Internet Engineering Task Force (IETF)                           R. Bush
Request for Comments: 8893            Internet Initiative Japan & Arrcus
Updates: 6811                                                    R. Volk
Category: Standards Track
ISSN: 2070-1721                                                 J. Heitz
                                                                  Cisco
                                                         September 2020


 Resource Public Key Infrastructure (RPKI) Origin Validation for BGP
                                Export

Abstract

  A BGP speaker may perform Resource Public Key Infrastructure (RPKI)
  origin validation not only on routes received from BGP neighbors and
  routes that are redistributed from other routing protocols, but also
  on routes it sends to BGP neighbors.  For egress policy, it is
  important that the classification use the 'effective origin AS' of
  the processed route, which may specifically be altered by the
  commonly available knobs, such as removing private ASes,
  confederation handling, and other modifications of the origin AS.
  This document updates RFC 6811.

Status of This Memo

  This is an Internet Standards Track document.

  This document is a product of the Internet Engineering Task Force
  (IETF).  It represents the consensus of the IETF community.  It has
  received public review and has been approved for publication by the
  Internet Engineering Steering Group (IESG).  Further information on
  Internet Standards is available in Section 2 of RFC 7841.

  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/rfc8893.

Copyright Notice

  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
  described in the Simplified BSD License.

Table of Contents

  1.  Introduction
  2.  Suggested Reading
  3.  Egress Processing
  4.  Operational Considerations
  5.  Security Considerations
  6.  IANA Considerations
  7.  References
    7.1.  Normative References
    7.2.  Informative References
  Acknowledgments
  Authors' Addresses

1.  Introduction

  This document does not change the protocol or semantics of [RFC6811],
  BGP prefix origin validation.  It highlights an important use case of
  origin validation in external BGP (eBGP) egress policies, explaining
  specifics of correct implementation in this context.

  The term 'effective origin AS' as used in this document refers to the
  Route Origin Autonomous System Number (ASN) [RFC6811] of the UPDATE
  to be sent to neighboring BGP speakers.

  The effective origin AS of a BGP UPDATE is decided by configuration
  and outbound policy of the BGP speaker.  A validating BGP speaker
  MUST apply Route Origin Validation policy semantics (see Section 2 of
  [RFC6811] and Section 4 of [RFC8481]) after applying any egress
  configuration and policy.

  This effective origin AS of the announcement might be affected by
  removal of private ASes, confederation [RFC5065], migration
  [RFC7705], etc.  Any AS_PATH modifications resulting in effective
  origin AS change MUST be taken into account.

  This document updates [RFC6811] by clarifying that implementations
  must use the effective origin AS to determine the Origin Validation
  state when applying egress policy.

  The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
  "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
  "OPTIONAL" in this document are to be interpreted as described in
  BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
  capitals, as shown here.

2.  Suggested Reading

  It is assumed that the reader understands BGP [RFC4271], the RPKI
  [RFC6480], Route Origin Authorizations (ROAs) [RFC6482], RPKI-based
  Prefix Validation [RFC6811], and Origin Validation Clarifications
  [RFC8481].

3.  Egress Processing

  BGP implementations supporting RPKI-based origin validation MUST
  provide the same policy configuration primitives for decisions based
  on the validation state available for use in ingress, redistribution,
  and egress policies.  When applied to egress policy, validation state
  MUST be determined using the effective origin AS of the route as it
  will (or would) be announced to the peer.  The effective origin AS
  may differ from that of the route in the RIB due to commonly
  available knobs, such as removal of private ASes, AS path
  manipulation, confederation handling, etc.

  Egress policy handling can provide more robust protection for
  outbound eBGP than relying solely on ingress (iBGP, eBGP, connected,
  static, etc.) redistribution being configured and working correctly
  -- i.e., better support for the robustness principle.

4.  Operational Considerations

  Configurations may have a complex policy where the effective origin
  AS may not be easily determined before the outbound policies have
  been run.  It SHOULD be possible to specify a selective origin
  validation policy to be applied after any existing non-validating
  outbound policies.

  An implementation SHOULD be able to list announcements that were not
  sent to a peer, e.g., because they were marked Invalid, as long as
  the router still has them in memory.

5.  Security Considerations

  This document does not create security considerations beyond those of
  [RFC6811] and [RFC8481].  By facilitating more correct validation, it
  attempts to improve BGP reliability.

6.  IANA Considerations

  This document has no IANA actions.

7.  References

7.1.  Normative References

  [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119,
             DOI 10.17487/RFC2119, March 1997,
             <https://www.rfc-editor.org/info/rfc2119>.

  [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
             Border Gateway Protocol 4 (BGP-4)", RFC 4271,
             DOI 10.17487/RFC4271, January 2006,
             <https://www.rfc-editor.org/info/rfc4271>.

  [RFC5065]  Traina, P., McPherson, D., and J. Scudder, "Autonomous
             System Confederations for BGP", RFC 5065,
             DOI 10.17487/RFC5065, August 2007,
             <https://www.rfc-editor.org/info/rfc5065>.

  [RFC6482]  Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
             Origin Authorizations (ROAs)", RFC 6482,
             DOI 10.17487/RFC6482, February 2012,
             <https://www.rfc-editor.org/info/rfc6482>.

  [RFC6811]  Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
             Austein, "BGP Prefix Origin Validation", RFC 6811,
             DOI 10.17487/RFC6811, January 2013,
             <https://www.rfc-editor.org/info/rfc6811>.

  [RFC7705]  George, W. and S. Amante, "Autonomous System Migration
             Mechanisms and Their Effects on the BGP AS_PATH
             Attribute", RFC 7705, DOI 10.17487/RFC7705, November 2015,
             <https://www.rfc-editor.org/info/rfc7705>.

  [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
             2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
             May 2017, <https://www.rfc-editor.org/info/rfc8174>.

  [RFC8481]  Bush, R., "Clarifications to BGP Origin Validation Based
             on Resource Public Key Infrastructure (RPKI)", RFC 8481,
             DOI 10.17487/RFC8481, September 2018,
             <https://www.rfc-editor.org/info/rfc8481>.

7.2.  Informative References

  [RFC6480]  Lepinski, M. and S. Kent, "An Infrastructure to Support
             Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
             February 2012, <https://www.rfc-editor.org/info/rfc6480>.

Acknowledgments

  Thanks to reviews and comments from Linda Dunbar, Nick Hilliard,
  Benjamin Kaduk, Chris Morrow, Keyur Patel, Alvaro Retana, Job
  Snijders, Robert Sparks, and Robert Wilton.

Authors' Addresses

  Randy Bush
  Internet Initiative Japan & Arrcus
  5147 Crystal Springs
  Bainbridge Island, WA 98110
  United States of America

  Email: [email protected]


  Rüdiger Volk

  Email: [email protected]


  Jakob Heitz
  Cisco
  170 West Tasman Drive
  San Jose, CA 95134
  United States of America

  Email: [email protected]

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