Link Local Next Hop Handling for BGP
Juniper Networks
Cumulus Networks
Stardust Consulting
VMWare
Apstra, Inc.
Hostinger
BGP, described in [RFC4271], was originally designed to provide reachability between domains and between the edges of a domain. As such, BGP assumes the next hop towards any reachable destination may not reside on the advertising speaker, but rather may either be through a router connected to the same subnet as the speaker, or through a router only reachable by traversing multiple hops through the network. Because of this, BGP does not recognize the use of IPv6 link local addresses, as described in [RFC4291], as a valid next hop for forwarding purposes. However, BGP speakers are now often deployed on point-to-point links in networks where multihop reachability of any kind is not assumed or desired (all next hops are assumed to be the speaker reachable through a directly connected point-to-point link). This is common, for instance, in data center fabrics. In these situations, a global IPv6 address is not required for the advertisement of reachability information; in fact, providing global IPv6 addresses in these kinds of networks can be detrimental to Zero Touch Provisioning (ZTP). This draft standardizes the operation of BGP over a point-to-point link using link local IPv6 addressing only.