< draft-ietf-dots-multihoming-12.txt   draft-ietf-dots-multihoming-13.txt >
Network Working Group M. Boucadair Network Working Group M. Boucadair
Internet-Draft Orange Internet-Draft Orange
Intended status: Informational T. Reddy.K Intended status: Informational T. Reddy.K
Expires: 23 October 2022 Akamai Expires: 28 October 2022 Akamai
W. Pan W. Pan
Huawei Technologies Huawei Technologies
21 April 2022 26 April 2022
Multi-homing Deployment Considerations for Distributed-Denial-of-Service Multi-homing Deployment Considerations for Distributed-Denial-of-Service
Open Threat Signaling (DOTS) Open Threat Signaling (DOTS)
draft-ietf-dots-multihoming-12 draft-ietf-dots-multihoming-13
Abstract Abstract
This document discusses multi-homing considerations for Distributed- This document discusses multi-homing considerations for Distributed-
Denial-of-Service Open Threat Signaling (DOTS). The goal is to Denial-of-Service Open Threat Signaling (DOTS). The goal is to
provide some guidance for DOTS clients and client-domain DOTS provide some guidance for DOTS clients and client-domain DOTS
gateways when multihomed. gateways when multihomed.
Status of This Memo Status of This Memo
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This Internet-Draft will expire on 23 October 2022. This Internet-Draft will expire on 28 October 2022.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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5. DOTS Multi-homing Deployment Considerations . . . . . . . . . 8 5. DOTS Multi-homing Deployment Considerations . . . . . . . . . 8
5.1. Residential CPE . . . . . . . . . . . . . . . . . . . . . 8 5.1. Residential CPE . . . . . . . . . . . . . . . . . . . . . 8
5.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream 5.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 10 ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.3. Multi-Homed Enterprise: Multiple CPEs, Multiple Upstream 5.3. Multi-Homed Enterprise: Multiple CPEs, Multiple Upstream
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 12 ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.4. Multi-Homed Enterprise: Single ISP . . . . . . . . . . . 13 5.4. Multi-Homed Enterprise: Single ISP . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . 15 9.1. Normative References . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . 15 9.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 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 distributed Denial-of-Service (DoS) attack
[RFC4732]. Rather, the network may just realize that some resources [RFC4732]. Rather, the network may just realize that some resources
appear to be under attack. To help with such situations, the IETF appear to be under attack. To help with such situations, the IETF
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"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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 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: are 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: are globally-unique addresses Provider-Independent (PI) addresses: globally-unique addresses that
which are not assigned by a transit provider, but are provided by are not assigned by a transit provider, but are provided by some
some other organisation, usually a Regional Internet Registry other organisation, usually a Regional Internet Registry (RIR)
(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. Multi-Homing Scenarios
This section describes some multi-homing scenarios that are relevant This section describes some multi-homing 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.
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Figure 2: Typical Multi-homed Residential CPE Figure 2: Typical Multi-homed Residential CPE
4.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream ISPs 4.2. Multi-Homed 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 (i.e., * That router is connected to multiple provisioning domains managed
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 regards to assigned addresses:
1. PI addresses/prefixes: The enterprise is the owner of the IP 1. PI addresses/prefixes: The enterprise is the owner of the IP
addresses/prefixes; the same address/prefix is then used when addresses/prefixes; the same address/prefix is then used when
establishing communications over any of the provisioning domains. establishing communications over any of the provisioning domains.
2. PA addresses/prefixes: Each of the provisioning domains assigns 2. PA addresses/prefixes: Each of the provisioning domains assigns
IP addresses/prefixes to the enterprise network. These IP addresses/prefixes to the enterprise network. These
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domain other than the one that owns those addresses/prefixes. domain other than the one that owns those addresses/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. 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. Multi-Homed 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 which 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 of 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|
. +---+ . / +--+ . +---+ . / +--+
. | C1|----+ ./ DOTS Server Domain #1 . | C1|----+ ./ DOTS Server Domain #1
. +---+ | . . +---+ | .
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'..................' ----------|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/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 an 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/prefixes are assigned and absent any
policy, the client-domain DOTS gateway MUST send mitigation requests policy, the client-domain DOTS gateway SHOULD send mitigation
to all its DOTS servers. Otherwise, the attack traffic may still be requests to all its DOTS servers. Otherwise, the attack traffic may
delivered via the ISP which hasn't received the mitigation request. still be delivered via the ISP that hasn't received the mitigation
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).
* These DOTS clients communicate directly with upstream DOTS * These DOTS clients communicate directly with upstream DOTS
servers. servers.
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| . +--+ . | | . +--+ . |
+--------|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/prefixes are in use, the DOTS client MUST send a
mitigation request to all the DOTS servers. The use of anycast mitigation request to all the DOTS servers. The use of the same
addresses to reach these DOTS servers is NOT RECOMMENDED. If a well- anycast addresses to reach these DOTS servers is NOT RECOMMENDED. If
known anycast address is used to reach multiple DOTS servers, the CPE a well-known anycast address is used to reach multiple DOTS servers,
may not be able to select the appropriate provisioning domain to the CPE may not be able to select the appropriate provisioning domain
which the mitigation request should be forwarded. As a consequence, to which the mitigation request should be forwarded. As a
the request may not be forwarded to the appropriate DOTS server. consequence, the request may not be forwarded to the appropriate DOTS
server.
If PA addresses/prefixes are used, the same considerations discussed If PA addresses/prefixes are used, the same considerations discussed
in Section 5.1 need to be followed by the DOTS clients. Because DOTS in Section 5.1 need to be followed by the DOTS clients. Because DOTS
clients are not embedded in the CPE and multiple addresses/prefixes clients are not embedded in the CPE and multiple addresses/prefixes
may not be assigned to the DOTS client (typically in an IPv4 may not be assigned to the DOTS client (typically in an IPv4
context), some issues may arise in how to steer traffic towards the context), some issues may arise in how to steer traffic towards the
appropriate DOTS server by using the appropriate source IP address. appropriate DOTS server by using the appropriate source IP address.
These complications discussed in [RFC4116] are not specific to DOTS. 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
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. +---+ . . +---+ .
'...............................' '...............................'
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/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 anycast addresses cannot be as a function of local policy. Note that (same) anycast addresses
used to establish DOTS sessions between DOTS clients and client- cannot be used to establish DOTS sessions between DOTS clients and
domain DOTS gateways because only one DOTS gateway will receive the client-domain DOTS gateways because only one DOTS gateway will
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 latter MUST contact all client-domain DOTS
gateways simultaneously to send a DOTS message. Upon receipt of a gateways simultaneously to send a DOTS message. Upon receipt of a
request by a client-domain DOTS gateway, it MUST check whether the request by a client-domain DOTS gateway, it MUST check whether the
request is to be forwarded upstream (if the target IP prefix is request is to be forwarded upstream (if the target IP prefix is
managed by the upstream server) or rejected. managed by the upstream server) or rejected.
When PA addresses/prefixes are used, but specific filter rules are When PA addresses/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 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. Multi-Homed Enterprise: Single ISP
The key difference of the scenario described in Section 4.4 compared The key difference of the scenario described in Section 4.4 compared
to the other scenarios is that multi-homing is provided by the same to the other scenarios is that multi-homing is provided by the same
ISP. Concretely, that ISP can decide to provision the enterprise ISP. Concretely, that ISP can decide to provision the enterprise
network with: network with:
* The same DOTS server for all network attachments. * The same DOTS server for all network attachments.
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This document does not require any action from IANA. This document does not require any action from IANA.
8. Acknowledgements 8. Acknowledgements
Thanks to Roland Dobbins, Nik Teague, Jon Shallow, Dan Wing, and Thanks to Roland Dobbins, Nik Teague, Jon Shallow, Dan Wing, and
Christian Jacquenet for sharing their comments on the mailing list. Christian Jacquenet for sharing their comments on the mailing list.
Thanks to Kirill Kasavchenko for the comments. Thanks to Kirill Kasavchenko for the comments.
Thanks to Kathleen Moriarty for the secdir review, Joel Jaeggli for Thanks to Kathleen Moriarty for the secdir review, Joel Jaeggli for
the opsdir review, and Mirja Kuhlewind for the tsvart review. 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. Many thanks to Roman Danyliw for the careful AD review.
Thanks to Lars Eggert, Robert Wilton, Paul Wouters, Erik Kline, and Thanks to Lars Eggert, Robert Wilton, Paul Wouters, Erik Kline, and
Eric Vyncke for the IESG review. Eric Vyncke for the IESG review.
9. References 9. References
9.1. Normative References 9.1. 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,
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