rfc9284.original   rfc9284.txt 
Network Working Group M. Boucadair Internet Engineering Task Force (IETF) M. Boucadair
Internet-Draft Orange Request for Comments: 9284 Orange
Intended status: Informational T. Reddy.K Category: Informational T. Reddy.K
Expires: 28 October 2022 Akamai ISSN: 2070-1721 Nokia
W. Pan W. Pan
Huawei Technologies Huawei Technologies
26 April 2022 August 2022
Multi-homing Deployment Considerations for Distributed-Denial-of-Service Multihoming Deployment Considerations for DDoS Open Threat Signaling
Open Threat Signaling (DOTS) (DOTS)
draft-ietf-dots-multihoming-13
Abstract Abstract
This document discusses multi-homing considerations for Distributed- This document discusses multihoming considerations for DDoS Open
Denial-of-Service Open Threat Signaling (DOTS). The goal is to Threat Signaling (DOTS). The goal is to provide some guidance for
provide some guidance for DOTS clients and client-domain DOTS DOTS clients and client-domain DOTS gateways when multihomed.
gateways when multihomed.
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 informational purposes.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." 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.
This Internet-Draft will expire on 28 October 2022. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9284.
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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents
license-info) in effect on the date of publication of this document. (https://trustee.ietf.org/license-info) in effect on the date of
Please review these documents carefully, as they describe your rights publication of this document. Please review these documents
and restrictions with respect to this document. Code Components carefully, as they describe your rights and restrictions with respect
extracted from this document must include Revised BSD License text as to this document. Code Components extracted from this document must
described in Section 4.e of the Trust Legal Provisions and are include Revised BSD License text as described in Section 4.e of the
provided without warranty as described in the Revised BSD License. Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Language
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology
4. Multi-Homing Scenarios . . . . . . . . . . . . . . . . . . . 5 4. Multihoming Scenarios
4.1. Multi-Homed Residential Single CPE . . . . . . . . . . . 5 4.1. Multihomed Residential: Single CPE
4.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream 4.2. Multihomed Enterprise: Single CPE, Multiple Upstream ISPs
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.3. Multihomed Enterprise: Multiple CPEs, Multiple Upstream
4.3. Multi-homed Enterprise: Multiple CPEs, Multiple Upstream ISPs
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.4. Multihomed Enterprise with the Same ISP
4.4. Multi-homed Enterprise with the Same ISP . . . . . . . . 7 5. DOTS Multihoming Deployment Considerations
5. DOTS Multi-homing Deployment Considerations . . . . . . . . . 8 5.1. Residential CPE
5.1. Residential CPE . . . . . . . . . . . . . . . . . . . . . 8 5.2. Multihomed Enterprise: Single CPE, Multiple Upstream ISPs
5.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream 5.3. Multihomed Enterprise: Multiple CPEs, Multiple Upstream
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 10 ISPs
5.3. Multi-Homed Enterprise: Multiple CPEs, Multiple Upstream 5.4. Multihomed Enterprise: Single ISP
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6. Security Considerations
5.4. Multi-Homed Enterprise: Single ISP . . . . . . . . . . . 13 7. IANA Considerations
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. References
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8.1. Normative References
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 8.2. Informative References
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 Acknowledgements
9.1. Normative References . . . . . . . . . . . . . . . . . . 15 Authors' Addresses
9.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
In many deployments, it may not be possible for a network to In many deployments, it may not be possible for a network to
determine the cause of a distributed Denial-of-Service (DoS) attack determine the cause of a DDoS attack [RFC4732]. Rather, the network
[RFC4732]. Rather, the network may just realize that some resources may just realize that some resources appear to be under attack. To
appear to be under attack. To help with such situations, the IETF help with such situations, the IETF has specified the DDoS Open
has specified the DDoS Open Threat Signaling (DOTS) architecture Threat Signaling (DOTS) architecture [RFC8811], where a DOTS client
[RFC8811], where a DOTS client can inform an upstream DOTS server can inform an upstream DOTS server that its network is under a
that its network is under a potential attack and that appropriate potential attack and that appropriate mitigation actions are
mitigation actions are required. The DOTS protocols can be used to required. The DOTS protocols can be used to coordinate real-time
coordinate real-time mitigation efforts which can evolve as the mitigation efforts that can evolve as the attacks mutate, thereby
attacks mutate, thereby reducing the impact of an attack and leading reducing the impact of an attack and leading to more-efficient
to more efficient responsive actions. [RFC8903] identifies a set of responsive actions. [RFC8903] identifies a set of scenarios for
scenarios for DOTS; most of these scenarios involve a Customer DOTS; most of these scenarios involve a Customer Premises Equipment
Premises Equipment (CPE). (CPE).
The high-level base DOTS architecture is illustrated in Figure 1 The high-level base DOTS architecture is illustrated in Figure 1
([RFC8811]): (repeated from Section 2 of [RFC8811]):
+-----------+ +-------------+ +-----------+ +-------------+
| Mitigator | ~~~~~~~~~~ | DOTS Server | | Mitigator | ~~~~~~~~~~ | DOTS Server |
+-----------+ +-------------+ +-----------+ +-------------+
| |
| |
| |
+---------------+ +-------------+ +---------------+ +-------------+
| Attack Target | ~~~~~~ | DOTS Client | | Attack Target | ~~~~~~ | DOTS Client |
+---------------+ +-------------+ +---------------+ +-------------+
Figure 1: Basic DOTS Architecture Figure 1: Basic DOTS Architecture
[RFC8811] specifies that the DOTS client may be provided with a list [RFC8811] specifies that the DOTS client may be provided with a list
of DOTS servers; each of these servers is associated with one or more of DOTS servers; each of these servers is associated with one or more
IP addresses. These addresses may or may not be of the same address IP addresses. These addresses may or may not be of the same address
family. The DOTS client establishes one or more DOTS sessions by family. The DOTS client establishes one or more DOTS sessions by
connecting to the provided DOTS server(s) addresses (e.g., by using connecting to the provided addresses for the DOTS server or servers
[RFC8973]). [RFC8973].
DOTS may be deployed within networks that are connected to one single DOTS may be deployed within networks that are connected to one single
upstream provider. DOTS can also be enabled within networks that are upstream provider. DOTS can also be enabled within networks that are
multi-homed. The reader may refer to [RFC3582] for an overview of multihomed. The reader may refer to [RFC3582] for an overview of
multi-homing goals and motivations. This document discusses DOTS multihoming goals and motivations. This document discusses DOTS
multi-homing considerations. Specifically, the document aims to: multihoming considerations. Specifically, the document aims to:
1. Complete the base DOTS architecture with multi-homing specifics. 1. Complete the base DOTS architecture with multihoming specifics.
Those specifics need to be taken into account because: Those specifics need to be taken into account because:
* Sending a DOTS mitigation request to an arbitrary DOTS server * Sending a DOTS mitigation request to an arbitrary DOTS server
will not necessarily help in mitigating a DDoS attack. will not necessarily help in mitigating a DDoS attack.
* Randomly replicating all DOTS mitigation requests among all * Randomly replicating all DOTS mitigation requests among all
available DOTS servers is suboptimal. available DOTS servers is suboptimal.
* Sequentially contacting DOTS servers may increase the delay * Sequentially contacting DOTS servers may increase the delay
before a mitigation plan is enforced. before a mitigation plan is enforced.
2. Identify DOTS deployment schemes in a multi-homing context, where 2. Identify DOTS deployment schemes in a multihoming context, where
DOTS services can be offered by all or a subset of upstream DOTS services can be offered by all or a subset of upstream
providers. providers.
3. Provide guidelines and recommendations for placing DOTS requests 3. Provide guidelines and recommendations for placing DOTS requests
in multi-homed networks, e.g.,: in multihomed networks, for example:
* Select the appropriate DOTS server(s). * Select the appropriate DOTS server(s).
* Identify cases where anycast is not recommended for DOTS. * Identify cases where anycast is not recommended for DOTS.
This document adopts the following methodology: This document adopts the following methodology:
* Identify and extract viable deployment candidates from [RFC8903]. * Identify and extract viable deployment candidates from [RFC8903].
* Augment the description with multi-homing technicalities, e.g., * Augment the description with multihoming technicalities, for
example:
- One vs. multiple upstream network providers - One vs. multiple upstream network providers
- One vs. multiple interconnect routers - One vs. multiple interconnect routers
- Provider-Independent (PI) vs. Provider-Aggregatable (PA) IP - Provider-Independent (PI) vs. Provider-Aggregatable (PA) IP
addresses addresses
* Describe the recommended behavior of DOTS clients and client- * Describe the recommended behavior of DOTS clients and client-
domain DOTS gateways for each case. domain DOTS gateways for each case.
Multi-homed DOTS agents are assumed to make use of the protocols Multihomed DOTS agents are assumed to make use of the protocols
defined in [RFC9132] and [RFC8783]. This document does not require defined in [RFC9132] and [RFC8783]. This document does not require
any specific extension to the base DOTS protocols for deploying DOTS any specific extension to the base DOTS protocols for deploying DOTS
in a multi-homed context. in a multihomed context.
2. Requirements Language 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.
3. Terminology 3. Terminology
This document makes use of the terms defined in [RFC8811], [RFC8612], This document makes use of the terms defined in [RFC8811], [RFC8612],
and [RFC4116]. In particular: and [RFC4116]. In particular:
Provider-Aggregatable (PA) addresses: globally-unique addresses Provider-Aggregatable (PA) addresses: globally unique addresses
assigned by a transit provider to a customer. The addresses are assigned by a transit provider to a customer. The addresses are
considered "aggregatable" because the set of routes corresponding considered "aggregatable" because the set of routes corresponding
to the PA addresses are usually covered by an aggregate route set to the PA addresses are usually covered by an aggregate route set
corresponding to the address space operated by the transit corresponding to the address space operated by the transit
provider, from which the assignment was made (Section 2 of provider, from which the assignment was made (Section 2 of
[RFC4116]). [RFC4116]).
Provider-Independent (PI) addresses: globally-unique addresses that Provider-Independent (PI) addresses: globally unique addresses that
are not assigned by a transit provider, but are provided by some are not assigned by a transit provider, but are provided by some
other organisation, usually a Regional Internet Registry (RIR) other organization, usually a Regional Internet Registry (RIR)
(Section 2 of [RFC4116]). (Section 2 of [RFC4116]).
IP indifferently refers to IPv4 or IPv6. IP indifferently refers to IPv4 or IPv6.
4. Multi-Homing Scenarios 4. Multihoming Scenarios
This section describes some multi-homing scenarios that are relevant This section describes some multihoming scenarios that are relevant
to DOTS. In the following subsections, only the connections of to DOTS. In the following subsections, only the connections of
border routers are shown; internal network topologies are not border routers are shown; internal network topologies are not
elaborated. elaborated.
A multihomed network may enable DOTS for all or a subset of its A multihomed network may enable DOTS for all or a subset of its
upstream interconnection links. In such a case, DOTS servers can be upstream interconnection links. In such a case, DOTS servers can be
explicitly configured or dynamically discovered by a DOTS client explicitly configured or dynamically discovered by a DOTS client
using means such as those discussed in [RFC8973]. These DOTS servers using means such as those discussed in [RFC8973]. These DOTS servers
can be owned by the upstream provider, managed by a third-party can be owned by the upstream provider, managed by a third-party
(e.g., mitigation service provider), or a combination thereof. (e.g., mitigation service provider), or a combination thereof.
If a DOTS server is explicitly configured, it is assumed that an If a DOTS server is explicitly configured, it is assumed that an
interface is also provided to bind the DOTS service to an interface is also provided to bind the DOTS service to an
interconnection link. If no interface is provided, this means that interconnection link. If no interface is provided, the DOTS server
the DOTS server can be reached via any active interface. can be reached via any active interface.
This section distinguishes between residential CPEs vs. enterprise This section distinguishes between residential CPEs and enterprise
CPEs because PI addresses may be used for enterprises while this is CPEs because PI addresses may be used for enterprises, which is not
not the current practice for residential CPEs. the current practice for residential CPEs.
In the following subsections, all or a subset of interconnection In the following subsections, all or a subset of interconnection
links are associated with DOTS servers. links are associated with DOTS servers.
4.1. Multi-Homed Residential Single CPE 4.1. Multihomed Residential: Single CPE
The scenario shown in Figure 2 is characterized as follows: The scenario shown in Figure 2 is characterized as follows:
* The home network is connected to the Internet using one single * The home network is connected to the Internet using one single
CPE. CPE.
* The CPE is connected to multiple provisioning domains (i.e., both * The CPE is connected to multiple provisioning domains (i.e., both
fixed and mobile networks). Provisioning domain (PvD) is fixed and mobile networks). Provisioning Domain (PvD) is
explained in [RFC7556]. explained in [RFC7556].
In a typical deployment scenario, these provisioning domains are In a typical deployment scenario, these provisioning domains are
owned by the same provider (see Section 1 of [RFC8803]). Such a owned by the same provider (Section 1 of [RFC8803]). Such a
deployment is meant to seamlessly use both fixed and cellular deployment is meant to seamlessly use both fixed and cellular
networks for bonding, faster hand-overs, or better resiliency networks for bonding, faster handovers, or better resiliency
purposes. purposes.
* Each of these provisioning domains assigns IP addresses/prefixes * Each of these provisioning domains assigns IP addresses or
to the CPE and provides additional configuration information such prefixes to the CPE and provides additional configuration
as a list of DNS servers, DNS suffixes associated with the information such as a list of DNS servers, DNS suffixes associated
network, default gateway address, and DOTS server's name with the network, the default gateway address, and the DOTS
[RFC8973]. These addresses/prefixes are assumed to be Provider- server's name [RFC8973]. These addresses or prefixes are assumed
Aggregatable (PA). to be Provider-Aggregatable (PA).
* Because of ingress filtering, packets forwarded by the CPE towards * Because of ingress filtering, packets forwarded by the CPE towards
a given provisioning domain must be sent with a source IP address a given provisioning domain must be sent with a source IP address
that was assigned by that domain [RFC8043]. that was assigned by that domain [RFC8043].
+-------+ +-------+ +-------+ +-------+
|Fixed | |Mobile | |Fixed | |Mobile |
|Network| |Network| |Network| |Network|
+---+---+ +---+---+ +---+---+ +---+---+
| | Service Providers | | Service Providers
............|....................|....................... ............|....................|.......................
+---------++---------+ Home Network +---------++---------+ Home Network
|| ||
+--++-+ +--++-+
| CPE | | CPE |
+-----+ +-----+
... (Internal Network) ... (Internal Network)
Figure 2: Typical Multi-homed Residential CPE Figure 2: Typical Multihomed Residential CPE
4.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream ISPs 4.2. Multihomed Enterprise: Single CPE, Multiple Upstream ISPs
The scenario shown in Figure 3 is characterized as follows: The scenario shown in Figure 3 is characterized as follows:
* The enterprise network is connected to the Internet using a single * The enterprise network is connected to the Internet using a single
router. router.
* That router is connected to multiple provisioning domains managed * That router is connected to multiple provisioning domains managed
by distinct administrative entities. by distinct administrative entities.
Unlike the previous scenario, two sub-cases can be considered for an Unlike the previous scenario, two sub-cases can be considered for an
enterprise network with regards to assigned addresses: enterprise network with regard to assigned addresses:
1. PI addresses/prefixes: The enterprise is the owner of the IP 1. PI addresses or prefixes: The enterprise is the owner of the IP
addresses/prefixes; the same address/prefix is then used when addresses or prefixes; the same address or prefix is then used
establishing communications over any of the provisioning domains. when establishing communications over any of the provisioning
domains.
2. PA addresses/prefixes: Each of the provisioning domains assigns 2. PA addresses or prefixes: Each of the provisioning domains
IP addresses/prefixes to the enterprise network. These assigns IP addresses or prefixes to the enterprise network.
addresses/prefixes are used when communicating over the These addresses or prefixes are used when communicating over the
provisioning domain that assigned them. provisioning domain that assigned them.
+------+ +------+ +------+ +------+
| ISP1 | | ISP2 | | ISP1 | | ISP2 |
+---+--+ +--+---+ +---+--+ +--+---+
| | Service Providers | | Service Providers
............|....................|....................... ............|....................|.......................
+---------++---------+ Enterprise Network +---------++---------+ Enterprise Network
|| ||
+--++-+ +--++-+
| CPE | | CPE |
+-----+ +-----+
... (Internal Network) ... (Internal Network)
Figure 3: Multi-homed Enterprise Network (Single CPE connected to Figure 3: Multihomed Enterprise Network (Single CPE Connected to
Multiple Networks) Multiple Networks)
4.3. Multi-homed Enterprise: Multiple CPEs, Multiple Upstream ISPs 4.3. Multihomed Enterprise: Multiple CPEs, Multiple Upstream ISPs
This scenario is similar to the one described in Section 4.2; the This scenario is similar to the one described in Section 4.2; the
main difference is that dedicated routers (CPE1 and CPE2) are used to main difference is that dedicated routers (CPE1 and CPE2) are used to
connect to each provisioning domain. connect to each provisioning domain.
+------+ +------+ +------+ +------+
| ISP1 | | ISP2 | | ISP1 | | ISP2 |
+---+--+ +--+---+ +---+--+ +--+---+
| | Service Providers | | Service Providers
......................|..........|....................... ......................|..........|.......................
| | Enterprise Network | | Enterprise Network
+---+--+ +--+---+ +---+--+ +--+---+
| CPE1 | | CPE2 | | CPE1 | | CPE2 |
+------+ +------+ +------+ +------+
... (Internal Network) ... (Internal Network)
Figure 4: Multi-homed Enterprise Network (Multiple CPEs, Multiple Figure 4: Multihomed Enterprise Network (Multiple CPEs, Multiple
ISPs) ISPs)
4.4. Multi-homed Enterprise with the Same ISP 4.4. Multihomed Enterprise with the Same ISP
This scenario is a variant of Sections 4.2 and 4.3 in which multi- This scenario is a variant of Sections 4.2 and 4.3 in which
homing is supported by the same ISP (i.e., same provisioning domain). multihoming is supported by the same ISP (i.e., same provisioning
domain).
5. DOTS Multi-homing Deployment Considerations 5. DOTS Multihoming Deployment Considerations
Table 1 provides some sample, non-exhaustive, deployment schemes to Table 1 provides some sample, non-exhaustive deployment schemes to
illustrate how DOTS agents may be deployed for each of the scenarios illustrate how DOTS agents may be deployed for each of the scenarios
introduced in Section 4. introduced in Section 4.
+=========================+=======================+===============+ +=========================+=======================+===============+
| Scenario | DOTS client | Client-domain | | Scenario | DOTS Client | Client-Domain |
| | | DOTS gateway | | | | DOTS Gateway |
+=========================+=======================+===============+ +=========================+=======================+===============+
| Residential CPE | CPE | N/A | | Residential CPE | CPE | N/A |
+-------------------------+-----------------------+---------------+ +-------------------------+-----------------------+---------------+
| Single CPE, Multiple | Internal hosts or CPE | CPE | | Single CPE, multiple | Internal hosts or CPE | CPE |
| provisioning domains | | | | provisioning domains | | |
+-------------------------+-----------------------+---------------+ +-------------------------+-----------------------+---------------+
| Multiple CPEs, Multiple | Internal hosts or all | CPEs (CPE1 | | Multiple CPEs, multiple | Internal hosts or all | CPEs (CPE1 |
| provisioning domains | CPEs (CPE1 and CPE2) | and CPE2) | | provisioning domains | CPEs (CPE1 and CPE2) | and CPE2) |
+-------------------------+-----------------------+---------------+ +-------------------------+-----------------------+---------------+
| Multi-homed enterprise, | Internal hosts or all | CPEs (CPE1 | | Multihomed enterprise, | Internal hosts or all | CPEs (CPE1 |
| Single provisioning | CPEs (CPE1 and CPE2) | and CPE2) | | single provisioning | CPEs (CPE1 and CPE2) | and CPE2) |
| domain | | | | domain | | |
+-------------------------+-----------------------+---------------+ +-------------------------+-----------------------+---------------+
Table 1: Sample Deployment Cases Table 1: Sample Deployment Cases
These deployment schemes are further discussed in the following These deployment schemes are further discussed in the following
subsections. subsections.
5.1. Residential CPE 5.1. Residential CPE
skipping to change at page 9, line 23 skipping to change at line 379
CPE \ CPE \
\ \
\ +--+ \ +--+
----------|S2| ----------|S2|
+--+ +--+
DOTS Server Domain #2 DOTS Server Domain #2
Figure 5: DOTS Associations for a Multihomed Residential CPE Figure 5: DOTS Associations for a Multihomed Residential CPE
The DOTS client MUST resolve the DOTS server's name provided by each The DOTS client MUST resolve the DOTS server's name provided by each
provisioning domain using either the DNS servers learned from the provisioning domain using the DNS servers either learned from the
respective provisioning domain or from the DNS servers associated respective provisioning domain or associated with the interface(s)
with the interface(s) for which a DOTS server was explicitly for which a DOTS server was explicitly configured (Section 4).
configured (Section 4). IPv6-capable DOTS clients MUST use the IPv6-capable DOTS clients MUST use the source address selection
source address selection algorithm defined in [RFC6724] to select the algorithm defined in [RFC6724] to select the candidate source
candidate source addresses to contact each of these DOTS servers. addresses to contact each of these DOTS servers. DOTS sessions MUST
DOTS sessions MUST be established and MUST be maintained with each of be established and MUST be maintained with each of the DOTS servers
the DOTS servers because the mitigation scope of each of these because the mitigation scope of each of these servers is restricted.
servers is restricted. The DOTS client MUST use the security The DOTS client MUST use the security credentials (a certificate,
credentials (a certificate, typically) provided by a provisioning typically) provided by a provisioning domain to authenticate itself
domain to authenticate itself to the DOTS server(s) provided by the to the DOTS server(s) provided by the same provisioning domain. How
same provisioning domain. How such security credentials are provided such security credentials are provided to the DOTS client is out of
to the DOTS client is out of the scope of this document. The reader the scope of this document. The reader may refer to Section 7.1 of
may refer to Section 7.1 of [RFC9132] for more details about DOTS [RFC9132] for more details about DOTS authentication methods.
authentication methods.
When conveying a mitigation request to protect the attack target(s), When conveying a mitigation request to protect the attack target(s),
the DOTS client MUST select an available DOTS server whose network the DOTS client MUST select an available DOTS server whose network
has assigned the IP prefixes from which target prefixes/addresses are has assigned the IP prefixes from which target addresses or prefixes
derived. This implies that if no appropriate DOTS server is found, are derived. This implies that if no appropriate DOTS server is
the DOTS client MUST NOT send the mitigation request to any other found, the DOTS client MUST NOT send the mitigation request to any
available DOTS server. other available DOTS server.
For example, a mitigation request to protect target resources bound For example, a mitigation request to protect target resources bound
to a PA IP address/prefix cannot be satisfied by a provisioning to a PA IP address or prefix cannot be satisfied by a provisioning
domain other than the one that owns those addresses/prefixes. domain other than the one that owns those addresses or prefixes.
Consequently, if a CPE detects a DDoS attack that spreads over all Consequently, if a CPE detects a DDoS attack that spreads over all
its network attachments, it MUST contact all DOTS servers for its network attachments, it MUST contact all DOTS servers for
mitigation purposes. mitigation purposes.
The DOTS client MUST be able to associate a DOTS server with each The DOTS client MUST be able to associate a DOTS server with each
provisioning domain it serves. For example, if the DOTS client is provisioning domain it serves. For example, if the DOTS client is
provisioned with S1 using DHCP when attaching to a first network and provisioned with S1 using DHCP when attaching to a first network and
with S2 using Protocol Configuration Option (PCO) [TS.24008] when with S2 using Protocol Configuration Option (PCO) [TS.24008] when
attaching to a second network, the DOTS client must record the attaching to a second network, the DOTS client must record the
interface from which a DOTS server was provisioned. A DOTS signaling interface from which a DOTS server was provisioned. A DOTS signaling
session to a given DOTS server must be established using the session to a given DOTS server must be established using the
interface from which the DOTS server was provisioned. If a DOTS interface from which the DOTS server was provisioned. If a DOTS
server is explicitly configured, DOTS signaling with that server must server is explicitly configured, DOTS signaling with that server must
be established via the interfaces that are indicated in the explicit be established via the interfaces that are indicated in the explicit
configuration or via any active interface if no interface is configuration or via any active interface if no interface is
configured. configured.
5.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream ISPs 5.2. Multihomed Enterprise: Single CPE, Multiple Upstream ISPs
Figure 6 illustrates the DOTS sessions that can be established with a Figure 6 illustrates the DOTS sessions that can be established with a
client-domain DOTS gateway (hosted within the CPE as per Table 1), client-domain DOTS gateway (hosted within the CPE as per Table 1)
which is enabled within the context of the scenario described in that is enabled within the context of the scenario described in
Section 4.2. This deployment is characterized as follows: Section 4.2. This deployment is characterized as follows:
* One or more DOTS clients are enabled in hosts located in the * One or more DOTS clients are enabled in hosts located in the
internal network. internal network.
* A client-domain DOTS gateway is enabled to aggregate and then * A client-domain DOTS gateway is enabled to aggregate and then
relay the requests towards upstream DOTS servers. relay the requests towards upstream DOTS servers.
+--+ +--+
.................... ----------|S1| .................... ----------|S1|
skipping to change at page 11, line 5 skipping to change at line 454
. +---+ | . . +---+ | .
. | C2|----+ .\ . | C2|----+ .\
. +---+ . \ +--+ . +---+ . \ +--+
'..................' ----------|S2| '..................' ----------|S2|
+--+ +--+
DOTS Client Domain DOTS Server Domain #2 DOTS Client Domain DOTS Server Domain #2
Figure 6: Multiple DOTS Clients, Single DOTS Gateway, Multiple Figure 6: Multiple DOTS Clients, Single DOTS Gateway, Multiple
DOTS Servers DOTS Servers
When PA addresses/prefixes are in use, the same considerations When PA addresses or prefixes are in use, the same considerations
discussed in Section 5.1 need to be followed by the client-domain discussed in Section 5.1 need to be followed by the client-domain
DOTS gateway to contact its DOTS server(s). The client-domain DOTS DOTS gateway to contact its DOTS server(s). The client-domain DOTS
gateways can be reachable from DOTS clients by using a unicast gateways can be reachable from DOTS clients by using a unicast
address or an anycast address (Section 3.2.4 of [RFC8811]). address or an anycast address (Section 3.2.4 of [RFC8811]).
Nevertheless, when PI addresses/prefixes are assigned and absent any Nevertheless, when PI addresses or prefixes are assigned, and absent
policy, the client-domain DOTS gateway SHOULD send mitigation any policy, the client-domain DOTS gateway SHOULD send mitigation
requests to all its DOTS servers. Otherwise, the attack traffic may requests to all its DOTS servers. Otherwise, the attack traffic may
still be delivered via the ISP that hasn't received the mitigation still be delivered via the ISP that hasn't received the mitigation
request. request.
An alternate deployment model is depicted in Figure 7. This An alternate deployment model is depicted in Figure 7. This
deployment assumes that: deployment assumes that:
* One or more DOTS clients are enabled in hosts located in the * One or more DOTS clients are enabled in hosts located in the
internal network. These DOTS clients may use [RFC8973] to internal network. These DOTS clients may use [RFC8973] to
discover their DOTS server(s). discover their DOTS server(s).
skipping to change at page 11, line 45 skipping to change at line 494
| . . | | . . |
| . +--+ . | | . +--+ . |
+--------|C2|--------+ +--------|C2|--------+
. +--+ . . +--+ .
'........' '........'
DOTS Client DOTS Client
Domain Domain
Figure 7: Multiple DOTS Clients, Multiple DOTS Servers Figure 7: Multiple DOTS Clients, Multiple DOTS Servers
If PI addresses/prefixes are in use, the DOTS client MUST send a If PI addresses or prefixes are in use, the DOTS client MUST send a
mitigation request to all the DOTS servers. The use of the same mitigation request to all the DOTS servers. The use of the same
anycast addresses to reach these DOTS servers is NOT RECOMMENDED. If anycast addresses to reach these DOTS servers is NOT RECOMMENDED. If
a well-known anycast address is used to reach multiple DOTS servers, a well-known anycast address is used to reach multiple DOTS servers,
the CPE may not be able to select the appropriate provisioning domain the CPE may not be able to select the appropriate provisioning domain
to which the mitigation request should be forwarded. As a to which the mitigation request should be forwarded. As a
consequence, the request may not be forwarded to the appropriate DOTS consequence, the request may not be forwarded to the appropriate DOTS
server. server.
If PA addresses/prefixes are used, the same considerations discussed If PA addresses or prefixes are used, the same considerations
in Section 5.1 need to be followed by the DOTS clients. Because DOTS discussed in Section 5.1 need to be followed by the DOTS clients.
clients are not embedded in the CPE and multiple addresses/prefixes Because DOTS clients are not embedded in the CPE and multiple
may not be assigned to the DOTS client (typically in an IPv4 addresses or prefixes may not be assigned to the DOTS client
context), some issues may arise in how to steer traffic towards the (typically in an IPv4 context), some issues may arise in how to steer
appropriate DOTS server by using the appropriate source IP address. traffic towards the appropriate DOTS server by using the appropriate
These complications discussed in [RFC4116] are not specific to DOTS. source IP address. These complications discussed in [RFC4116] are
not specific to DOTS.
Another deployment approach is to enable many DOTS clients; each of Another deployment approach is to enable many DOTS clients; each of
them is responsible for handling communications with a specific DOTS them is responsible for handling communications with a specific DOTS
server (see Figure 8). server (see Figure 8).
.......... ..........
. +--+ . . +--+ .
+--------|C1| . +--------|C1| .
| . +--+ . | . +--+ .
+--+ . +--+ . +--+ +--+ . +--+ . +--+
|S2| . |C2|------|S1| |S2| . |C2|------|S1|
+--+ . +--+ . +--+ +--+ . +--+ . +--+
'........' '........'
DOTS Client DOTS Client
Domain Domain
Figure 8: Single Homed DOTS Clients Figure 8: Single-Homed DOTS Clients
For both deployments depicted in Figures 7 and 8, each DOTS client For both deployments depicted in Figures 7 and 8, each DOTS client
SHOULD be provided with policies (e.g., a prefix filter that is used SHOULD be provided with policies (e.g., a prefix filter that is used
to filter DDoS detection alarms) that will trigger DOTS to filter DDoS detection alarms) that will trigger DOTS
communications with the DOTS servers. Such policies will help the communications with the DOTS servers. Such policies will help the
DOTS client to select the appropriate destination DOTS server. The DOTS client to select the appropriate destination DOTS server. The
CPE MUST select the appropriate source IP address when forwarding CPE MUST select the appropriate source IP address when forwarding
DOTS messages received from an internal DOTS client. DOTS messages received from an internal DOTS client.
5.3. Multi-Homed Enterprise: Multiple CPEs, Multiple Upstream ISPs 5.3. Multihomed Enterprise: Multiple CPEs, Multiple Upstream ISPs
The deployments depicted in Figures 7 and 8 also apply to the The deployments depicted in Figures 7 and 8 also apply to the
scenario described in Section 4.3. One specific problem for this scenario described in Section 4.3. One specific problem for this
scenario is to select the appropriate exit router when contacting a scenario is to select the appropriate exit router when contacting a
given DOTS server. given DOTS server.
An alternative deployment scheme is shown in Figure 9: An alternative deployment scheme is shown in Figure 9:
* DOTS clients are enabled in hosts located in the internal network. * DOTS clients are enabled in hosts located in the internal network.
skipping to change at page 13, line 26 skipping to change at line 572
. CPE2 CPE1 . . CPE2 CPE1 .
. | +---+ | . . | +---+ | .
. +------------| C2|----+ . . +------------| C2|----+ .
. +---+ . . +---+ .
'...............................' '...............................'
DOTS Client Domain DOTS Client Domain
Figure 9: Multiple DOTS Clients, Multiple DOTS Gateways, Multiple Figure 9: Multiple DOTS Clients, Multiple DOTS Gateways, Multiple
DOTS Servers DOTS Servers
When PI addresses/prefixes are used, DOTS clients MUST contact all When PI addresses or prefixes are used, DOTS clients MUST contact all
the client-domain DOTS gateways to send a DOTS message. Client- the client-domain DOTS gateways to send a DOTS message. Client-
domain DOTS gateways will then relay the request to the DOTS servers domain DOTS gateways will then relay the request to the DOTS servers
as a function of local policy. Note that (same) anycast addresses as a function of local policy. Note that (same) anycast addresses
cannot be used to establish DOTS sessions between DOTS clients and cannot be used to establish DOTS sessions between DOTS clients and
client-domain DOTS gateways because only one DOTS gateway will client-domain DOTS gateways because only one DOTS gateway will
receive the mitigation request. receive the mitigation request.
When PA addresses/prefixes are used, but no filter rules are provided When PA addresses/prefixes are used, but no filter rules are provided
to DOTS clients, the latter MUST contact all client-domain DOTS to DOTS clients, the DOTS clients MUST contact all client-domain DOTS
gateways simultaneously to send a DOTS message. Upon receipt of a gateways simultaneously to send a DOTS message. Client-domain DOTS
request by a client-domain DOTS gateway, it MUST check whether the gateways MUST check whether a received request is to be forwarded
request is to be forwarded upstream (if the target IP prefix is upstream (if the target IP prefix is managed by the upstream server)
managed by the upstream server) or rejected. or rejected.
When PA addresses/prefixes are used, but specific filter rules are When PA addresses or prefixes are used, but specific filter rules are
provided to DOTS clients using some means that are out of scope of provided to DOTS clients using some means that are out of scope of
this document, the clients MUST select the appropriate client-domain this document, the clients MUST select the appropriate client-domain
DOTS gateway to reach. The use of the same anycast addresses is NOT DOTS gateway to reach. The use of the same anycast addresses is NOT
RECOMMENDED to reach client-domain DOTS gateways. RECOMMENDED to reach client-domain DOTS gateways.
5.4. Multi-Homed Enterprise: Single ISP 5.4. Multihomed Enterprise: Single ISP
The key difference of the scenario described in Section 4.4 compared The key difference between the scenario described in Section 4.4 and
to the other scenarios is that multi-homing is provided by the same the other scenarios is that multihoming is provided by the same ISP.
ISP. Concretely, that ISP can decide to provision the enterprise Concretely, that ISP can decide to provision the enterprise network
network with: with:
* The same DOTS server for all network attachments. * The same DOTS server for all network attachments.
* Distinct DOTS servers for each network attachment. These DOTS * Distinct DOTS servers for each network attachment. These DOTS
servers need to coordinate when a mitigation action is received servers need to coordinate when a mitigation action is received
from the enterprise network. from the enterprise network.
In both cases, DOTS agents enabled within the enterprise network MAY In both cases, DOTS agents enabled within the enterprise network MAY
decide to select one or all network attachments to send DOTS decide to select one or all network attachments to send DOTS
mitigation requests. mitigation requests.
6. Security Considerations 6. Security Considerations
A set of security threats related to multihoming are discussed in A set of security threats related to multihoming is discussed in
[RFC4218]. [RFC4218].
DOTS-related security considerations are discussed in Section 4 of DOTS-related security considerations are discussed in Section 5 of
[RFC8811]. [RFC8811].
DOTS clients should control the information that they share with peer DOTS clients should control the information that they share with peer
DOTS servers. In particular, if a DOTS client maintains DOTS DOTS servers. In particular, if a DOTS client maintains DOTS
sessions with specific DOTS servers per interconnection link, the sessions with specific DOTS servers per interconnection link, the
DOTS client SHOULD NOT leak information specific to a given link to DOTS client SHOULD NOT leak information specific to a given link to
DOTS servers on different interconnection links that are not DOTS servers on different interconnection links that are not
authorized to mitigate attacks for that given link. Whether this authorized to mitigate attacks for that given link. Whether this
constraint is relaxed is deployment-specific and must be subject to constraint is relaxed is deployment specific and must be subject to
explicit consent from the DOTS client domain administrator. How to explicit consent from the DOTS client domain administrator. How to
seek for such consent is implementation- and deployment-specific. seek such consent is implementation and deployment specific.
7. IANA Considerations 7. IANA Considerations
This document does not require any action from IANA. This document has no IANA actions.
8. Acknowledgements
Thanks to Roland Dobbins, Nik Teague, Jon Shallow, Dan Wing, and
Christian Jacquenet for sharing their comments on the mailing list.
Thanks to Kirill Kasavchenko for the comments.
Thanks to Kathleen Moriarty for the secdir review, Joel Jaeggli for
the opsdir review, Mirja Kuhlewind for the tsvart review, and Dave
Thaler for the Intdir review.
Many thanks to Roman Danyliw for the careful AD review.
Thanks to Lars Eggert, Robert Wilton, Paul Wouters, Erik Kline, and
Eric Vyncke for the IESG review.
9. References 8. References
9.1. Normative References 8.1. Normative References
[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/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown, [RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6 "Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012, (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012,
<https://www.rfc-editor.org/info/rfc6724>. <https://www.rfc-editor.org/info/rfc6724>.
[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/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8811] Mortensen, A., Ed., Reddy.K, T., Ed., Andreasen, F., [RFC8811] Mortensen, A., Ed., Reddy.K, T., Ed., Andreasen, F.,
Teague, N., and R. Compton, "DDoS Open Threat Signaling Teague, N., and R. Compton, "DDoS Open Threat Signaling
(DOTS) Architecture", RFC 8811, DOI 10.17487/RFC8811, (DOTS) Architecture", RFC 8811, DOI 10.17487/RFC8811,
August 2020, <https://www.rfc-editor.org/info/rfc8811>. August 2020, <https://www.rfc-editor.org/info/rfc8811>.
9.2. Informative References 8.2. Informative References
[RFC3582] Abley, J., Black, B., and V. Gill, "Goals for IPv6 Site- [RFC3582] Abley, J., Black, B., and V. Gill, "Goals for IPv6 Site-
Multihoming Architectures", RFC 3582, Multihoming Architectures", RFC 3582,
DOI 10.17487/RFC3582, August 2003, DOI 10.17487/RFC3582, August 2003,
<https://www.rfc-editor.org/info/rfc3582>. <https://www.rfc-editor.org/info/rfc3582>.
[RFC4116] Abley, J., Lindqvist, K., Davies, E., Black, B., and V. [RFC4116] Abley, J., Lindqvist, K., Davies, E., Black, B., and V.
Gill, "IPv4 Multihoming Practices and Limitations", Gill, "IPv4 Multihoming Practices and Limitations",
RFC 4116, DOI 10.17487/RFC4116, July 2005, RFC 4116, DOI 10.17487/RFC4116, July 2005,
<https://www.rfc-editor.org/info/rfc4116>. <https://www.rfc-editor.org/info/rfc4116>.
skipping to change at page 16, line 42 skipping to change at line 717
(DOTS) Agent Discovery", RFC 8973, DOI 10.17487/RFC8973, (DOTS) Agent Discovery", RFC 8973, DOI 10.17487/RFC8973,
January 2021, <https://www.rfc-editor.org/info/rfc8973>. January 2021, <https://www.rfc-editor.org/info/rfc8973>.
[RFC9132] Boucadair, M., Ed., Shallow, J., and T. Reddy.K, [RFC9132] Boucadair, M., Ed., Shallow, J., and T. Reddy.K,
"Distributed Denial-of-Service Open Threat Signaling "Distributed Denial-of-Service Open Threat Signaling
(DOTS) Signal Channel Specification", RFC 9132, (DOTS) Signal Channel Specification", RFC 9132,
DOI 10.17487/RFC9132, September 2021, DOI 10.17487/RFC9132, September 2021,
<https://www.rfc-editor.org/info/rfc9132>. <https://www.rfc-editor.org/info/rfc9132>.
[TS.24008] 3GPP, "Mobile radio interface Layer 3 specification; Core [TS.24008] 3GPP, "Mobile radio interface Layer 3 specification; Core
network protocols; Stage 3 (Release 16)", December 2019, network protocols; Stage 3", 3GPP TS 24.008 16.3.0,
<http://www.3gpp.org/DynaReport/24008.htm>. December 2019,
<https://www.3gpp.org/DynaReport/24008.htm>.
Acknowledgements
Thanks to Roland Dobbins, Nik Teague, Jon Shallow, Dan Wing, and
Christian Jacquenet for sharing their comments on the mailing list.
Thanks to Kirill Kasavchenko for the comments.
Thanks to Kathleen Moriarty for the secdir review, Joel Jaeggli for
the opsdir review, Mirja Kühlewind for the tsvart review, and Dave
Thaler for the intdir review.
Many thanks to Roman Danyliw for the careful AD review.
Thanks to Lars Eggert, Robert Wilton, Paul Wouters, Erik Kline, and
Éric Vyncke for the IESG review.
Authors' Addresses Authors' Addresses
Mohamed Boucadair Mohamed Boucadair
Orange Orange
35000 Rennes 35000 Rennes
France France
Email: mohamed.boucadair@orange.com Email: mohamed.boucadair@orange.com
Tirumaleswar Reddy.K Tirumaleswar Reddy.K
Akamai Nokia
Embassy Golf Link Business Park
Bangalore 560071
Karnataka
India
Email: kondtir@gmail.com Email: kondtir@gmail.com
Wei Pan Wei Pan
Huawei Technologies Huawei Technologies
Email: william.panwei@huawei.com Email: william.panwei@huawei.com
 End of changes. 75 change blocks. 
204 lines changed or deleted 201 lines changed or added

This html diff was produced by rfcdiff 1.48.