may become an entry point for denial-
availability of an ALTO server. of-service attacks on the availability of an ALTO server.
To mitigate this risk, an ALTO server may consider using To mitigate this risk, an ALTO server may consider using such
optimizations such as precomputation-and-projection mechanisms optimizations as precomputation-and-projection mechanisms [MERCATOR]
[MERCATOR] to reduce the overhead for processing each query. Also, to reduce the overhead for processing each query. An ALTO server may
an ALTO server may also protect itself from malicious clients by also protect itself from malicious clients by monitoring client
monitoring the behaviors of clients and stopping serving clients with behavior and stopping service to clients that exhibit suspicious
suspicious behaviors (e.g., sending requests at a high frequency). behavior (e.g., sending requests at a high frequency).
The ALTO service providers must be aware that providing incremental The ALTO service providers must be aware that providing incremental
updates of the "max-reservable-bandwidth" may provide information updates of "max-reservable-bandwidth" may provide information about
about other consumers of the network. For example, a change of the other consumers of the network. For example, a change in value may
value may indicate one or more reservations has been made or changed. indicate that one or more reservations have been made or changed. To
To mitigate this risk, an ALTO server can batch the updates and/or mitigate this risk, an ALTO server can batch the updates and/or add a
add a random delay before publishing the updates. random delay before publishing the updates.
12. IANA Considerations 12. IANA Considerations
12.1. ALTO Cost Metric Registry 12.1. "ALTO Cost Metrics" Registry
This document registers a new entry to the ALTO Cost Metric Registry, This document registers a new entry in the "ALTO Cost Metrics"
as instructed by Section 14.2 of [RFC7285]. The new entry is as registry, per Section 14.2 of [RFC7285]. The new entry is as shown
shown below in Table 1. below in Table 1.
+============+====================+=========================+ +============+====================+===========+
| Identifier | Intended Semantics | Security Considerations | | Identifier | Intended Semantics | Reference |
+============+====================+=========================+ +============+====================+===========+
| ane-path | See Section 6.5.1 | See Section 11 | | ane-path | See Section 6.5.1 | RFC 9275 |
+------------+--------------------+-------------------------+ +------------+--------------------+-----------+
Table 1: ALTO Cost Metric Registry Table 1: "ALTO Cost Metrics" Registry
12.2. ALTO Cost Mode Registry 12.2. "ALTO Cost Modes" Registry
This document registers a new entry to the ALTO Cost Mode Registry, This document registers a new entry in the "ALTO Cost Modes"
as instructed by Section 4 of [I-D.bw-alto-cost-mode]. The new entry registry, per Section 5 of [RFC9274]. The new entry is as shown
is as shown below in Table 2. below in Table 2.
+============+====================+ +============+=========================+=============+===========+
| Identifier | Intended Semantics | | Identifier | Description | Intended | Reference |
+============+====================+ | | | Semantics | |
| array | See Section 6.5.2 | +============+=========================+=============+===========+
+------------+--------------------+ | array | Indicates that the cost | See Section | RFC 9275 |
| | value is a JSON array | 6.5.2 | |
+------------+-------------------------+-------------+-----------+
Table 2: ALTO Cost Mode Registry Table 2: "ALTO Cost Modes" Registry
12.3. ALTO Entity Domain Type Registry 12.3. "ALTO Entity Domain Types" Registry
This document registers a new entry to the ALTO Domain Entity Type This document registers a new entry in the "ALTO Entity Domain Types"
Registry, as instructed by Section 12.2 of registry, per Section 12.3 of [RFC9240]. The new entry is as shown
[I-D.ietf-alto-unified-props-new]. The new entry is as shown below below in Table 3.
in Table 3.
+============+============+=============+===================+=======+ +============+============+=============+===================+=======+
| Identifier |Entity | Hierarchy & |Media Type of |Mapping| | Identifier |Entity |Hierarchy and| Media Type of |Mapping|
| |Identifier | Inheritance |Defining Resoucrce |to ALTO| | |Identifier |Inheritance | Defining Resource |to ALTO|
| |Encoding | | |Address| | |Encoding | | |Address|
| | | | |Type | | | | | |Type |
+============+============+=============+===================+=======+ +============+============+=============+===================+=======+
| ane |See Section | None |application/alto- |false | | ane |See Section |None | application/alto- |false |
| |6.2.2 | |propmap+json | | | |6.2.2 | | propmap+json | |
+------------+------------+-------------+-------------------+-------+ +------------+------------+-------------+-------------------+-------+
Table 3: ALTO Entity Domain Type Registry Table 3: "ALTO Entity Domain Types" Registry
Identifier: See Section 6.2.1. Identifier: See Section 6.2.1.
Entity Identifier Encoding: See Section 6.2.2. Entity Identifier Encoding: See Section 6.2.2.
Hierarchy: None Hierarchy: None
Inheritance: None Inheritance: None
Media Type of Defining Resource: See Section 6.2.4. Media Type of Defining Resource: See Section 6.2.4.
Mapping to ALTO Address Type: This entity type does not map to ALTO Mapping to ALTO Address Type: This entity type does not map to an
address type. ALTO address type.
Security Considerations: In some usage scenarios, ANE addresses Security Considerations: In some usage scenarios, ANE addresses
carried in ALTO Protocol messages may reveal information about an carried in ALTO Protocol messages may reveal information about an
ALTO client or an ALTO service provider. Applications and ALTO ALTO client or an ALTO service provider. If a naming schema is
service providers using addresses of ANEs will be made aware of used to generate ANE names, either used privately or standardized
how (or if) the addressing scheme relates to private information by a future extension, how (or if) the naming schema relates to
and network proximity, in further iterations of this document. private information and network proximity must be explained to
ALTO implementers and service providers.
12.4. ALTO Entity Property Type Registry 12.4. "ALTO Entity Property Types" Registry
Two initial entries "max-reservable-bandwidth" and "persistent- Two initial entries -- "max-reservable-bandwidth" and "persistent-
entity-id" are registered to the ALTO Domain "ane" in the "ALTO entity-id" -- are registered for the ALTO domain "ane" in the "ALTO
Entity Property Type Registry", as instructed by Section 12.3 of Entity Property Types" registry, per Section 12.4 of [RFC9240]. The
[I-D.ietf-alto-unified-props-new]. The two new entries are shown two new entries are shown below in Table 4, and their details can be
below in Table 4 and their details can be found in Section 12.4.1 and found in Sections 12.4.1 and 12.4.2 of this document.
Section 12.4.2.
+==========================+====================+===================+ +==========================+====================+===================+
| Identifier | Intended | Media Type of | | Identifier | Intended | Media Type of |
| | Semantics | Defining Resource | | | Semantics | Defining Resource |
+==========================+====================+===================+ +==========================+====================+===================+
| max-reservable-bandwidth | See Section | application/alto- | | max-reservable-bandwidth | See Section | application/alto- |
| | 6.4.1 | propmap+json | | | 6.4.1 | propmap+json |
+--------------------------+--------------------+-------------------+ +--------------------------+--------------------+-------------------+
| persistent-entity-id | See Section | application/alto- | | persistent-entity-id | See Section | application/alto- |
| | 6.4.2 | propmap+json | | | 6.4.2 | propmap+json |
+--------------------------+--------------------+-------------------+ +--------------------------+--------------------+-------------------+
Table 4: Initial Entries for ane Domain in the ALTO Entity Table 4: Initial Entries for the "ane" Domain in the "ALTO Entity
Property Types Registry Property Types" Registry
12.4.1. New ANE Property Type: Maximum Reservable Bandwidth 12.4.1. New ANE Property Type: Maximum Reservable Bandwidth
Identifier: "max-reservable-bandwidth" Identifier: "max-reservable-bandwidth"
Intended Semantics: See Section 6.4.1. Intended Semantics: See Section 6.4.1.
Media Type of Defining Resource: application/alto-propmap+json Media Type of Defining Resource: application/alto-propmap+json
Security Considerations: This property is essential for applications Security Considerations: To make better choices regarding bandwidth
such as large-scale data transfers or overlay network reservation, this property is essential for applications such as
interconnection to make better choice of bandwidth reservation. large-scale data transfers or an overlay network interconnection.
It may reveal the bandwidth usage of the underlying network and It may reveal the bandwidth usage of the underlying network and
can potentially be leveraged to reduce the cost of conducting can potentially be leveraged to reduce the cost of conducting
denial-of-service attacks. Thus, the ALTO server MUST consider denial-of-service attacks. Thus, the ALTO server MUST consider
protection mechanisms including only providing the information to such protection mechanisms as providing the information to
authorized clients, and information reduction and obfuscation as authorized clients only and applying information reduction and
introduced in Section 11. obfuscation as discussed in Section 11.
12.4.2. New ANE Property Type: Persistent Entity ID 12.4.2. New ANE Property Type: Persistent Entity ID
Identifier: "persistent-entity-id" Identifier: "persistent-entity-id"
Intended Semantics: See Section 6.4.2. Intended Semantics: See Section 6.4.2.
Media Type of Defining Resource: application/alto-propmap+json Media Type of Defining Resource: application/alto-propmap+json
Security Considerations: This property is useful when an ALTO server Security Considerations: This property is useful when an ALTO server
wants to selectively expose certain service points whose detailed wants to selectively expose certain service points whose detailed
properties can be further queried by applications. The entity IDs properties can be further queried by applications. As mentioned
may consider sensitive information about the underlying network, in Section 12.3.2 of [RFC9240], the entity IDs may reveal
and an ALTO server should follow the security considerations in sensitive information about the underlying network. An ALTO
Section 11 of [I-D.ietf-alto-unified-props-new]. server should follow the security considerations provided in
Section 11 of [RFC9240].
13. References 13. References
13.1. Normative References 13.1. Normative References
[I-D.bw-alto-cost-mode]
Boucadair, M. and Q. Wu, "A Cost Mode Registry for the
Application-Layer Traffic Optimization (ALTO) Protocol",
Work in Progress, Internet-Draft, draft-bw-alto-cost-mode-
01, 4 March 2022, <https://datatracker.ietf.org/doc/html/
draft-bw-alto-cost-mode-01>.
[I-D.ietf-alto-unified-props-new]
Roome, W., Randriamasy, S., Yang, Y. R., Zhang, J. J., and
K. Gao, "An ALTO Extension: Entity Property Maps", Work in
Progress, Internet-Draft, draft-ietf-alto-unified-props-
new-24, 28 February 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-alto-
unified-props-new-24>.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046, Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996, DOI 10.17487/RFC2046, November 1996,
<https://www.rfc-editor.org/rfc/rfc2046>. <https://www.rfc-editor.org/info/rfc2046>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2387] Levinson, E., "The MIME Multipart/Related Content-type", [RFC2387] Levinson, E., "The MIME Multipart/Related Content-type",
RFC 2387, DOI 10.17487/RFC2387, August 1998, RFC 2387, DOI 10.17487/RFC2387, August 1998,
<https://www.rfc-editor.org/rfc/rfc2387>. <https://www.rfc-editor.org/info/rfc2387>.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, [RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008, DOI 10.17487/RFC5322, October 2008,
<https://www.rfc-editor.org/rfc/rfc5322>. <https://www.rfc-editor.org/info/rfc5322>.
[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S., [RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy, Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol", "Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014, RFC 7285, DOI 10.17487/RFC7285, September 2014,
<https://www.rfc-editor.org/rfc/rfc7285>. <https://www.rfc-editor.org/info/rfc7285>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8189] Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost [RFC8189] Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost
Application-Layer Traffic Optimization (ALTO)", RFC 8189, Application-Layer Traffic Optimization (ALTO)", RFC 8189,
DOI 10.17487/RFC8189, October 2017, DOI 10.17487/RFC8189, October 2017,
<https://www.rfc-editor.org/rfc/rfc8189>. <https://www.rfc-editor.org/info/rfc8189>.
[RFC8895] Roome, W. and Y. Yang, "Application-Layer Traffic [RFC8895] Roome, W. and Y. Yang, "Application-Layer Traffic
Optimization (ALTO) Incremental Updates Using Server-Sent Optimization (ALTO) Incremental Updates Using Server-Sent
Events (SSE)", RFC 8895, DOI 10.17487/RFC8895, November Events (SSE)", RFC 8895, DOI 10.17487/RFC8895, November
2020, <https://www.rfc-editor.org/rfc/rfc8895>. 2020, <https://www.rfc-editor.org/info/rfc8895>.
[RFC8896] Randriamasy, S., Yang, R., Wu, Q., Deng, L., and N. [RFC8896] Randriamasy, S., Yang, R., Wu, Q., Deng, L., and N.
Schwan, "Application-Layer Traffic Optimization (ALTO) Schwan, "Application-Layer Traffic Optimization (ALTO)
Cost Calendar", RFC 8896, DOI 10.17487/RFC8896, November Cost Calendar", RFC 8896, DOI 10.17487/RFC8896, November
2020, <https://www.rfc-editor.org/rfc/rfc8896>. 2020, <https://www.rfc-editor.org/info/rfc8896>.
[RFC9240] Roome, W., Randriamasy, S., Yang, Y., Zhang, J., and K.
Gao, "An Extension for Application-Layer Traffic
Optimization (ALTO): Entity Property Maps", RFC 9240,
DOI 10.17487/RFC9240, July 2022,
<https://www.rfc-editor.org/info/rfc9240>.
[RFC9274] Boucadair, M. and Q. Wu, "A Cost Mode Registry for the
Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 9274, DOI 10.17487/RFC9274, July 2022,
<https://www.rfc-editor.org/info/rfc9274>.
13.2. Informative References 13.2. Informative References
[BONDY] Bondy, J.A. and R.L. Hemminger, "Graph reconstruction—a [ALTO-PERF-METRICS]
survey", Journal of Graph Theory, Volume 1, Issue 3, pp Wu, Q., Yang, Y., Lee, Y., Dhody, D., Randriamasy, S., and
227-268 , 1977, <https://doi.org/10.1002/jgt.3190010306>. L. Contreras, "ALTO Performance Cost Metrics", Work in
Progress, Internet-Draft, draft-ietf-alto-performance-
metrics-28, 21 March 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-alto-
performance-metrics-28>.
[BONDY] Bondy, J.A. and R.L. Hemminger, "Graph reconstruction--a
survey", Journal of Graph Theory, Volume 1, Issue 3, pp.
227-268, DOI 10.1002/jgt.3190010306, 1977,
<https://onlinelibrary.wiley.com/doi/10.1002/
jgt.3190010306>.
[BOXOPT] Xiang, Q., Yu, H., Aspnes, J., Le, F., Kong, L., and Y.R. [BOXOPT] Xiang, Q., Yu, H., Aspnes, J., Le, F., Kong, L., and Y.R.
Yang, "Optimizing in the dark: Learning an optimal Yang, "Optimizing in the Dark: Learning an Optimal
solution through a simple request interface", Proceedings Solution through a Simple Request Interface", Proceedings
of the AAAI Conference on Artificial Intelligence 33, of the AAAI Conference on Artificial Intelligence 33,
1674-1681 , 2019, 1674-1681, DOI 10.1609/aaai.v33i01.33011674, July 2019,
<https://doi.org/10.1609/aaai.v33i01.33011674>. <https://ojs.aaai.org//index.php/AAAI/article/view/3984>.
[CLARINET] Viswanathan, R., Ananthanarayanan, G., and A. Akella, [CLARINET] Viswanathan, R., Ananthanarayanan, G., and A. Akella,
"CLARINET: WAN-Aware Optimization for Analytics Queries", "CLARINET: WAN-aware optimization for analytics queries",
In 12th USENIX Symposium on Operating Systems Design and Proceedings of the 12th USENIX conference on Operating
Implementation (OSDI 16), USENIX Association, Savannah, Systems Design and Implementation (OSDI'16), Savannah, GA,
GA, 435-450 , 2016, pp. 435-450, November 2016,
<https://dl.acm.org/doi/abs/10.5555/3026877.3026911>. <https://dl.acm.org/doi/abs/10.5555/3026877.3026911>.
[G2] Ros-Giralt, J., Bohara, A., Yellamraju, S., Langston, [G2] Ros-Giralt, J., Bohara, A., Yellamraju, S., Langston,
M.H., Lethin, R., Jiang, Y., Tassiulas, L., Li, J., Tan, M.H., Lethin, R., Jiang, Y., Tassiulas, L., Li, J., Tan,
Y., and M. Veeraraghavan, "On the Bottleneck Structure of Y., and M. Veeraraghavan, "On the Bottleneck Structure of
Congestion-Controlled Networks", Proceedings of the ACM on Congestion-Controlled Networks", Proceedings of the ACM on
Measurement and Analysis of Computing Systems, Volume 3, Measurement and Analysis of Computing Systems, Volume 3,
Issue 3, pp 1-31 , 2019, Issue 3, pp. 1-31, DOI 10.1145/3366707, December 2019,
<https://dl.acm.org/doi/10.1145/3366707>. <https://dl.acm.org/doi/10.1145/3366707>.
[HUG] Chowdhury, M., Liu, Z., Ghodsi, A., and I. Stoica, "HUG: [HUG] Chowdhury, M., Liu, Z., Ghodsi, A., and I. Stoica, "HUG:
Multi-Resource Fairness for Correlated and Elastic multi-resource fairness for correlated and elastic
Demands", 13th USENIX Symposium on Networked Systems demands", Proceedings of the 13th USENIX Conference on
Design and Implementation (NSDI 16) (Santa Clara, CA, Networked Systems Design and Implementation (NSDI'16),
2016), 407-424. , 2016, Santa Clara, CA, pp. 407-424, March 2016,
<https://dl.acm.org/doi/10.5555/2930611.2930638>. <https://dl.acm.org/doi/10.5555/2930611.2930638>.
[I-D.ietf-alto-performance-metrics] [INTENT-BASED-NETWORKING]
Wu, Q., Yang, Y. R., Lee, Y., Dhody, D., Randriamasy, S., Clemm, A., Ciavaglia, L., Granville, L. Z., and J.
and L. M. C. Murillo, "ALTO Performance Cost Metrics", Tantsura, "Intent-Based Networking - Concepts and
Work in Progress, Internet-Draft, draft-ietf-alto- Definitions", Work in Progress, Internet-Draft, draft-
performance-metrics-26, 2 March 2022, irtf-nmrg-ibn-concepts-definitions-09, 24 March 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-alto- <https://datatracker.ietf.org/doc/html/draft-irtf-nmrg-
performance-metrics-26>. ibn-concepts-definitions-09>.
[I-D.ietf-httpbis-http2bis]
Thomson, M. and C. Benfield, "HTTP/2", Work in Progress,
Internet-Draft, draft-ietf-httpbis-http2bis-07, 24 January
2022, <https://datatracker.ietf.org/doc/html/draft-ietf-
httpbis-http2bis-07>.
[I-D.ietf-quic-http]
Bishop, M., "Hypertext Transfer Protocol Version 3
(HTTP/3)", Work in Progress, Internet-Draft, draft-ietf-
quic-http-34, 2 February 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-quic-
http-34>.
[JSONiq] "The JSON Query language", 2020, [JSONiq] JSONiq, "The JSON Query Language", 2022,
<https://www.jsoniq.org/>. <https://www.jsoniq.org/>.
[MERCATOR] Xiang, Q., Zhang, J., Wang, X., Liu, Y., Guok, C., Le, F., [MERCATOR] Xiang, Q., Zhang, J., Wang, X., Liu, Y., Guok, C., Le, F.,
MacAuley, J., Newman, H., and Y.R. Yang, "Toward Fine- MacAuley, J., Newman, H., and Y.R. Yang, "Toward Fine-
Grained, Privacy-Preserving, Efficient Multi-Domain Grained, Privacy-Preserving, Efficient Multi-Domain
Network Resource Discovery", IEEE/ACM IEEE Journal on Network Resource Discovery", IEEE/ACM, IEEE Journal on
Selected Areas of Communication 37(8): 1924-1940, 2019, Selected Areas in Communications, Volume 37, Issue 8, pp.
<https://doi.org/10.1109/JSAC.2019.2927073>. 1924-1940, DOI 10.1109/JSAC.2019.2927073, August 2019,
<https://ieeexplore.ieee.org/document/8756056>.
[MOWIE] Zhang, Y., Li, G., Xiong, C., Lei, Y., Huang, W., Han, Y., [MOWIE] Zhang, Y., Li, G., Xiong, C., Lei, Y., Huang, W., Han, Y.,
Walid, A., Yang, Y.R., and Z. Zhang, "MoWIE: Toward Walid, A., Yang, Y.R., and Z. Zhang, "MoWIE: Toward
Systematic, Adaptive Network Information Exposure as an Systematic, Adaptive Network Information Exposure as an
Enabling Technique for Cloud-Based Applications over 5G Enabling Technique for Cloud-Based Applications over 5G
and Beyond", In Proceedings of the Workshop on Network and Beyond", Proceedings of the Workshop on Network
Application Integration/CoDesign, ACM, Virtual Event USA, Application Integration/CoDesign (NAI '20), ACM, Virtual
20-27. , 2020, <https://doi.org/10.1145/3405672.3409489>. Event USA, pp. 20-27, DOI 10.1145/3405672.3409489, August
2020, <https://dl.acm.org/doi/10.1145/3405672.3409489>.
[NOVA] Gao, K., Xiang, Q., Wang, X., Yang, Y.R., and J. Bi, "An [NOVA] Gao, K., Xiang, Q., Wang, X., Yang, Y.R., and J. Bi, "An
objective-driven on-demand network abstraction for Objective-Driven On-Demand Network Abstraction for
adaptive applications", IEEE/ACM Transactions on Adaptive Applications", IEEE/ACM Transactions on
Networking (TON) Vol 27, no. 2 (2019): 805-818., 2019, Networking (TON) Vol. 27, Issue 2, pp. 805-818,
<https://doi.org/10.1109/IWQoS.2017.7969117>. DOI 10.1109/TNET.2019.2899905, April 2019,
<https://doi.org/10.1109/TNET.2019.2899905>.
[RESA] Xiang, Q., Zhang, J., Wang, X., Liu, Y., Guok, C., Le, F., [RESA] Xiang, Q., Zhang, J., Wang, X., Liu, Y., Guok, C., Le, F.,
MacAuley, J., Newman, H., and Y.R. Yang, "Fine-grained, MacAuley, J., Newman, H., and Y.R. Yang, "Fine-Grained,
multi-domain network resource abstraction as a fundamental Multi-Domain Network Resource Abstraction as a Fundamental
primitive to enable high-performance, collaborative data Primitive to Enable High-Performance, Collaborative Data
sciences", Proceedings of the Super Computing 2018, Sciences", SC18: International Conference for High
5:1-5:13 , 2019, <https://doi.org/10.1109/SC.2018.00008>. Performance Computing, Networking, Storage and Analysis,
pp. 58-70, DOI 10.1109/SC.2018.00008, November 2018,
<https://ieeexplore.ieee.org/document/8665783>.
[RFC2216] Shenker, S. and J. Wroclawski, "Network Element Service [RFC2216] Shenker, S. and J. Wroclawski, "Network Element Service
Specification Template", RFC 2216, DOI 10.17487/RFC2216, Specification Template", RFC 2216, DOI 10.17487/RFC2216,
September 1997, <https://www.rfc-editor.org/rfc/rfc2216>. September 1997, <https://www.rfc-editor.org/info/rfc2216>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006, DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/rfc/rfc4271>. <https://www.rfc-editor.org/info/rfc4271>.
[SENSE] "Software Defined Networking (SDN) for End-to-End [RFC9113] Thomson, M., Ed. and C. Benfield, Ed., "HTTP/2", RFC 9113,
DOI 10.17487/RFC9113, June 2022,
<https://www.rfc-editor.org/info/rfc9113>.
[RFC9114] Bishop, M., Ed., "HTTP/3", RFC 9114, DOI 10.17487/RFC9114,
June 2022, <https://www.rfc-editor.org/info/rfc9114>.
[SENSE] ESnet, "Software Defined Networking (SDN) for End-to-End
Networked Science at the Exascale", 2019, Networked Science at the Exascale", 2019,
<https://www.es.net/network-r-and-d/sense/>. <https://www.es.net/network-r-and-d/sense/>.
[SEREDGE] Contreras, L., Baliosian, J., Martı́nez-Julia, P., and J. [SEREDGE] Contreras, L., Baliosian, J., Martínez-Julia, P., and J.
Serrat, "Computing at the Edge: But, what Edge?", In Serrat, "Computing at the Edge: But, what Edge?",
proceedings of the NOMS 2020 - 2020 IEEE/IFIP Network Proceedings of NOMS 2020 - 2020 IEEE/IFIP Network
Operations and Management Symposium. pp. 1-9. , 2020, Operations and Management Symposium, pp. 1-9,
<https://doi.org/10.1109/NOMS47738.2020.9110342>. DOI 10.1109/NOMS47738.2020.9110342, April 2020,
<https://ieeexplore.ieee.org/document/9110342>.
[SWAN] Hong, C., Kandula, S., Mahajan, R., Zhang, M., Gill, V., [SWAN] Hong, C., Kandula, S., Mahajan, R., Zhang, M., Gill, V.,
Nanduri, M., and R. Wattenhofer, "Achieving High Nanduri, M., and R. Wattenhofer, "Achieving high
Utilization with Software-driven WAN", In Proceedings of utilization with software-driven WAN", Proceedings of the
the ACM SIGCOMM 2013 Conference on SIGCOMM (SIGCOMM '13), ACM SIGCOMM 2013 conference on SIGCOMM (SIGCOMM '13), New
ACM, New York, NY, USA, 15-26. , 2013, York, NY, pp. 15-26, DOI 10.1145/2486001.2486012, August
<http://doi.acm.org/10.1145/2486001.2486012>. 2013, <https://dl.acm.org/doi/10.1145/2486001.2486012>.
[UNICORN] Xiang, Q., Chen, S., Gao, K., Newman, H., Taylor, I., [UNICORN] Xiang, Q., Wang, T., Zhang, J., Newman, H., Yang, Y.R.,
Zhang, J., and Y.R. Yang, "Unicorn: Unified Resource and Y. Liu, "Unicorn: Unified resource orchestration for
Orchestration for Multi-Domain, Geo-Distributed Data multi-domain, geo-distributed data analytics", Future
Analytics", 2017 IEEE SmartWorld, Ubiquitous Intelligence Generation Computer Systems, Volume 93, pp. 188-197,
Computing, Advanced Trusted Computed, Scalable Computing DOI 10.1016/j.future.2018.09.048, April 2019,
Communications, Cloud Big Data Computing, Internet of <https://www.sciencedirect.com/science/article/abs/pii/
People and Smart City Innovation S0167739X18302413?via%3Dihub>.
(SmartWorld/SCALCOM/UIC/ATC/CBDCom/IOP/SCI) (Aug. 2017),
1-6. , 2017,
<https://doi.org/10.1016/j.future.2018.09.048>.
[XQuery] "XQuery 3.1: An XML Query Language", 2017, [XQuery] Robie, J., Ed., Dyck, M., Ed., and J. Spiegel, Ed.,
<https://www.w3.org/TR/xquery-31/>. "XQuery 3.1: An XML Query Language", W3C Recommendation,
March 2017, <https://www.w3.org/TR/xquery-31/>.
Appendix A. Acknowledgments Acknowledgments
The authors would like to thank discussions with Andreas Voellmy, The authors would like to thank Andreas Voellmy, Erran Li, Haibin
Erran Li, Haibin Song, Haizhou Du, Jiayuan Hu, Qiao Xiang, Tianyuan Song, Haizhou Du, Jiayuan Hu, Tianyuan Liu, Xiao Shi, Xin Wang, and
Liu, Xiao Shi, Xin Wang, and Yan Luo. The authors thank Greg Yan Luo for fruitful discussions. The authors thank Greg Bernstein,
Bernstein, Dawn Chen, Wendy Roome, and Michael Scharf for their Dawn Chen, Wendy Roome, and Michael Scharf for their contributions to
contributions to earlier drafts. earlier draft versions of this document.
The authors would also like to thank Tim Chown, Luis Contreras, Roman The authors would also like to thank Tim Chown, Luis Contreras, Roman
Danyliw, Benjamin Kaduk, Erik Kline, Suresh Krishnan, Murray Danyliw, Benjamin Kaduk, Erik Kline, Suresh Krishnan, Murray
Kucherawy, Warren Kumari, Danny Lachos, Francesca Palombini, Eric Kucherawy, Warren Kumari, Danny Lachos, Francesca Palombini, Éric
Vyncke, Samuel Weiler, and Qiao Xiang whose feedback and suggestions Vyncke, Samuel Weiler, and Qiao Xiang, whose feedback and suggestions
are invaluable to improve the practicability and conciseness of this were invaluable for improving the practicability and conciseness of
document, and Mohamed Boucadair, Martin Duke, Vijay Gurbani, Jan this document; and Mohamed Boucadair, Martin Duke, Vijay Gurbani, Jan
Seedorf, and Qin Wu who provide great support and guidance. Seedorf, and Qin Wu, who provided great support and guidance.
Appendix B. Revision Logs (To be removed before publication)
B.1. Changes since -20
Reivision -21
* changes the normative requirement on protecting confidentiality of
PV information with softer language
B.2. Changes since -19
Revision -20
* changes the IANA registry information
* adopts the comments from IESG reviews
B.3. Changes since -18
Revision -19
* adds detailed examples for use cases
* clarify terms with ambiguous meanings
B.4. Changes since -17
Revision -18
* changes the specification for content-id to conform to [RFC2387]
and [RFC5322]
* adds IPv6 examples
B.5. Changes since -16
Revision -17
* adds items for media type of defining resources in IANA
considerations
B.6. Changes since -15
Revision -16
* resolves the compatibility with the Multi-Cost extension (RFC
8189)
* adds media types of defining resources for ANE property types (for
IANA registration)
B.7. Changes since -14
Revision -15
* fixes the IDNits warnings,
* fixes grammar issues,
* addresses the comments in the AD review.
B.8. Changes since -13
Revision -14
* addresses the comments in the chair review,
* fixes most issues raised by IDNits.
B.9. Changes since -12
Revision -13
* changes the abstract based on the chairs' reviews
* integrates Richard's responds to WGLC reviews
B.10. Changes since -11
Revision -12
* clarifies the definition of ANEs in a similar way as how Network
Elements is defined in [RFC2216]
* restructures several paragraphs that are not clear (Sec 3, Path
Vector bullet, Sec 4.2, Sec 5.1.3, Sec 6.2.4, Sec 6.4.2, Sec 9.3)
* uses "ALTO Entity Domain Type Registry"
B.11. Changes since -10
Revision -11
* replaces "part" with "components" in the abstract;
* identifies additional requirements (AR) derived from the flow
scheduling example, and introduces how the extension addresses the
additional requirements
* fixes the inconsistent use of "start" parameter in multipart
responses;
* specifies explicitly how to handle "cost-constraints";
* uses the latest IANA registration mechanism defined in
[I-D.ietf-alto-unified-props-new];
* renames "persistent-entities" to "persistent-entity-id";
* makes "application/alto-propmap+json" as the media type of
defining resources for the "ane" domain;
* updates the examples;
* adds the discussion on ephemeral and persistent ANEs.
B.12. Changes since -09
Revision -10
* revises the introduction which
- extends the scope where the PV extension can be applied beyond
the "path correlation" information
* brings back the capacity region use case to better illustrate the
problem
* revises the overview to explain and defend the concepts and
decision choices
* fixes inconsistent terms, typos
B.13. Changes since -08
This revision
* fixes a few spelling errors
* emphasizes that abstract network elements can be generated on
demand in both introduction and motivating use cases
B.14. Changes Since Version -06
* We emphasize the importance of the path vector extension in two
aspects:
1. It expands the problem space that can be solved by ALTO, from
preferences of network paths to correlations of network paths.
2. It is motivated by new usage scenarios from both application's
and network's perspectives.
* More use cases are included, in addition to the original capacity
region use case.
* We add more discussions to fully explore the design space of the
path vector extension and justify our design decisions, including
the concept of abstract network element, cost type (reverted to
-05), newer capabilities and the multipart message.
* Fix the incremental update process to be compatible with SSE -16
draft, which uses client-id instead of resource-id to demultiplex
updates.
* Register an additional ANE property (i.e., persistent-entities) to
cover all use cases mentioned in the draft.
Authors' Addresses Authors' Addresses
Kai Gao Kai Gao
Sichuan University Sichuan University
No.24 South Section 1, Yihuan Road No.24 South Section 1, Yihuan Road
Chengdu Chengdu
610000 610000
China China
Email: kaigao@scu.edu.cn Email: kaigao@scu.edu.cn
Young Lee Young Lee
Samsung Samsung
South Korea Republic of Korea
Email: younglee.tx@gmail.com Email: younglee.tx@gmail.com
Sabine Randriamasy Sabine Randriamasy
Nokia Bell Labs Nokia Bell Labs
Route de Villejust Route de Villejust
91460 Nozay 91460 Nozay
France France
Email: sabine.randriamasy@nokia-bell-labs.com Email: sabine.randriamasy@nokia-bell-labs.com
Yang Richard Yang Yang Richard Yang
Yale University Yale University
51 Prospect Street 51 Prospect Street
New Haven, CT New Haven, CT 06511
United States of America United States of America
Email: yry@cs.yale.edu Email: yry@cs.yale.edu
Jingxuan Jensen Zhang Jingxuan Jensen Zhang
Tongji University Tongji University
4800 Caoan Road 4800 Caoan Road
Shanghai Shanghai
201804 201804
China China
Email: jingxuan.n.zhang@gmail.com Email: jingxuan.n.zhang@gmail.com
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