IETF RFC 8950 PDF

Abstract

Multiprotocol BGP (MP-BGP) specifies that the set of usable next-hop address families is determined by the Address Family Identifier (AFI) and the Subsequent Address Family Identifier (SAFI). The AFI/SAFI definitions for the IPv4 address family only have provisions for advertising a next-hop address that belongs to the IPv4 protocol when advertising IPv4 Network Layer Reachability Information (NLRI) or VPN-IPv4 NLRI.

This document specifies the extensions necessary to allow the advertising of IPv4 NLRI or VPNI-Pv4 NLRI with a next-hop address that belongs to the IPv6 protocol. This comprises an extension of the AFI/SAFI definitions to allow the address of the next hop for IPv4 NLRI or VPN-IPv4 NLRI to also belong to the IPv6 protocol, the encoding of the next hop to determine which of the protocols the address actually belongs to, and a BGP Capability allowing MP-BGP peers to dynamically discover whether they can exchange IPv4 NLRI and VPN-IPv4 NLRI with an IPv6 next hop. This document obsoletes RFC 5549.