RPKI BGP export: Resource Public Key Infrastructure (RPKI) Origin Validation for BGP Export
Check route origins on the routes a BGP router sends out, using the origin AS that will actually be announced.
Bush, R., Volk, R., and J. Heitz, "Resource Public Key Infrastructure (RPKI) Origin Validation for BGP Export", RFC 8893, DOI 10.17487/RFC8893, September 2020, <https://www.rfc-editor.org/info/rfc8893>.
@misc{rfc8893,
series = {Request for Comments},
number = 8893,
howpublished = {RFC 8893},
publisher = {RFC Editor},
doi = {10.17487/RFC8893},
url = {https://www.rfc-editor.org/info/rfc8893},
author = {R. Bush and R. Volk and J. Heitz},
title = {{Resource Public Key Infrastructure (RPKI) Origin Validation for BGP Export}},
pagetotal = 5,
year = 2020,
month = sep,
} RFC text
Contents
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: randy@psg.com
Rüdiger Volk
Email: ietf@rewvolk.de
Jakob Heitz
Cisco
170 West Tasman Drive
San Jose, CA 95134
United States of America
Email: jheitz@cisco.com
AI ELI5
On this page
§1Outbound Origin Validation
This document does not change the protocol or semantics of RFC 6811, BGP prefix origin validation. It highlights an important use case: origin validation in external BGP (eBGP) egress policies, and how to implement it correctly there.
It updates RFC 6811 by clarifying that implementations must use the effective origin AS to determine the Origin Validation state when applying egress policy.
Routers already check where announcements come from when they arrive. This note says they can check the ones they send out, too.
§1The Effective Origin AS
The effective origin AS is the Route Origin ASN of the UPDATE that will be sent to neighboring BGP speakers. It is decided by the configuration and outbound policy of the speaker, so it can differ from the origin of the route stored in the RIB.
Removal of private ASes, confederation, migration and other AS_PATH modifications can change it. A validating BGP speaker MUST apply Route Origin Validation policy semantics after applying any egress configuration and policy, and any AS_PATH modification that changes the effective origin AS MUST be taken into account.
The name on the envelope is what counts, not the name in the filing cabinet. If the name gets changed on the way out, check the new one.
§3Egress Processing
BGP implementations that support RPKI-based origin validation MUST provide the same policy configuration primitives for decisions based on validation state in ingress, redistribution and egress policies. In 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 RFC says egress handling can protect outbound eBGP more robustly than relying only on ingress or redistribution being configured and working correctly, which supports the robustness principle.
A router gets the same set of checking tools for incoming, passed-along and outgoing routes. For outgoing ones it checks the name that will really be sent.
§4Operational Considerations
Policies can be complex, and the effective origin AS may not be easy to determine until the outbound policies have run. It SHOULD be possible to specify a selective origin validation policy that is applied after any existing non-validating outbound policies.
An implementation SHOULD be able to list announcements that were not sent to a peer, for example because they were marked Invalid, as long as the router still has them in memory.
Do the checking last, after the other changes are done. And keep a list of what was held back, so people can see what happened.