--- 1/draft-ietf-grow-route-leak-detection-mitigation-01.txt 2020-01-25 21:13:09.329080165 -0800 +++ 2/draft-ietf-grow-route-leak-detection-mitigation-02.txt 2020-01-25 21:13:09.353080780 -0800 @@ -1,19 +1,19 @@ IDR and SIDR K. Sriram, Ed. Internet-Draft USA NIST Intended status: Standards Track A. Azimov, Ed. -Expires: January 26, 2020 Yandex - July 25, 2019 +Expires: July 28, 2020 Yandex + January 25, 2020 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 Problem definition for route leaks and enumeration of types of route leaks are provided in [RFC7908]. This document describes a new well- known Large Community that provides a way for route leak prevention, detection, and mitigation. The configuration process for this Community can be automated with the methodology for setting BGP roles that is described in ietf-idr-bgp-open-policy draft. @@ -25,25 +25,25 @@ 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 and may be updated, replaced, or obsoleted by other documents 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 January 26, 2020. + This Internet-Draft will expire on July 28, 2020. 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. 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 BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as @@ -51,22 +51,22 @@ Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Peering Relationships . . . . . . . . . . . . . . . . . . . . 2 3. Community vs Attribute . . . . . . . . . . . . . . . . . . . 3 4. Down Only Community . . . . . . . . . . . . . . . . . . . . . 4 4.1. Route Leak Mitigation . . . . . . . . . . . . . . . . . . 5 4.2. Only Marking . . . . . . . . . . . . . . . . . . . . . . 6 5. Implementation Considerations . . . . . . . . . . . . . . . . 6 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 8. Informative References . . . . . . . . . . . . . . . . . . . 7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction [RFC7908] provides a definition of the route leak problem and enumerates several types of route leaks. For this document, the definition that is applied is that a route leak occurs when a route @@ -123,23 +123,24 @@ 3. Community vs Attribute This section presents a brief discussion of the advantages and disadvantages of communities and BGP path attributes for the purpose of route leak detection. A transitive path attribute is a native way to implement the route- leak detection signal. Based on the way BGP protocol works, the use of a transitive attribute makes it more certain that the route-leak 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 - 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. The potential disadvantage of using a Community for the route-leak 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 is somewhat overloaded. BGP Communities are already used for numerous applications: different types of route marking, route policy control, black-holing, etc. It is observed that some ASes seem to purposefully or accidentally remove transitive communities on receipt, sometimes well-known ones. Perhaps this issue may be @@ -148,39 +149,39 @@ Due to frequently occurring regional and global disruptions in Internet connectivity, it is critical to move forward with a solution that is viable in the near term. That solution would be route leak detection using BGP Community. Large Communities have much higher capacity, and therefore they are likely to be less overloaded. Hence, Large Community is proposed to be used for route-leak detection. This document suggests reserving 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 signal described here can also be carried in a BGP path attribute, and the same prevention and mitigation techniques as described here would apply. The authors are pursuing a separate internet draft in the IDR WG on that approach. 4. Down Only Community This section specifies the semantics of route-leak-detection Community and its usage. This Community is given the specific name Down Only (DO) Community. The DO Community is carried in a BGP Large Community with a format as 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | TBD1 (class for well-known transit communities) | + | TBD1 (class for transitive well-known Large Communities) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TBD2 (subclass for DO) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ASN | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Format of the DO Community using a Large Community [RFC8092]. The authors studied different options for route leak mitigation. The @@ -222,21 +223,21 @@ 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 halts. 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 neighbor's ASN. 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. 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. The above procedures comprehensively provide route-leak prevention, detection and mitigation. Policy consisting of these procedures SHOULD be used as a default behavior. 4.2. Only Marking @@ -286,53 +287,53 @@ 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, otherwise it is a route leak. The procedure halts. This rule is based on a weaker assumption that a peer that is doing marking is also doing filtering (dropping detected leaks). That is why networks that do not follow the route leak mitigation policy in Section 4.1 MUST carefully follow marking rules described in Section 4.2. -6. Security Considerations +6. IANA Considerations + + The draft suggests to reserve a Global Administrator ID for + transitive well-known Large Community registry. IANA is requested to + register a subclass for DO Community in this registry. + +7. Security Considerations In specific circumstances in a state of partial adoption, route leak mitigation mechanism can result in Denial of Service (DoS) for the 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 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 injected somewhere inside this single path, then it may be rejected by upper layer providers in the path, thus limiting prefix visibility. While such anomaly is unlikely to happen, such an issue should be easy to debug, since it directly affects the sequence of originator's providers. With the use of BGP Community, there is often a concern that the Community propagates beyond its intended perimeter and causes harm [streibelt]. However, that concern does not apply to the DO Community because it is a transitive Community that must propagate as far as the update goes. -7. IANA Considerations - - The draft suggests to reserve a Global Administrator ID for - transitive well-known Large Community registry. IANA is requested to - register a subclass for DO Community in this registry. - 8. Informative References [I-D.ietf-idr-bgp-open-policy] Azimov, A., Bogomazov, E., Bush, R., Patel, K., and K. Sriram, "Route Leak Prevention using Roles in Update and - Open messages", draft-ietf-idr-bgp-open-policy-06 (work in - progress), July 2019. + Open messages", draft-ietf-idr-bgp-open-policy-07 (work in + progress), January 2020. [RFC4264] Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264, DOI 10.17487/RFC4264, November 2005, . [RFC7908] Sriram, K., Montgomery, D., McPherson, D., Osterweil, E., and B. Dickson, "Problem Definition and Classification of BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June 2016, . @@ -342,21 +343,21 @@ . [streibelt] Streibelt et al., F., "BGP Communities: Even more Worms in the Routing Can", ACM IMC, October 2018, . Acknowledgements 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 The following people made significant contributions to this document and should be considered co-authors: Brian Dickson Independent Email: brian.peter.dickson@gmail.com