Network Working Group
Internet Engineering Task Force (IETF) D. Dhody
Internet-Draft
Request for Comments: 9168 Huawei Technologies
Intended status:
Category: Standards Track A. Farrel
Expires: May 3, 2021
ISSN: 2070-1721 Old Dog Consulting
Z. Li
Huawei Technologies
October 30, 2020
PCEP
January 2022
Path Computation Element Communication Protocol (PCEP) Extension for
Flow Specification
draft-ietf-pce-pcep-flowspec-12
Abstract
The Path Computation Element (PCE) is a functional component capable
of selecting paths through a traffic engineering (TE) network. These
paths may be supplied in response to requests for computation, computation or may
be unsolicited requests issued by the PCE to network elements. Both
approaches use the PCE Communication Protocol (PCEP) to convey the
details of the computed path.
Traffic flows may be categorized and described using "Flow
Specifications". RFC XXXX 8955 defines the Flow Specification and
describes how Flow Specification Components components are used to describe
traffic flows. RFC XXXX 8955 also defines how Flow Specifications may be
distributed in BGP to allow specific traffic flows to be associated
with routes.
This document specifies a set of extensions to PCEP to support
dissemination of Flow Specifications. This allows a PCE to indicate
what traffic should be placed on each path that it is aware of.
The extensions defined in this document include the creation, update,
and withdrawal of Flow Specifications via PCEP, PCEP and can be applied to
tunnels initiated by the PCE or to tunnels where control is delegated
to the PCE by the PCC. Path Computation Client (PCC). Furthermore, a PCC
requesting a new path can include Flow Specifications in the request
to indicate the purpose of the tunnel allowing the PCE to factor this
into the path computation.
RFC Editor Note: Please replace XXXX in the Abstract with the RFC
number assigned to draft-ietf-idr-rfc5575bis when it is published.
Please remove this note.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of six months RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 3, 2021.
https://www.rfc-editor.org/info/rfc9168.
Copyright Notice
Copyright (c) 2020 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified Revised BSD License text as described in Section 4.e of the
Trust Legal Provisions and are provided without warranty as described
in the Simplified Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Procedures for PCE Use of Flow Specifications . . . . . . . . 6
3.1. Context for PCE Use of Flow Specifications . . . . . . . 6
3.2. Elements of the Procedure . . . . . . . . . . . . . . . . . . 7
3.2.1. Capability Advertisement . . . . . . . . . . . . . . 7
3.2.1.1. PCEP Open Message
3.2.1.2. IGP PCE Capabilities Advertisement
3.2.2. Dissemination Procedures . . . . . . . . . . . . . . 8
3.2.3. Flow Specification Synchronization . . . . . . . . . 9
4. PCE FlowSpec Capability TLV . . . . . . . . . . . . . . . . . 10
5. PCEP FLOWSPEC Object . . . . . . . . . . . . . . . . . . . . 10
6. Flow Filter TLV and L2 Flow Filter TLV . . . . . . . . . . . 13
7. Flow Specification TLVs . . . . . . . . . . . . . . . . . . . 13
7.1. L2 Flow Specification TLVs . . . . . . . . . . . . . . . 17
8. Detailed Procedures . . . . . . . . . . . . . . . . . . . . . 18
8.1. Default Behavior and Backward Compatibility . . . . . . . 18
8.2. Composite Flow Specifications . . . . . . . . . . . . . . 19
8.3. Modifying Flow Specifications . . . . . . . . . . . . . . 19
8.4. Multiple Flow Specifications . . . . . . . . . . . . . . 19
8.5. Adding and Removing Flow Specifications . . . . . . . . . 20
8.6. VPN Identifiers . . . . . . . . . . . . . . . . . . . . . 20
8.7. Priorities and Overlapping Flow Specifications . . . . . 20
9. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 21
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
10.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 24
10.1.1. PCEP FLOWSPEC Object Flag Field . . . . . . . . . . 24
10.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 25
10.3. Flow Specification TLV Type Indicators . . . . . . . . . 25
10.4. L2 Flow Specification TLV Type Indicators . . . . . . . 26
10.5. PCEP Error Codes . . . . . . . . . . . . . . . . . . . . 27
10.6.
10.5. PCE Capability Flag . . . . . . . . . . . . . . . . . . 27
11. Implementation Status . . . . . . . . . . . . . . . . . . . . 27
12. Security Considerations . . . . . . . . . . . . . . . . . . . 28
13.
12. Manageability Considerations . . . . . . . . . . . . . . . . 29
13.1.
12.1. Management of Multiple Flow Specifications . . . . . . . 29
13.2.
12.2. Control of Function through Configuration and Policy . . 30
13.3.
12.3. Information and Data Models . . . . . . . . . . . . . . 30
13.4.
12.4. Liveness Detection and Monitoring . . . . . . . . . . . 31
13.5.
12.5. Verifying Correct Operation . . . . . . . . . . . . . . 31
13.6.
12.6. Requirements on for Other Protocols and Functional Components . . . . . . . . . . . . . . . . . . . . . . . 31
13.7.
12.7. Impact on Network Operation . . . . . . . . . . . . . . 31
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 31
15.
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 31
15.1.
13.1. Normative References . . . . . . . . . . . . . . . . . . 32
15.2.
13.2. Informative References . . . . . . . . . . . . . . . . . 33
Appendix A.
Acknowledgements
Contributors . . . . . . . . . . . . . . . . . . . . 35
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36
1. Introduction
[RFC4655] defines the Path Computation Element (PCE), a functional
component capable of computing paths for use in traffic engineering
networks. PCE was originally conceived for use in Multiprotocol
Label Switching (MPLS) for Traffic Engineering traffic engineering (TE) networks to
derive the routes of Label Switched Paths (LSPs). However, the scope
of PCE was quickly extended to make it applicable to networks
controlled by Generalized MPLS
(GMPLS)-controlled networks, (GMPLS), and more recent work has
brought other traffic engineering technologies and planning
applications into scope (for example, Segment Routing (SR)
[RFC8664]).
[RFC5440] describes the Path Computation Element PCE Communication Protocol (PCEP). PCEP
defines the communication between a Path Computation Client (PCC) and
a PCE, or between PCE and PCE, enabling computation of the path for
MPLS-TE LSPs.
Stateful PCE [RFC8231] specifies a set of extensions to PCEP to
enable control of TE-LSPs by a PCE that retains state about the LSPs
provisioned in the network (a stateful PCE). [RFC8281] describes the
setup, maintenance, and teardown of LSPs initiated by a stateful PCE
without the need for local configuration on the PCC, thus allowing
for a dynamic network that is centrally controlled. [RFC8283]
introduces the architecture for PCE as a central controller and
describes how PCE can be viewed as a component that performs
computation to place 'flows' "flows" within the network and decide how these
flows are routed.
The description of traffic flows by the combination of multiple Flow
Specification Components components and their dissemination as traffic flow
specifications (Flow Specifications) is described for BGP in
[I-D.ietf-idr-rfc5575bis].
[RFC8955]. In BGP, a Flow Specification is comprised of traffic
filtering rules and is associated with actions to perform on the
packets that match the Flow Specification. The BGP routers that
receive a Flow Specification can classify received packets according
to the traffic filtering rules and can direct packets based on the
associated actions.
When a PCE is used to initiate tunnels (such as TE-LSPs or SR paths)
using PCEP, it is important that the head end of the tunnels
understands what traffic to place on each tunnel. The data flows
intended for a tunnel can be described using Flow Specification
Components.
components. When PCEP is in use for tunnel initiation initiation, it makes
sense for that same protocol to be used to distribute the Flow
Specification Components components that describe what data is to flow on those
tunnels.
This document specifies a set of extensions to PCEP to support
dissemination of Flow Specification Components. components. We term the
description of a traffic flow using Flow Specification Components components as
a "Flow Specification". This term is conceptually the same as the
term used in [I-D.ietf-idr-rfc5575bis], [RFC8955]; however, no mechanism is provided to
distribute an action associated with the Flow Specification because
there is only one action that is applicable in the PCEP context (that
is, directing the matching traffic to the identified LSP).
The extensions defined in this document include the creation, update,
and withdrawal of Flow Specifications via PCEP, PCEP and can be applied to
tunnels initiated by the PCE or to tunnels where control is delegated
to the PCE by the PCC. Furthermore, a PCC requesting a new path can
include Flow Specifications in the request to indicate the purpose of
the tunnel allowing the PCE to factor this into the path computation.
Flow Specifications are carried in TLVs within a new object called
the FLOWSPEC object defined in this document. The flow filtering
rules indicated by the Flow Specifications are mainly defined by BGP
Flow Specifications.
Note that PCEP-installed Flow Specifications are intended to be
installed only at the head-end head end of the LSP to which they direct
traffic. It is acceptable (and potentially desirable) that other
routers in the network have Flow Specifications installed that match
the same traffic, traffic but direct it onto different routes or to different
LSPs. Those other Flow Specifications may be installed using the
PCEP extensions defined in this document, may be distributed using BGP per [I-D.ietf-idr-rfc5575bis],
[RFC8955], or may be configured using manual operations. Since this
document is about PCEP-installed Flow Specifications, those other
Flow Specifications at other routers are out of scope. In this
context, however, it is worth noting that changes to the wider
routing system (such as the distribution and installation of BGP Flow
Specifications, or fluctuations in the IGP link state database) might
mean that traffic matching the PCEP Flow Specification never reaches
the head end of the LSP at which the PCEP Flow Specification has been
installed. This may or may not be desirable according to the
operator's traffic engineering and routing
policies, policies and is
particularly applicable at LSPs that do not have their head ends at
the ingress-edge ingress edge of the network, but it is not an effect that this
document seeks to address.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document uses the following terms defined in [RFC5440]: PCC,
PCE, and PCEP Peer.
The following term from [I-D.ietf-idr-rfc5575bis] [RFC8955] is used frequently throughout this
document:
| A Flow Specification is an n-tuple consisting of several matching
| criteria that can be applied to IP traffic. A given IP packet is
| said to match the defined Flow Specification if it matches all the
| specified criteria.
[I-D.ietf-idr-rfc5575bis]
[RFC8955] also states that "A "[a] given Flow Specification may be
associated with a set of attributes," attributes" and that, that "...attributes can be
used to encode a set of predetermined actions." However, in the
context of this document, no action is explicitly specified as
associated with the Flow Specification since the action
"forward of forwarding
all matching traffic onto the associated path" path is implicit.
How an implementation decides how to filter traffic that matches a Flow
Specification does not form part of this specification, but a flag is
provided to indicate whether the sender of a PCEP message that
includes a Flow Specification intends it to be installed as a Longest
Prefix Match (LPM) route or as a Flow Specification policy.
This document uses the terms "stateful PCE" and "active PCE" as
advocated in [RFC7399].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Procedures for PCE Use of Flow Specifications
3.1. Context for PCE Use of Flow Specifications
In the PCE architecture architecture, there are five steps in the setup and use of
LSPs:
1. Decide which LSPs to set up. The decision may be made by a user,
by a PCC, or by the PCE. There can be a number of triggers for
this
this, including user intervention and dynamic response to changes
in traffic demands.
2. Decide what properties to assign to an LSP. This can include
bandwidth reservations, priorities, and DSCP the Differentiated
Services Code Point (DSCP) (i.e., MPLS Traffic Class field).
This function is also determined by user configuration or in
response to predicted or observed traffic demands.
3. Decide what traffic to put on the LSP. This is effectively
determining which traffic flows to assign to which LSPs, and LSPs;
practically, this is closely linked to the first two decisions
listed above.
4. Cause the LSP to be set up and modified to have the right
characteristics. This will usually involve the PCE advising or
instructing the PCC at the head end of the LSP, and the PCC will
then signal the LSP across the network.
5. Tell the head end of the LSP what traffic to put on the LSP.
This may happen after or at the same time as the LSP is set up.
This step is the subject of this document.
3.2. Elements of the Procedure
There are three elements of in the procedure:
o
1. A PCE and a PCC must be able to indicate whether or not they
support the use of Flow Specifications.
o
2. A PCE or PCC must be able to include Flow Specifications in PCEP
messages with a clear understanding of the applicability of those
Flow Specifications in each case. This includes whether the use
of such information is mandatory, constrained, or optional, optional and
how overlapping Flow Specifications will be resolved.
o
3. Flow Specification information/state must be synchronized between
PCEP peers so that, on recovery, the peers have the same
understanding of which Flow Specifications apply just as is
required in the case of stateful PCE and LSP delegation (see
Section 5.6 of [RFC8231]).
The following subsections describe these points.
3.2.1. Capability Advertisement
As with most PCEP capability advertisements, the ability to support
Flow Specifications can be indicated in the PCEP OPEN Open message or in
IGP PCE capability advertisements.
3.2.1.1. PCEP OPEN Open Message
During PCEP session establishment, a PCC or PCE that supports the
procedures described in this document announces this fact by
including the "PCE PCE FlowSpec Capability" Capability TLV (described in Section 4) in
the OPEN Object object carried in the PCEP Open message.
The presence of the PCE FlowSpec Capability TLV in the OPEN Object object in
a PCE's OPEN Open message indicates that the PCE can distribute FlowSpecs
to PCCs and can receive FlowSpecs in messages from PCCs.
The presence of the PCE FlowSpec Capability TLV in the OPEN Object object in
a PCC's OPEN Open message indicates that the PCC supports the FlowSpec
functionality described in this document.
If either one of a pair of PCEP peers does not include the PCE
FlowSpec Capability TLV in the OPEN Object object in its OPEN Open message, then
the other peer MUST NOT include a FLOWSPEC object in any PCEP message
sent to the peer. If a FLOWSPEC object is received when support has
not been indicated, the receiver will respond with a PCErr message
reporting the objects containing the FlowSpec as described in
[RFC5440]: that is, it will use 'Unknown Object' "Unknown Object" if it does not
support this specification, specification and 'Not "Not supported object' object" if it supports
this specification but has not chosen to support FLOWSPEC objects on
this PCEP session.
3.2.1.2. IGP PCE Capabilities Advertisement
The ability to advertise support for PCEP and PCE features in IGP
advertisements is provided for OSPF in [RFC5088] and for IS-IS in
[RFC5089]. The mechanism uses the PCE Discovery TLV TLV, which has a PCE-
CAP-FLAGS
PCE-CAP-FLAGS sub-TLV containing bit-flags bit flags, each of which indicates
support for a different feature.
This document defines a new PCE-CAP-FLAGS sub-TLV bit, the FlowSpec
Capable flag (bit number TBD1). 16). Setting the bit indicates that an
advertising PCE supports the procedures defined in this document.
Note that while PCE FlowSpec Capability capability may be advertised during
discovery, PCEP speakers that wish to use Flow Specification in PCEP
MUST negotiate PCE FlowSpec Capability capability during PCEP session setup, as
specified in Section 3.2.1.1. A PCC MAY initiate PCE FlowSpec
Capability
capability negotiation at PCEP session setup even if it did not
receive any IGP PCE capability advertisement, and a PCEP peer that
advertised support for FlowSpec in the IGP is not obliged to support
these procedures on any given PCEP session.
3.2.2. Dissemination Procedures
This section describes the procedures to support Flow Specifications
in PCEP messages.
The primary purpose of distributing Flow Specification information is
to allow a PCE to indicate to a PCC what traffic it should place on a
path (such as an LSP or an SR path). This means that the Flow
Specification may be included in:
o
* PCInitiate messages so that an active PCE can indicate the traffic
to place on a path at the time that the PCE instantiates the path.
o
* PCUpd messages so that an active PCE can indicate or change the
traffic to place on a path that has already been set up.
o
* PCRpt messages so that a PCC can report the traffic that the PCC
will place on the path.
o
* PCReq messages so that a PCC can indicate what traffic it plans to
place on a path at the time when it requests that the PCE to perform a
computation in case that information aids the PCE in its work.
o
* PCRep messages so that a PCE that has been asked to compute a path
can suggest which traffic could be placed on a path that a PCC may
be about to set up.
o
* PCErr messages so that issues related to paths and the traffic
they carry can be reported to the PCE by the PCC, PCC and so that problems with
other PCEP messages that carry Flow Specifications can be
reported.
To carry Flow Specifications in PCEP messages, this document defines
a new PCEP object called the PCEP "PCEP FLOWSPEC object. object". The object is
OPTIONAL in the messages described above and MAY appear more than
once in each message.
To describe a traffic flow, the PCEP FLOWSPEC object carries one of
the following combinations of TLVs:
o zero or one Flow Filter TLV
o one L2 Flow Filter TLV
o both a Flow
Filter TLV and an L2 Flow Filter TLV TLV.
The inclusion of multiple PCEP FLOWSPEC objects allows multiple
traffic flows to be placed on a single path.
Once a PCE and PCC have established that they can both support the
use of Flow Specifications in PCEP messages, such information may be
exchanged at any time for new or existing paths.
The application and prioritization of Flow Specifications is are
described in Section 8.7.
As per [RFC8231], any attributes of the path received from a PCE are
subject to the PCC's local policy. This holds good true for the Flow
Specifications as well.
3.2.3. Flow Specification Synchronization
The Flow Specifications are carried along with the LSP State state
information as per [RFC8231] [RFC8231], making the Flow Specifications part of
the LSP database (LSP-DB). Thus, the synchronization of the Flow
Specification information is done as part of LSP-DB synchronization.
This may be achieved using normal state synchronization procedures as
described in [RFC8231] or enhanced state synchronization procedures
as defined in [RFC8232].
The approach selected will be implementation and deployment specific
and will depend on issues such as how the databases are constructed
and what level of synchronization support is needed.
4. PCE FlowSpec Capability TLV
The PCE-FLOWSPEC-CAPABILITY TLV is an optional TLV that can be
carried in the OPEN Object object [RFC5440] to exchange the PCE FlowSpec
capabilities of the PCEP speakers.
The format of the PCE-FLOWSPEC-CAPABILITY TLV follows the format of
all PCEP TLVs as defined in [RFC5440] and is shown in Figure 1.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD2 Type=51 | Length=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value=0 | Padding |
+---------------------------------------------------------------+
Figure 1: PCE-FLOWSPEC-CAPABILITY TLV format Format
The type of the PCE-FLOWSPEC-CAPABILITY TLV is TBD2 51, and it has a fixed
length of 2 octets. The Value field MUST be set to 0 and MUST be
ignored on receipt. The two bytes of padding MUST be set to zero and
ignored on receipt.
The inclusion of this TLV in an OPEN object indicates that the sender
can perform FlowSpec handling as defined in this document.
5. PCEP FLOWSPEC Object
The PCEP FLOWSPEC object defined in this document is compliant with
the PCEP object format defined in [RFC5440]. It is OPTIONAL in the
PCReq, PCRep, PCErr, PCInitiate, PCRpt, and PCUpd messages and MAY be
present zero, one, or more times. Each instance of the object
specifies a separate traffic flow.
The PCEP FLOWSPEC object carries MAY carry a FlowSpec filter rule encoded in
a
TLV (a Flow Filter TLV, a single L2 Flow Filter TLV, or both) TLV as defined in Section 6). 6.
The FLOWSPEC Object-Class is TBD3 43 (to be assigned by IANA).
The FLOWSPEC Object-Type is 1.
The format of the body of the PCEP FLOWSPEC object is shown in
Figure 2 2.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FS-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AFI | Reserved | Flags |L|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: PCEP FLOWSPEC Object Body Format
FS-ID (32-bits): (32 bits): A PCEP-specific identifier for the FlowSpec
information. A PCE or PCC creates an FS-ID for each FlowSpec that
it originates, and the value is unique within the scope of that
PCE or PCC and is constant for the lifetime of a PCEP session.
All subsequent PCEP messages can identify the FlowSpec using the
FS-ID. The values 0 and 0xFFFFFFFF are reserved and MUST NOT be
used. Note that [I-D.gont-numeric-ids-sec-considerations] [NUMERIC-IDS-SEC] gives advice on assigning
transient numeric identifiers such as the FS-ID so as to
minimise minimize
security risks.
AFI (16-bits): (16 bits): Address Family Identifier as used in BGP [RFC4760]
(AFI=1 for IPv4 or VPNv4, AFI=2 for IPv6 and VPNv6 as per as per
[I-D.ietf-idr-flow-spec-v6]).
[RFC8956]).
Reserved (8-bits): (8 bits): MUST be set to zero on transmission and ignored
on receipt.
Flags (8-bits): (8 bits): Two flags are currently assigned - assigned:
R bit: The Remove bit is set when a PCEP FLOWSPEC object is
included in a PCEP message to indicate removal of the Flow
Specification from the associated tunnel. If the bit is clear,
the Flow Specification is being added or modified.
L bit: The Longest Prefix Match (LPM) bit is set to indicate that
the Flow Specification is to be installed as a route subject to
longest prefix match
LPM forwarding. If the bit is clear, the Flow Specification
described by the Flow Filter TLV (see Section 6) is to be
installed as a Flow Specification. If the bit is set, only
Flow Specifications that describe IPv4 or IPv6 destinations are
meaningful in the Flow Filter TLV TLV, and others are ignored. If
the L is set and the receiver does not support the use of Flow
Specifications that are present in the Flow Filter TLV for the
installation of a route subject to longest prefix match LPM forwarding, then the
PCEP peer MUST respond with a PCErr message with error-type TBD8 Error-Type 30
(FlowSpec Error) and error-value Error-value 5 (Unsupported LPM Route).
Unassigned bits MUST be set to zero on transmission and ignored on
receipt.
If the PCEP speaker receives a message with the R bit set in the
FLOWSPEC object and the Flow Specification identified with a an FS-ID
does not exist, it MUST generate a PCErr with Error-type TBD8 Error-Type 30 (FlowSpec
Error), error-value
Error) and Error-value 4 (Unknown FlowSpec).
If the PCEP speaker does not understand or support the AFI in the
FLOWSPEC message, the PCEP peer MUST respond with a PCErr message
with error-type TBD8 Error-Type 30 (FlowSpec Error), error-value Error) and Error-value 2 (Malformed
FlowSpec).
The following TLVs can be used in the FLOWSPEC object:
o
Speaker Entity Identifier TLV: As specified in [RFC8232], the
SPEAKER-ENTITY-ID TLV encodes a unique identifier for the node
that does not change during the lifetime of the PCEP speaker.
This is used to uniquely identify the FlowSpec originator and thus
is used in conjunction with the FS-ID to uniquely identify the
FlowSpec information. This TLV MUST be included. If the TLV is
missing, the PCEP peer MUST respond with a PCErr message with error-type
TBD8
Error-Type 30 (FlowSpec Error), error-value Error) and Error-value 2 (Malformed
FlowSpec). If more than one instance of this TLV is present, the
first MUST be
processed processed, and subsequence subsequent instances MUST be ignored.
o
Flow Filter TLV (variable): One TLV MAY be included. The Flow
Filter TLV is OPTIONAL when the R bit is set.
o L2 Flow Filter TLV (variable): One TLV MAY be included.
The L2
Flow Filter TLV is OPTIONAL when the R bit is set.
At least one Flow Filter TLV or one L2 Flow Filter TLV MUST be present when the R bit is clear. If both TLVs are the
TLV is missing when the R bit is clear, the PCEP peer MUST respond
with a PCErr message with
error-type TBD8 Error-Type 30 (FlowSpec Error) and error-value Error-
value 2 (Malformed FlowSpec). A Flow Filter TLV and a L2 Flow Filter TLV MAY both be
present when filtering is
Filtering based on both L3 and the L2 fields. fields is out of scope of this document.
6. Flow Filter TLV and L2 Flow Filter TLV
Two
One new PCEP TLVs are TLV is defined to convey Flow Specification filtering
rules that specify what traffic is carried on a path. The TLVs
follow TLV
follows the format of all PCEP TLVs as defined in [RFC5440]. The
Type field values come from the codepoint code point space for PCEP TLVs and
has the value TBD4 for Flow Filter TLV and TBD9 52 for L2 Flow Filter TLV.
The Value fields field of the TLVs contain TLV contains one or more sub-TLVs (the Flow
Specification TLVs or L2 Flow Specification TLVs) as defined in Section 7, and they represent the
complete definition of a Flow Specification for traffic to be placed
on the tunnel. This tunnel is indicated by the PCEP message in which
the PCEP FLOWSPEC object is carried. The set of Flow Specification
TLVs and L2 Flow Filter TLVs in a single instance of a Flow Filter TLV are is combined to
indicate the specific Flow Specification. Note that the PCEP
FLOWSPEC object can include just one Flow Filter TLV, just one L2 Flow Filter TLV, or
one of each TLV.
Further Flow Specifications can be included in a PCEP message by
including additional FLOWSPEC objects.
In the future, there may be a desire to add support for L2 Flow
Specifications (such as described in [BGP-L2VPN]).
7. Flow Specification TLVs
The Flow Filter TLV carries one or more Flow Specification TLVs. The
Flow Specification TLV follows the format of all PCEP TLVs as defined
in [RFC5440]. However, the Type values are selected from a separate
IANA registry (see Section 10.3) rather than from the common PCEP TLV
registry.
Type values are chosen so that there can be commonality with Flow
Specifications defined for use with BGP [I-D.ietf-idr-rfc5575bis] and
[I-D.ietf-idr-flow-spec-v6]. [RFC8955] [RFC8956]. This is
possible because the BGP Flow Spec encoding uses a single octet to
encode the type where as type, whereas PCEP uses two 2 octets. Thus Thus, the space of
values for the Type field is partitioned as shown in Figure 3. Table 1.
+===========+=======================================+
| Range |
---------------+---------------------------------------------------
0 .. 255 Description |
+===========+=======================================+
| 0-255 | Per BGP Flow Spec registry defined by | [I-D.ietf-idr-rfc5575bis]
| | [RFC8955] and [RFC8956]. |
| | |
| [I-D.ietf-idr-flow-spec-v6]. | Not to be allocated in this registry. |
256 .. 65535
+-----------+---------------------------------------+
| 256-65535 | New PCEP Flow Specifications |
| | allocated according
| to the registry |
| | defined in this document.
Figure 3: |
+-----------+---------------------------------------+
Table 1: Flow Specification TLV Type Ranges
[I-D.ietf-idr-rfc5575bis]
[RFC8955] is the reference for the registry "Flow Spec Component Types"
registry and defines the allocations it contains.
[I-D.ietf-idr-flow-spec-v6] [RFC8956]
requested for another registry the creation of the "Flow Spec IPv6 Component Types" and requested
registry, as well as its initial allocations in it. allocations. If the AFI (in the
FLOWSPEC object) is set to IPv4, the range 0..255 is as per "Flow
Spec Component Types" [I-D.ietf-idr-rfc5575bis]; [RFC8955]; if the AFI is set to IPv6, the range
0..255 is as per "Flow Spec IPv6 Component Types" [I-D.ietf-idr-flow-spec-v6]. [RFC8956].
The content of the Value field in each TLV is specific to the type/
AFI and describes the parameters of the Flow Specification. The
definition of the format of many of these Value fields is inherited
from BGP specifications. Specifically, the inheritance is from
[I-D.ietf-idr-rfc5575bis]
[RFC8955] and [I-D.ietf-idr-flow-spec-v6], [RFC8956], but it may also be inherited from future BGP
specifications.
When multiple Flow Specification TLVs are present in a single Flow
Filter TLV TLV, they are combined to produce a more detailed
specification of a flow. For examples and rules about how this is
achieved, see
[I-D.ietf-idr-rfc5575bis]. [RFC8955]. As described in [I-D.ietf-idr-rfc5575bis] [RFC8955], where it says "A
given component type MAY (exactly once) be present in the Flow Specification,"
Specification", a Flow Filter TLV MUST NOT contain more than one Flow
Specification TLV of the same type: an implementation that receives a
PCEP message with a Flow Flter Filter TLV that contains more than one Flow
Specification TLV of the same type MUST respond with a PCErr message
with error-type TBD8 Error-Type 30 (FlowSpec Error), error-value Error) and Error-value 2 (Malformed
FlowSpec) and MUST NOT install the Flow Specification.
An implementation that receives a PCEP message carrying a Flow
Specification TLV with a type value that it does not recognize or
does not
support MUST respond with a PCErr message with error-type
TBD8 Error-Type 30
(FlowSpec Error), error-value Error) and Error-value 1 (Unsupported FlowSpec) and MUST
NOT install the Flow Specification.
When used in other protocols (such as BGP), these Flow Specifications
are also associated with actions to indicate how traffic matching the
Flow Specification should be treated. In PCEP, however, the only
action is to associate the traffic with a tunnel and to forward
matching traffic onto that path, so no encoding of an action is
needed.
Section 8.7 describes how overlapping Flow Specifications are
prioritized and handled.
All Flow Specification TLVs with Types in the range 0 to 255 have
Values
values defined for use in BGP (for example, in
[I-D.ietf-idr-rfc5575bis] [RFC8955] and [I-D.ietf-idr-flow-spec-v6])
[RFC8956]) and are set using the BGP encoding, encoding but without the type
octet (the relevant information is in the Type field of the TLV).
The Value field is padded with trailing zeros to achieve 4-byte
alignment.
This document defines the following new types:
+-------+-------------------------+-----------------------------+
+======+=====================+==================+
| Type | Description | Value defined in |
| | | Defined In |
+-------+-------------------------+-----------------------------+
+======+=====================+==================+
| TBD5 256 | Route Distinguisher | [This.I-D] RFC 9168 |
+-------+-------------------------+-----------------------------+
+------+---------------------+------------------+
| TBD6 257 | IPv4 Multicast Flow | [This.I-D] RFC 9168 |
+-------+-------------------------+-----------------------------+
+------+---------------------+------------------+
| TBD7 258 | IPv6 Multicast Flow | [This.I-D] RFC 9168 |
+-------+-------------------------+-----------------------------+
Figure 4:
+------+---------------------+------------------+
Table of 2: Flow Specification TLV Types defined Defined
in this
document Document
To allow identification of a VPN in PCEP via a Route Distinguisher
(RD) [RFC4364], a new TLV - TLV, ROUTE-DISTINGUISHER TLV TLV, is defined in
this document. A Flow Specification TLV with Type TBD5 256 (ROUTE-
DISTINGUISHER TLV) carries an RD Value, value, which is used to identify
that other flow filter information (for example, an IPv4 destination
prefix) is associated with a specific VPN identified by the RD. See
Section 8.6 for further discussion of VPN identification.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD5] Type=256 | Length=8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: 3: The Format of the ROUTE-DISTINGUISHER TLV
The format of the RD is as per [RFC4364].
Although it may be possible to describe a multicast Flow
Specification from the combination of other Flow Specification TLVs
with specific values, it is more convenient to use a dedicated Flow
Specification TLV. Flow Specification TLVs with Type values TBD6 257 and
TBD7
258 are used to identify a multicast flow for IPv4 and IPv6 IPv6,
respectively. The Value field is encoded as shown in Figure 6. 4.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |S|G| Src Mask Len | Grp Mask Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Source Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Group multicast Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: 4: Multicast Flow Specification TLV Encoding
The address fields and address mask lengths of the two Multicast Flow
Specification TLVs contain source and group prefixes for matching
against packet flows noting flows. Note that the two address fields are 32 bits
for an IPv4 Multicast Flow and 128 bits for an IPv6 Multicast Flow.
The Reserved field MUST be set to zero and ignored on receipt.
Two bit flags (S and G) are defined to describe the multicast
wildcarding in use. If the S bit is set, then source wildcarding is
in use use, and the values in the Source Mask Length and Source Address
fields MUST be ignored. If the G bit is set, then group wildcarding
is in use use, and the values in the Group Mask Length and Group
multicast Address fields MUST be ignored. The G bit MUST NOT be set
unless the S bit is also set: if a Multicast Flow Specification TLV
is received with S bit = 0 and G bit = 1 1, the receiver MUST respond
with a PCErr with Error-type TBD8 Error-Type 30 (FlowSpec Error) and error-value Error-value 2
(Malformed FlowSpec).
The three multicast mappings may be achieved as follows:
(S, G) - S bit = 0, G bit = 0, the Source Address and Group
multicast Address prefixes are both used to define the multicast
flow.
(*, G) - S bit = 1, G bit = 0, the Group multicast Address prefix
is used to define the multicast flow, but the Source Address
prefix is ignored.
(*, *) = - S bit = 1, G bit = 1, the Source Address and Group
multicast Address prefixes are both ignored.
7.1. L2 Flow Specification TLVs
The L2 Flow Filter TLV carries one or more L2 Flow Specification TLV.
The L2 Flow Specification TLV follows the format of all PCEP TLVs as
defined in [RFC5440]. However, the Type values are selected from a
separate IANA registry (see Section 10.4) rather than from the common
PCEP TLV registry.
Type values are chosen so that there can be commonality with L2 Flow
Specifications defined for use with BGP
[I-D.ietf-idr-flowspec-l2vpn]. This is possible because the BGP Flow
Spec encoding uses a single octet to encode the type where as PCEP
uses two octets. Thus the space of values for the Type field is
partitioned as shown in Figure 7.
Range |
---------------+-------------------------------------------------
0 .. 255 | Per BGP registry defined by
| [I-D.ietf-idr-flowspec-l2vpn].
| Not to be allocated in this registry.
|
256 .. 65535 | New PCEP Flow Specifications allocated according
| to the registry defined in this document.
Figure 7: L2 Flow Specification TLV Type Ranges
[I-D.ietf-idr-flowspec-l2vpn] is the reference for the registry "L2
Flow Spec Component Types" and defines the allocations it contains.
The content of the Value field in each TLV is specific to the type
and describes the parameters of the Flow Specification. The
definition of the format of many of these Value fields is inherited
from BGP specifications. Specifically, the inheritance is from
[I-D.ietf-idr-flowspec-l2vpn], but may also be inherited from future
BGP specifications.
When multiple L2 Flow Specification TLVs are present in a single L2
Flow Filter TLV they are combined to produce a more detailed
specification of a flow. Similarly, when both Flow Filter TLV and L2
Flow Filter TLV are present, they are combined to produce a more
detailed specification of a flow.
An implementation that receives a PCEP message carrying a L2 Flow
Specification TLV with a type value that it does not recognize or
does not support MUST respond with a PCErr message with error-type
TBD8 (FlowSpec Error), error-value 1 (Unsupported FlowSpec) and MUST
NOT install the Flow Specification.
All L2 Flow Specification TLVs with Types in the range 0 to 255 have
their Values interpretted as defined for use in BGP (for example, in
[I-D.ietf-idr-flowspec-l2vpn]) and are set using the BGP encoding,
but without the type octet (the relevant information is in the Type
field of the TLV). The Value field is padded with trailing zeros to
achieve 4-byte alignment.
This document defines no new types.
In the rest of the document when the Flow Specification is mentioned,
it includes the L2 Flow Specifications as well.
8. Detailed Procedures
This section outlines some specific detailed procedures for using the
protocol extensions defined in this document.
8.1. Default Behavior and Backward Compatibility
The default behavior is that no Flow Specification is applied to a
tunnel. That is, the default is that the FLOWSPEC object is not used
used, as is the case in all systems before the implementation of this
specification.
In this case, it is a local matter (such as through configuration)
how tunnel head ends are instructed in terms of what traffic to place
on a tunnel.
[RFC5440] describes how receivers respond when they see unknown PCEP
objects.
8.2. Composite Flow Specifications
Flow Specifications may be represented by a single Flow Specification
TLV or may require a more complex description using multiple Flow
Specification TLVs. For example, a flow indicated by a source-
destination pair of IPv6 addresses would be described by the
combination of Destination IPv6 Prefix and Source IPv6 Prefix Flow
Specification TLVs.
8.3. Modifying Flow Specifications
A PCE may want to modify a Flow Specification associated with a
tunnel, or a PCC may want to report a change to the Flow
Specification it is using with a tunnel.
It is important that to identify the specific Flow Specification is identified so
that it is
clear that this is a modification of an existing flow and not the
addition of a new flow as described in Section 8.4. The FS-
ID FS-ID field
of the PCEP FLOWSPEC object is used to identify a specific Flow
Specification in the context of the content of the Speaker Entity
Identifier TLV.
When modifying a Flow Specification, all Flow Specification TLVs for
the intended specification of the flow MUST be included in the PCEP
FLOWSPEC object. the The FS-ID MUST be retained from the previous
description of the flow, and the same Speaker Entity Identity Identifier TLV
MUST be used.
8.4. Multiple Flow Specifications
It is possible that traffic from multiple flows will be placed on a
single tunnel. In some cases cases, it is possible to define these within
a single PCEP FLOWSPEC object by widening the scope of a Flow
Specification TLV: for example, traffic to two destination IPv4
prefixes might be captured by a single Flow Specification TLV with
type 'Destination' "Destination" with a suitably adjusted prefix. However, this is
unlikely to be possible in most scenarios, and it must be recalled
that it is not permitted to include two Flow Specification TLVs of
the same type within one Flow Filter TLV.
The normal procedure, therefore, is to carry each Flow Specification
in its own PCEP FLOWSPEC object. Multiple objects may be present on
a single PCEP message, or multiple PCEP messages may be used.
8.5. Adding and Removing Flow Specifications
The Remove bit in the PCEP FLOWSPEC object is left clear when a Flow
Specification is being added or modified.
To remove a Flow Specification, a PCEP FLOWSPEC object is included
with the FS-ID matching the one being removed, and the R bit is set
to indicate removal. In this case case, it is not necessary to include
any Flow Specification TLVs.
If the R bit is set and Flow Specification TLVs are present, an
implementation MAY ignore them. If the implementation checks the
Flow Specification TLVs against those recorded for the FS-ID and
Speaker Entity Identity Identifier of the Flow Specification being removed and
finds a mismatch, the Flow Specification matching the FS-ID MUST
still be removed removed, and the implementation SHOULD record a local
exception or log.
8.6. VPN Identifiers
VPN instances are identified in BGP using Route Distinguishers (RDs) RDs [RFC4364]. These
values are not normally considered to have any meaning outside of the
network, and they are not encoded in data packets belonging to the
VPNs. However, RDs provide a useful way of identifying VPN instances
and are often manually or automatically assigned to VPNs as they are
provisioned.
Thus
Thus, the RD provides a useful way to indicate that traffic for a
particular VPN should be placed on a given tunnel. The tunnel head
end will need to interpret this Flow Specification not as a filter on
the fields of data packets, packets but rather using the other mechanisms that
it already uses to identify VPN traffic. This These mechanisms could be
based on the incoming port (for port-based VPNs) or may leverage
knowledge of the
VRF VPN Routing and Forwarding (VRF) that is in use for
the traffic.
8.7. Priorities and Overlapping Flow Specifications
Flow specifications Specifications can overlap. For example, two different flow
specifications Flow
Specifications may be identical except for the length of the prefix
in the destination address. In these cases cases, the PCC must determine
how to prioritize the flow specifications Flow Specifications so as to know to which path to
assign packets that match both flow specifications. Flow Specifications. That is, the PCC
must assign a precedence to the flow specifications Flow Specifications so that it checks
each incoming packet for a match in a predictable order.
The processing of BGP Flow Specifications is described in
[I-D.ietf-idr-rfc5575bis]. [RFC8955].
Section 5.1 of that document explains the order of traffic filtering
rules to be executed by an implementation of that specification.
PCCs MUST apply the same ordering rules as defined in
[I-D.ietf-idr-rfc5575bis]. [RFC8955].
Furthermore, it is possible that Flow Specifications will be
distributed by BGP as well as by PCEP as described in this document.
In such cases cases, implementations supporting both approaches MUST apply
the prioritization and ordering rules as set out in
[I-D.ietf-idr-rfc5575bis] [RFC8955]
regardless of which protocol distributed the Flow Specifications.
However, implementations MAY provide a configuration control to allow
one protocol to take precedence over the other as other; this may be
particularly useful if the Flow Specifications make identical matches
on traffic, traffic but have different actions. It is RECOMMENDED that a
message be logged for the operator to understand the behavior when
two Flow Specifications distributed by different protocols overlap, and
especially when one acts to replace another, that a message be logged for the operator to
understand the behaviour. another.
Section 13.1 12.1 of this document covers manageability considerations
relevant to the prioritized ordering of flow specifications. Flow Specifications.
An implementation that receives a PCEP message carrying a Flow
Specification that it cannot resolve against other Flow
Specifications already installed (for example, because the new Flow
Specification has irresolvable conflicts with other Flow
Specifications that are already installed) MUST respond with a PCErr
message with error-type TBD8 Error-Type 30 (FlowSpec Error), error-value Error) and Error-value 3
(Unresolvable Conflict) and MUST NOT install the Flow Specification.
9. PCEP Messages
This section describes the format of messages that contain FLOWSPEC
objects. The only difference to from previous message formats is the
inclusion of that object.
The figures in this section use the notation defined in [RFC5511].
The FLOWSPEC object is OPTIONAL and MAY be carried in the PCEP
messages.
The PCInitiate message is defined in [RFC8281] and updated as below:
<PCInitiate Message> ::= <Common Header>
<PCE-initiated-lsp-list>
Where:
<PCE-initiated-lsp-list> ::= <PCE-initiated-lsp-request>
[<PCE-initiated-lsp-list>]
<PCE-initiated-lsp-request> ::=
( <PCE-initiated-lsp-instantiation>|
<PCE-initiated-lsp-deletion> )
<PCE-initiated-lsp-instantiation> ::= <SRP>
<LSP>
[<END-POINTS>]
<ERO>
[<attribute-list>]
[<flowspec-list>]
Where:
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
The PCUpd message is defined in [RFC8231] and updated as below:
<PCUpd Message> ::= <Common Header>
<update-request-list>
Where:
<update-request-list> ::= <update-request>
[<update-request-list>]
<update-request> ::= <SRP>
<LSP>
<path>
[<flowspec-list>]
Where:
<path>::= <intended-path><intended-attribute-list>
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
The PCRpt message is defined in [RFC8231] and updated as below:
<PCRpt Message> ::= <Common Header>
<state-report-list>
Where:
<state-report-list> ::= <state-report>[<state-report-list>]
<state-report> ::= [<SRP>]
<LSP>
<path>
[<flowspec-list>]
Where:
<path>::= <intended-path>
[<actual-attribute-list><actual-path>]
<intended-attribute-list>
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
The PCReq message is defined in [RFC5440] and updated in [RFC8231], [RFC8231];
it is further updated below for flow specification: a Flow Specification:
<PCReq Message>::= <Common Header>
[<svec-list>]
<request-list>
Where:
<svec-list>::= <SVEC>[<svec-list>]
<request-list>::= <request>[<request-list>]
<request>::= <RP>
<END-POINTS>
[<LSP>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<RRO>[<BANDWIDTH>]]
[<IRO>]
[<LOAD-BALANCING>]
[<flowspec-list>]
Where:
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
The PCRep message is defined in [RFC5440] and updated in [RFC8231], [RFC8231];
it is further updated below for flow specification: a Flow Specification:
<PCRep Message> ::= <Common Header>
<response-list>
Where:
<response-list>::=<response>[<response-list>]
<response>::=<RP>
[<LSP>]
[<NO-PATH>]
[<attribute-list>]
[<path-list>]
[<flowspec-list>]
Where:
<flowspec-list> ::= <FLOWSPEC> [<flowspec-list>]
10. IANA Considerations
IANA maintains the "Path Computation Element Protocol (PCEP) Numbers"
registry.
This document requests that IANA actions to allocate code points for the
protocol elements defined in this document.
10.1. PCEP Objects
IANA maintains a subregistry called "PCEP Objects" within the "Path
Computation Element Protocol (PCEP) Numbers" registry. Each PCEP
object has an Object-Class and an Object-Type. IANA
maintains a subregistry called "PCEP Objects". Object-Type, and IANA is requested to
make an assignment from has allocated
new code points in this subregistry as follows:
Object-Class
+====================+==========+=======================+===========+
| Object-Class Value | Name | Object-Type | Reference
-------------+-------------+------------------------+----------------
TBD3 |
+====================+==========+=======================+===========+
| 43 | FLOWSPEC | 0: Reserved | [This.I-D] RFC 9168 |
| | +-----------------------+-----------+
| | | 1: Flow | RFC 9168 |
| | | Specification | [This.I-D] |
+--------------------+----------+-----------------------+-----------+
Table 3: PCEP Objects Subregistry Additions
10.1.1. PCEP FLOWSPEC Object Flag Field
This document requests that a new sub-registry, named subregistry, "FLOWSPEC Object Flag
Field", is be created within the "Path Computation Element Protocol
(PCEP) Numbers" registry to manage the Flag field of the FLOWSPEC
object. New values are to be assigned by Standards Action [RFC8126].
Each bit should be tracked with the following qualities:
o
* Bit number (counting from bit 0 as the most significant bit)
o
* Capability description
o
* Defining RFC
The initial population of this registry is as follows:
+=====+================+===========+
| Bit | Description | Reference
-----+--------------------+------------- |
+=====+================+===========+
| 0-5 | Unnassigned Unassigned | |
+-----+----------------+-----------+
| 6 | LPM (L bit) | [This.I-D] RFC 9168 |
+-----+----------------+-----------+
| 7 | Remove (R bit) | [This.I-D] RFC 9168 |
+-----+----------------+-----------+
Table 4: Initial Contents of the
FLOWSPEC Object Flag Field
Registry
10.2. PCEP TLV Type Indicators
IANA maintains a subregistry called "PCEP TLV Type Indicators". Indicators" within
the "Path Computation Element Protocol (PCEP) Numbers" registry.
IANA
is requested to make an assignment from has made the following allocations in this subregistry as follows: subregistry:
+=======+=============================+===========+
| Value | Meaning Description | Reference
--------+------------------------------+-------------
TBD2 |
+=======+=============================+===========+
| 51 | PCE-FLOWSPEC-CAPABILITY TLV | [This.I-D]
TBD4 RFC 9168 | FLOW FILTER TLV
+-------+-----------------------------+-----------+
| [This.I-D]
TBD9 52 | L2 FLOW FILTER TLV | [This.I-D] RFC 9168 |
+-------+-----------------------------+-----------+
Table 5: PCEP TLV Type Indicators Subregistry
Additions
10.3. Flow Specification TLV Type Indicators
IANA is requested to create has created a new subregistry call the called "PCEP Flow Specification
TLV Type Indicators" within the "Path Computation Element Protocol
(PCEP) Numbers" registry.
Allocations from this registry are to be made according to the
following assignment policies [RFC8126]:
+=============+===================================+
| Range | Assignment policy
---------------+---------------------------------------------------
0 .. 255 Registration Procedures |
+=============+===================================+
| 0-255 | Reserved - must not be allocated. |
| | |
| | Usage mirrors the BGP FlowSpec registry Flow Spec | [I-D.ietf-idr-rfc5575bis] and
| [I-D.ietf-idr-flow-spec-v6]. |
256 .. 64506 registry [RFC8955] [RFC8956]. |
+-------------+-----------------------------------+
| 256-64506 | Specification Required |
64507 .. 65531
+-------------+-----------------------------------+
| 64507-65531 | First Come First Served |
65532 .. 65535
+-------------+-----------------------------------+
| 65532-65535 | Experimental Use |
+-------------+-----------------------------------+
Table 6: Registration Procedures for the PCEP
Flow Specification TLV Type Indicators
Subregistry
IANA is requested to pre-populate has populated this registry with values defined in this document
as follows, taking the new values from the range 256 to 64506:
+=======+=====================+
| Value | Meaning
-------+------------------------
TBD5 |
+=======+=====================+
| 256 | Route Distinguisher
TBD6 |
+-------+---------------------+
| 257 | IPv4 Multicast
TBD7 |
+-------+---------------------+
| 258 | IPv6 Multicast
10.4. L2 Flow Specification TLV Type Indicators
IANA is requested to create a new subregistry called |
+-------+---------------------+
Table 7: Initial Contents
of the "PCEP L2 PCEP Flow
Specification TLV Type Indicators" registry.
Allocations from this registry are to be made according to the
following assignment policies [RFC8126]:
Range | Assignment policy
---------------+---------------------------------------------------
0 .. 255 | Reserved - must not be allocated.
| Usage mirrors the BGP L2 FlowSpec registry
| [I-D.ietf-idr-flowspec-l2vpn].
|
256 .. 64506 | Specification Required
|
64507 .. 65531 | First Come First Served
|
65532 .. 65535 | Experimental
10.5.
Indicators Subregistry
10.4. PCEP Error Codes
IANA maintains a subregistry called "PCEP-ERROR Object Error Types
and Values". Values" within the "Path Computation Element Protocol (PCEP)
Numbers" registry. Entries in this subregistry are described by
Error-Type and Error-value. IANA is requested to make has added the following assignment
from
to this subregistry:
Error-|
+============+================+=========================+===========+
| Error-Type | Meaning | Error-value | Reference
Type | |
+============+================+=========================+===========+
|
-------+--------------------+----------------------------+-----------
TBD8 30 | FlowSpec error | 0: Unassigned | [This.I-D] RFC 9168 |
| | +-------------------------+-----------+
| | | 1: Unsupported | RFC 9168 |
| | | FlowSpec | [This.I-D] |
| | +-------------------------+-----------+
| | | 2: Malformed | RFC 9168 |
| | | FlowSpec | [This.I-D] |
| | +-------------------------+-----------+
| | | 3: Unresolvable | RFC 9168 |
| | | Conflict | [This.I-D] |
| | +-------------------------+-----------+
| | | 4: Unknown | RFC 9168 |
| | | FlowSpec | [This.I-D] |
| | +-------------------------+-----------+
| | | 5: Unsupported | RFC 9168 |
| | | LPM Route | [This.I-D] |
| | +-------------------------+-----------+
| | | 6-255: | RFC 9168 |
| | | Unassigned | [This.I-D]
10.6. |
+------------+----------------+-------------------------+-----------+
Table 8: PCEP-ERROR Object Error Types and Values Subregistry
Additions
10.5. PCE Capability Flag
IANA maintains a subregistry called "Open Shortest Path First v2
(OSPFv2) Parameters" with has registered a sub-registry called new capability bit in the OSPF Parameters "Path
Computation Element (PCE) Capability Flags". IANA is requested to assign a new
capability bit from this Flags" registry as follows:
+=====+========================+===========+
| Bit | Capability Description | Reference
-------+-------------------------------+------------
TBD1 |
+=====+========================+===========+
| 16 | FlowSpec | [This.I-D]
11. Implementation Status
[NOTE TO RFC EDITOR : This whole section and the reference to RFC
7942 is to be removed before publication as an RFC]
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
At the time of posting the -12 version of this document, there are no
known implementations of this mechanism. It is believed that two
vendors are considering prototype implementations, but these plans
are too vague to make any further assertions.
12. 9168 |
+-----+------------------------+-----------+
Table 9: Path Computation Element (PCE)
Capability Flags Registry Additions
11. Security Considerations
We may assume that a system that utilizes a remote PCE is subject to
a number of vulnerabilities that could allow spurious LSPs or SR
paths to be established or that could result in existing paths being
modified or torn down. Such systems, therefore, apply security
considerations as described in [RFC5440], Section 2.5 of [RFC6952],
[RFC8253], and [I-D.ietf-idr-rfc5575bis]. [RFC8955].
The description of Flow Specifications associated with paths set up
or controlled by a PCE add adds a further detail that could be attacked
without tearing down LSPs or SR paths, paths but causing causes traffic to be
misrouted within the network. Therefore, the use of the security
mechanisms for PCEP referenced above is important.
Visibility into the information carried in PCEP does not have direct
privacy concerns for end-users' data, end users' data; however, knowledge of how data
is routed in a network may make that data more vulnerable. Of
course, the ability to interfere with the way data is routed also
makes the data more vulnerable. Furthermore, knowledge of the
connected end-points endpoints (such as multicast receivers or VPN sites) is
usually considered private customer information. Therefore,
implementations or deployments concerned with protecting privacy MUST
apply the mechanisms described in the documents referenced above: above, in
particular
particular, to secure the PCEP session using IPSec IPsec per Sections 10.4
to 10.6 of [RFC5440] or TLS per [RFC8253]. Note that TCP-MD5
security as originally suggested in [RFC5440] does not provide
sufficient security or privacy guarantees, guarantees and SHOULD NOT be relied
upon.
Experience with Flow Specifications in BGP systems indicates that
they can become complex and that the overlap of Flow Specifications
installed in different orders can lead to unexpected results.
Although this is not directly a security issue per se, the confusion
and unexpected forwarding behavior may be engineered or exploited by
an attacker. Furthermore, this complexity might give rise to a
situation where the forwarding behaviors might create gaps in the
monitoring and inspection of particular traffic or provide a path
that avoids expected mitigations. Therefore, implementers and
operators SHOULD pay careful attention to the Manageability
Considerations manageability
considerations described in Section 13 12 and familiarize themselves
with the careful explanations in [I-D.ietf-idr-rfc5575bis].
13. [RFC8955].
12. Manageability Considerations
The feature introduced by this document enables operational
manageability of networks operated in conjunction with a PCE and
using PCEP. Without this feature, but in In the case of a stateful active PCE or with PCE-initiated PCE-
initiated services, in the absence of this feature, additional manual
configuration is needed to tell the head-ends head ends what traffic to place
on the network services (LSPs, SR paths, etc.).
This section follows the advice and guidance of [RFC6123].
13.1.
12.1. Management of Multiple Flow Specifications
Experience with flow specification Flow Specification in BGP suggests that there can be
a lot of complexity when two or more flow specifications Flow Specifications overlap.
This can arise, for example, with addresses indicated using prefixes, prefixes
and could cause confusion about what traffic should be placed on
which path. Unlike the behavior in a distributed routing system, it
is not important to the routing stablity stability and consistency of the
network that each head-end implementation applies the same rules to
disambiguate overlapping Flow Specifications, but it is important
that:
o A
* a network operator can easily find out what traffic is being
placed on which path and why. This will facilitate analysis of
the network and diagnosis of faults.
o A
* a PCE is be able to correctly predict the effect of instructions it
gives to a PCC. This will ensure that traffic is correctly placed
on the network without causing congestion or other network
inefficiencies,
inefficiencies and that traffic is correctly delivered.
To that end, a PCC MUST enable an operator to view the the Flow
Specifications that it has installed, and these MUST be presented in
order of precedence such that when two Flow Specifications overlap,
the one that will be serviced with higher precedence is presented to
the operator first.
A discussion of precedence ordering for flow specifications Flow Specifications is found
in Section 8.7.
13.2.
12.2. Control of Function through Configuration and Policy
Support for the function described in this document implies that a
functional element that is capable of requesting that a PCE to compute
and control a path is also able to configure the specification of
what traffic should be placed on that path. Where there is a human
involved in this action, configuration of the Flow Specification must
be available through an interface (such as a graphical user interface
or a command line interface). Command Line Interface). Where a distinct software component
(i.e., one not co-implemented with the PCE) is used, a protocol
mechanism will be required that could be PCEP itself or could be a data model model,
such as extensions to the YANG model for requesting path computation [I-D.ietf-teas-yang-path-computation].
[TEAS-YANG-PATH].
Implementations MAY be constructed with a configurable switch to say
indicate whether they support the functions defined in this document.
Otherwise, such implementations MUST indicate that they support the
function as described in Section 4. If an implementation supports allows
configurable support of this function, that support MAY be
configurable per peer or once for the whole implementation.
As mentioned in Section 13.1, 12.1, a PCE implementation SHOULD provide a
mechanism to configure variations in the precedence ordering of Flow
Specifications per PCC.
13.3.
12.3. Information and Data Models
The YANG model in [I-D.ietf-pce-pcep-yang] [PCE-PCEP-YANG] can be used to model and monitor
PCEP states and messages. To make that YANG model useful for the
extensions described in this document, it would need to be augmented
to cover the new protocol elements.
Similarly, as noted in Section 13.2, 12.2, the YANG model defined in
[I-D.ietf-teas-yang-path-computation]
[TEAS-YANG-PATH] could be extended to allow the specification of Flow
Specifications.
Finally, as mentioned in Section 13.1, 12.1, a PCC implementation SHOULD
provide a mechanism to allow an operator to read the Flow
Specifications from a PCC and to understand in what order they will
be executed. This could be achieved using a new YANG model.
13.4.
12.4. Liveness Detection and Monitoring
The extensions defined in this document do not require any additional
liveness detection and monitoring support. See [RFC5440] and
[RFC5886] for more information.
13.5.
12.5. Verifying Correct Operation
The chief element of operation that needs to be verified (in addition
to the operation of the protocol elements as described in [RFC5440])
is the installation, precedence, and correct operation of the Flow
Specifications at a PCC.
In addition to the YANG model model, for reading Flow Specifications
described in Section 13.3, 12.3, tools may be needed to inject Operations
and Management (OAM) traffic at the PCC that matches specific
criteria so that it can be monitored as while traveling along the
desired path. Such tools are outside the scope of this document.
13.6.
12.6. Requirements on for Other Protocols and Functional Components
This document places no requirements on other protocols or
components.
13.7.
12.7. Impact on Network Operation
The use of the features described in this document clearly have an
important impact on network traffic since they cause traffic to be
routed on specific paths in the network. However, in practice, these
changes make no direct changes to the network operation because
traffic is already placed on those paths using some pre-existing
configuration mechanism. Thus, the significant change is the
reduction in mechanisms that have to be applied, applied rather than a change
to how the traffic is passed through the network.
14. Acknowledgements
Thanks to Julian Lucek, Sudhir Cheruathur, Olivier Dugeon, Jayant
Agarwal, Jeffrey Zhang, Acee Lindem, Vishnu Pavan Beeram, Julien
Meuric, Deborah Brungard, Eric Vyncke, Erik Kline, Benjamin Kaduk,
Martin Duke, Roman Danyliw, and Alvaro Retana for useful discussions
and comments.
15.
13. References
15.1.
13.1. Normative References
[I-D.ietf-idr-flow-spec-v6]
Loibl, C., Raszuk, R., and S. Hares, "Dissemination of
Flow Specification Rules for IPv6", draft-ietf-idr-flow-
spec-v6-17 (work in progress), October 2020.
[I-D.ietf-idr-flowspec-l2vpn]
Weiguo, H., Eastlake, D., Litkowski, S., and S. Zhuang,
"BGP Dissemination of L2 Flow Specification Rules", draft-
ietf-idr-flowspec-l2vpn-15 (work in progress), May 2020.
[I-D.ietf-idr-rfc5575bis]
Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
draft-ietf-idr-rfc5575bis-27 (work in progress), October
2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in Various Routing Protocol
Specifications", RFC 5511, DOI 10.17487/RFC5511, April
2009, <https://www.rfc-editor.org/info/rfc5511>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
[RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X.,
and D. Dhody, "Optimizations of Label Switched Path State
Synchronization Procedures for a Stateful PCE", RFC 8232,
DOI 10.17487/RFC8232, September 2017,
<https://www.rfc-editor.org/info/rfc8232>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>.
15.2.
[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/info/rfc8955>.
[RFC8956] Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
"Dissemination of Flow Specification Rules for IPv6",
RFC 8956, DOI 10.17487/RFC8956, December 2020,
<https://www.rfc-editor.org/info/rfc8956>.
13.2. Informative References
[I-D.gont-numeric-ids-sec-considerations]
[BGP-L2VPN]
Hao, W., Eastlake, D. E., Litkowski, S., and S. Zhuang,
"BGP Dissemination of L2 Flow Specification Rules", Work
in Progress, Internet-Draft, draft-ietf-idr-flowspec-
l2vpn-18, 24 October 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-l2vpn-18>.
[NUMERIC-IDS-SEC]
Gont, F. and I. Arce, "Security Considerations for
Transient Numeric Identifiers Employed in Network
Protocols", draft-gont-numeric-ids-sec-considerations-05
(work Work in progress), July 2020.
[I-D.ietf-pce-pcep-yang] Progress, Internet-Draft, draft-gont-
numeric-ids-sec-considerations-06, 5 December 2020,
<https://datatracker.ietf.org/doc/html/draft-gont-numeric-
ids-sec-considerations-06>.
[PCE-PCEP-YANG]
Dhody, D., Hardwick, J., Beeram, V., V. P., and J. Tantsura,
"A YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep-
yang-14 (work in progress), July 2020.
[I-D.ietf-teas-yang-path-computation]
Busi, I., Belotti, S., Lopez, V., Sharma, A., and Y. Shi,
"Yang model for requesting Path Computation", draft-ietf-
teas-yang-path-computation-10 (work in progress), July
2020. Work in Progress,
Internet-Draft, draft-ietf-pce-pcep-yang-17, 23 October
2021, <https://datatracker.ietf.org/doc/html/draft-ietf-
pce-pcep-yang-17>.
[RFC4655] Farrel, A., Vasseur, J., J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "OSPF Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088,
January 2008, <https://www.rfc-editor.org/info/rfc5088>.
[RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5089, DOI 10.17487/RFC5089,
January 2008, <https://www.rfc-editor.org/info/rfc5089>.
[RFC5886] Vasseur, JP., Ed., Le Roux, JL., and Y. Ikejiri, "A Set of
Monitoring Tools for Path Computation Element (PCE)-Based
Architecture", RFC 5886, DOI 10.17487/RFC5886, June 2010,
<https://www.rfc-editor.org/info/rfc5886>.
[RFC6123] Farrel, A., "Inclusion of Manageability Sections in Path
Computation Element (PCE) Working Group Drafts", RFC 6123,
DOI 10.17487/RFC6123, February 2011,
<https://www.rfc-editor.org/info/rfc6123>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<https://www.rfc-editor.org/info/rfc6952>.
[RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path
Computation Element Architecture", RFC 7399,
DOI 10.17487/RFC7399, October 2014,
<https://www.rfc-editor.org/info/rfc7399>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An
Architecture for Use of PCE and the PCE Communication
Protocol (PCEP) in a Network with Central Control",
RFC 8283, DOI 10.17487/RFC8283, December 2017,
<https://www.rfc-editor.org/info/rfc8283>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "Path Computation Element Communication
Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
DOI 10.17487/RFC8664, December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
Appendix A.
[TEAS-YANG-PATH]
Busi, I., Belotti, S., Lopez, V., Sharma, A., and Y. Shi,
"YANG Data Model for requesting Path Computation", Work in
Progress, Internet-Draft, draft-ietf-teas-yang-path-
computation-16, 6 September 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
yang-path-computation-16>.
Acknowledgements
Thanks to Julian Lucek, Sudhir Cheruathur, Olivier Dugeon, Jayant
Agarwal, Jeffrey Zhang, Acee Lindem, Vishnu Pavan Beeram, Julien
Meuric, Deborah Brungard, Éric Vyncke, Erik Kline, Benjamin Kaduk,
Martin Duke, Roman Danyliw, and Alvaro Retana for useful discussions
and comments.
Contributors
Shankara
Huawei Technologies
Divyashree Techno Park, Whitefield Bangalore,
Karnataka
Bangalore 560066
Karnataka
India
Email: shankara@huawei.com
Qiandeng Liang
Huawei Technologies
Yuhuatai District
101 Software Avenue,
Yuhuatai District
Nanjing
Nanjing, 210012
China
Email: liangqiandeng@huawei.com
Cyril Margaria
Juniper Networks
200 Somerset Corporate Boulevard, Suite 4001
Bridgewater, NJ 08807
USA
United States of America
Email: cmargaria@juniper.net
Colby Barth
Juniper Networks
200 Somerset Corporate Boulevard, Suite 4001
Bridgewater, NJ 08807
USA
United States of America
Email: cbarth@juniper.net
Xia Chen
Huawei Technologies
Huawei Bld., No.156 No. 156 Beiqing Rd.
Beijing
Beijing, 100095
China
Email: jescia.chenxia@huawei.com
Shunwan Zhuang
Huawei Technologies
Huawei Bld., No.156 No. 156 Beiqing Rd.
Beijing
Beijing, 100095
China
Email: zhuangshunwan@huawei.com
Cheng Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
Beijing, 100095
China
Email: c.l@huawei.com
Authors' Addresses
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka
Bangalore 560066
Karnataka
India
Email: dhruv.ietf@gmail.com
Adrian Farrel
Old Dog Consulting
Email: adrian@olddog.co.uk
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Bldg., No. 156 Beiqing Rd.
Beijing
100095
China
Email: lizhenbin@huawei.com