draft-ietf-grow-route-leak-detection-mitigation-01.txt   draft-ietf-grow-route-leak-detection-mitigation-02.txt 
IDR and SIDR K. Sriram, Ed. IDR and SIDR K. Sriram, Ed.
Internet-Draft USA NIST Internet-Draft USA NIST
Intended status: Standards Track A. Azimov, Ed. Intended status: Standards Track A. Azimov, Ed.
Expires: January 26, 2020 Yandex Expires: July 28, 2020 Yandex
July 25, 2019 January 25, 2020
Methods for Detection and Mitigation of BGP Route Leaks Methods for Detection and Mitigation of BGP Route Leaks
draft-ietf-grow-route-leak-detection-mitigation-01 draft-ietf-grow-route-leak-detection-mitigation-02
Abstract Abstract
Problem definition for route leaks and enumeration of types of route Problem definition for route leaks and enumeration of types of route
leaks are provided in [RFC7908]. This document describes a new well- leaks are provided in [RFC7908]. This document describes a new well-
known Large Community that provides a way for route leak prevention, known Large Community that provides a way for route leak prevention,
detection, and mitigation. The configuration process for this detection, and mitigation. The configuration process for this
Community can be automated with the methodology for setting BGP roles Community can be automated with the methodology for setting BGP roles
that is described in ietf-idr-bgp-open-policy draft. that is described in ietf-idr-bgp-open-policy draft.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 26, 2020. This Internet-Draft will expire on July 28, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2020 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 Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Peering Relationships . . . . . . . . . . . . . . . . . . . . 2 2. Peering Relationships . . . . . . . . . . . . . . . . . . . . 2
3. Community vs Attribute . . . . . . . . . . . . . . . . . . . 3 3. Community vs Attribute . . . . . . . . . . . . . . . . . . . 3
4. Down Only Community . . . . . . . . . . . . . . . . . . . . . 4 4. Down Only Community . . . . . . . . . . . . . . . . . . . . . 4
4.1. Route Leak Mitigation . . . . . . . . . . . . . . . . . . 5 4.1. Route Leak Mitigation . . . . . . . . . . . . . . . . . . 5
4.2. Only Marking . . . . . . . . . . . . . . . . . . . . . . 6 4.2. Only Marking . . . . . . . . . . . . . . . . . . . . . . 6
5. Implementation Considerations . . . . . . . . . . . . . . . . 6 5. Implementation Considerations . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Informative References . . . . . . . . . . . . . . . . . . . 7 8. Informative References . . . . . . . . . . . . . . . . . . . 7
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
[RFC7908] provides a definition of the route leak problem and [RFC7908] provides a definition of the route leak problem and
enumerates several types of route leaks. For this document, the enumerates several types of route leaks. For this document, the
definition that is applied is that a route leak occurs when a route definition that is applied is that a route leak occurs when a route
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3. Community vs Attribute 3. Community vs Attribute
This section presents a brief discussion of the advantages and This section presents a brief discussion of the advantages and
disadvantages of communities and BGP path attributes for the purpose disadvantages of communities and BGP path attributes for the purpose
of route leak detection. of route leak detection.
A transitive path attribute is a native way to implement the route- A transitive path attribute is a native way to implement the route-
leak detection signal. Based on the way BGP protocol works, the use leak detection signal. Based on the way BGP protocol works, the use
of a transitive attribute makes it more certain that the route-leak of a transitive attribute makes it more certain that the route-leak
detection signal would pass unaltered through non-participating detection signal would pass unaltered through non-participating
(i.e., not updated) BGP routers. The main disadvantage of this (i.e., not upgraded) BGP routers. The main disadvantage of this
approach is that the deployment of a new BGP attribute requires a approach is that the deployment of a new BGP attribute requires a
software update in router OS which may delay wide adoption for years. software upgrade in router OS which may delay wide adoption for
years.
On the other hand, BGP communities do not require a router OS update. On the other hand, BGP communities do not require a router OS update.
The potential disadvantage of using a Community for the route-leak The potential disadvantage of using a Community for the route-leak
detection signal is that it is more likely to be dropped somewhere detection signal is that it is more likely to be dropped somewhere
along the way in the AS path. Currently, the use of BGP Communities along the way in the AS path. Currently, the use of BGP Communities
is somewhat overloaded. BGP Communities are already used for is somewhat overloaded. BGP Communities are already used for
numerous applications: different types of route marking, route policy numerous applications: different types of route marking, route policy
control, black-holing, etc. It is observed that some ASes seem to control, black-holing, etc. It is observed that some ASes seem to
purposefully or accidentally remove transitive communities on purposefully or accidentally remove transitive communities on
receipt, sometimes well-known ones. Perhaps this issue may be receipt, sometimes well-known ones. Perhaps this issue may be
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Due to frequently occurring regional and global disruptions in Due to frequently occurring regional and global disruptions in
Internet connectivity, it is critical to move forward with a solution Internet connectivity, it is critical to move forward with a solution
that is viable in the near term. That solution would be route leak that is viable in the near term. That solution would be route leak
detection using BGP Community. detection using BGP Community.
Large Communities have much higher capacity, and therefore they are Large Communities have much higher capacity, and therefore they are
likely to be less overloaded. Hence, Large Community is proposed to likely to be less overloaded. Hence, Large Community is proposed to
be used for route-leak detection. This document suggests reserving be used for route-leak detection. This document suggests reserving
<TBD1> class for the purpose of transitive well-known Large <TBD1> class for the purpose of transitive well-known Large
Communities that MUST not be stripped on ingress or egress. Communities that MUST NOT be stripped on ingress or egress.
While it is not part of this document, the route-leak detection While it is not part of this document, the route-leak detection
signal described here can also be carried in a BGP path attribute, signal described here can also be carried in a BGP path attribute,
and the same prevention and mitigation techniques as described here and the same prevention and mitigation techniques as described here
would apply. The authors are pursuing a separate internet draft in would apply. The authors are pursuing a separate internet draft in
the IDR WG on that approach. the IDR WG on that approach.
4. Down Only Community 4. Down Only Community
This section specifies the semantics of route-leak-detection This section specifies the semantics of route-leak-detection
Community and its usage. This Community is given the specific name Community and its usage. This Community is given the specific name
Down Only (DO) Community. The DO Community is carried in a BGP Large Down Only (DO) Community. The DO Community is carried in a BGP Large
Community with a format as shown in Figure 1. Community with a format as shown in Figure 1.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBD1 (class for well-known transit communities) | | TBD1 (class for transitive well-known Large Communities) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBD2 (subclass for DO) | | TBD2 (subclass for DO) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ASN | | ASN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Format of the DO Community using a Large Community Figure 1: Format of the DO Community using a Large Community
[RFC8092]. [RFC8092].
The authors studied different options for route leak mitigation. The The authors studied different options for route leak mitigation. The
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transit) and DO value is not equal to the sending neighbor's ASN, transit) and DO value is not equal to the sending neighbor's ASN,
then it is a route leak and MUST be rejected. The procedure then it is a route leak and MUST be rejected. The procedure
halts. halts.
3. If a route is received from a Provider, Peer or RS, then the DO 3. If a route is received from a Provider, Peer or RS, then the DO
Community MUST be added with a value equal to the sending Community MUST be added with a value equal to the sending
neighbor's ASN. neighbor's ASN.
The egress policy MUST use the following procedure: The egress policy MUST use the following procedure:
1. A route with DO Community set MUST not be sent to Providers, 1. A route with DO Community set MUST NOT be sent to Providers,
Peers, and RS. Peers, and RS.
2. If a route is sent to a Customer or Peer, then the DO Community 2. If a route is sent to a Customer or Peer, then the DO Community
MUST be added with a value equal to the ASN of the sender. MUST be added with a value equal to the ASN of the sender.
The above procedures comprehensively provide route-leak prevention, The above procedures comprehensively provide route-leak prevention,
detection and mitigation. Policy consisting of these procedures detection and mitigation. Policy consisting of these procedures
SHOULD be used as a default behavior. SHOULD be used as a default behavior.
4.2. Only Marking 4.2. Only Marking
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If a route with DO Community set is received from a Peer and DO value If a route with DO Community set is received from a Peer and DO value
is equal to the sending neighbor's ASN, then it is a valid route, is equal to the sending neighbor's ASN, then it is a valid route,
otherwise it is a route leak. The procedure halts. otherwise it is a route leak. The procedure halts.
This rule is based on a weaker assumption that a peer that is doing This rule is based on a weaker assumption that a peer that is doing
marking is also doing filtering (dropping detected leaks). That is marking is also doing filtering (dropping detected leaks). That is
why networks that do not follow the route leak mitigation policy in why networks that do not follow the route leak mitigation policy in
Section 4.1 MUST carefully follow marking rules described in Section 4.1 MUST carefully follow marking rules described in
Section 4.2. Section 4.2.
6. Security Considerations 6. IANA Considerations
The draft suggests to reserve a Global Administrator ID <TBD1> for
transitive well-known Large Community registry. IANA is requested to
register a subclass <TBD2> for DO Community in this registry.
7. Security Considerations
In specific circumstances in a state of partial adoption, route leak In specific circumstances in a state of partial adoption, route leak
mitigation mechanism can result in Denial of Service (DoS) for the mitigation mechanism can result in Denial of Service (DoS) for the
victim prefix. Such a scenario may happen only for a prefix that has victim prefix. Such a scenario may happen only for a prefix that has
a single path from the originator to a Tier-1 ISP and only when the a single path from the originator to a Tier-1 ISP and only when the
prefix is not covered with a less specific prefix with multiple paths prefix is not covered with a less specific prefix with multiple paths
to the Tier-1 ISP. If, in such unreliable topology, route leak is to the Tier-1 ISP. If, in such unreliable topology, route leak is
injected somewhere inside this single path, then it may be rejected injected somewhere inside this single path, then it may be rejected
by upper layer providers in the path, thus limiting prefix by upper layer providers in the path, thus limiting prefix
visibility. While such anomaly is unlikely to happen, such an issue visibility. While such anomaly is unlikely to happen, such an issue
should be easy to debug, since it directly affects the sequence of should be easy to debug, since it directly affects the sequence of
originator's providers. originator's providers.
With the use of BGP Community, there is often a concern that the With the use of BGP Community, there is often a concern that the
Community propagates beyond its intended perimeter and causes harm Community propagates beyond its intended perimeter and causes harm
[streibelt]. However, that concern does not apply to the DO [streibelt]. However, that concern does not apply to the DO
Community because it is a transitive Community that must propagate as Community because it is a transitive Community that must propagate as
far as the update goes. far as the update goes.
7. IANA Considerations
The draft suggests to reserve a Global Administrator ID <TBD1> for
transitive well-known Large Community registry. IANA is requested to
register a subclass <TBD2> for DO Community in this registry.
8. Informative References 8. Informative References
[I-D.ietf-idr-bgp-open-policy] [I-D.ietf-idr-bgp-open-policy]
Azimov, A., Bogomazov, E., Bush, R., Patel, K., and K. Azimov, A., Bogomazov, E., Bush, R., Patel, K., and K.
Sriram, "Route Leak Prevention using Roles in Update and Sriram, "Route Leak Prevention using Roles in Update and
Open messages", draft-ietf-idr-bgp-open-policy-06 (work in Open messages", draft-ietf-idr-bgp-open-policy-07 (work in
progress), July 2019. progress), January 2020.
[RFC4264] Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264, [RFC4264] Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264,
DOI 10.17487/RFC4264, November 2005, DOI 10.17487/RFC4264, November 2005,
<https://www.rfc-editor.org/info/rfc4264>. <https://www.rfc-editor.org/info/rfc4264>.
[RFC7908] Sriram, K., Montgomery, D., McPherson, D., Osterweil, E., [RFC7908] Sriram, K., Montgomery, D., McPherson, D., Osterweil, E.,
and B. Dickson, "Problem Definition and Classification of and B. Dickson, "Problem Definition and Classification of
BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June
2016, <https://www.rfc-editor.org/info/rfc7908>. 2016, <https://www.rfc-editor.org/info/rfc7908>.
skipping to change at page 8, line 23 skipping to change at page 8, line 23
<https://www.rfc-editor.org/info/rfc8092>. <https://www.rfc-editor.org/info/rfc8092>.
[streibelt] [streibelt]
Streibelt et al., F., "BGP Communities: Even more Worms in Streibelt et al., F., "BGP Communities: Even more Worms in
the Routing Can", ACM IMC, October 2018, the Routing Can", ACM IMC, October 2018,
<https://archive.psg.com//181101.imc-communities.pdf>. <https://archive.psg.com//181101.imc-communities.pdf>.
Acknowledgements Acknowledgements
The authors wish to thank John Scudder, Susan Hares, Ruediger Volk, The authors wish to thank John Scudder, Susan Hares, Ruediger Volk,
Mat Ford, Greg Skinner for their review and comments. Jeffrey Haas, Mat Ford, Greg Skinner for their review and comments.
Contributors Contributors
The following people made significant contributions to this document The following people made significant contributions to this document
and should be considered co-authors: and should be considered co-authors:
Brian Dickson Brian Dickson
Independent Independent
Email: brian.peter.dickson@gmail.com Email: brian.peter.dickson@gmail.com
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