Internet Initiative Japan & Arrcus

5147 Crystal Springs Bainbridge Island WA 98110 United States of America randy@psg.com

ietf@rewvolk.de

Cisco

170 West Tasman Drive San Jose CA 95134 United States of America jheitz@cisco.com

routing security RPKI 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.

Introduction This document does not change the protocol or semantics of , 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) 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 and ) after applying any egress configuration and policy. This effective origin AS of the announcement might be affected by removal of private ASes, confederation , migration , etc. Any AS_PATH modifications resulting in effective origin AS change MUST be taken into account. This document updates 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 when, and only when, they appear in all capitals, as shown here.

Suggested Reading It is assumed that the reader understands BGP , the RPKI , Route Origin Authorizations (ROAs) , RPKI-based Prefix Validation , and Origin Validation Clarifications .

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.

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.

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

IANA Considerations This document has no IANA actions.

References Normative References Informative References

Acknowledgments Thanks to reviews and comments from , , , , , , , , and .