]> Cisco

mdubrovs@cisco.com

General Internet Engineering Task Force Next Hop encoding This document clarifies that the EVPN route Next Hop encoding is unaffected by whether the underlying BGP session is IPv4 or IPv6. From that perspective, this document updates the EVPN specification to provide more comprehensive documentation of the encoding.

Introduction For operational simplicity, a network administrator can choose to enable multiple AFI/SAFI over a single BGP session. While specifies that the Next Hop field of the MP_REACH_NLRI attribute can be set to the IPv4 or IPv6 address for EVPN routes, it does not clarify the exact encoding when the address family of a BGP session does not match the address family of the EVPN Next Hop address. For the sake of interoperability, this document specifies the encoding and therefore, updates . EVPN implementations MUST conform to the prescribed encoding.

Requirements Language 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.

EVPN MP_REACH_NLRI Next Hop encoding EVPN MP_REACH_NLRI can be advertised with either IPv4 or IPv6 next hop. EVPN MP_REACH_NLRI IPv4 Next Hop encoding: EVPN MP_REACH_NLRI IPv4 next Hop encoding

...

Length of Next Hop Address = 4

Network Address of Next Hop = IPv4 address

...

EVPN MP_REACH_NLRI IPv6 next Hop encoding: EVPN MP_REACH_NLRI IPv6 next Hop encoding

...

Length of Next Hop Address = 16

Network Address of Next Hop = IPv6 address

...

The above encoding is done regardless of whether the BGP session is running over IPv4 or IPv6.

IANA Considerations This memo includes no request to IANA.

Security Considerations This document should not affect the security of the Internet.

References Normative References

Acknowledgements The author would like to thank Aamod Vyavaharkar and Kyuhwan Kim for their helpful feedback.