Extension to BGP

[RFC2918] defines a route refresh capability to be exchanged between BGP speakers. BGP speakers that support this capability are advertising that they can resend the entire BGP Adj-RIB-Out on receipt of a refresh request. By supporting this capability, BGP speakers are more flexible in applying any inbound routing policy changes as they no longer have to store received routes in their unchanged form or reset the session when an inbound routing policy change occurs. The route refresh capability is advertised per AFI, SAFI combination. There are newer AFI, SAFI types that have been introduced to BGP that support a variety of route types (e.g. IPv4/MVPN, L2VPN/EVPN). Currently, there is no way to request a subset of routes in a Route Refresh message for a given AFI, SAFI. This draft defines route refresh capability extensions that help BGP speakers to request a subset of routes for a given address family. This is expected to reduce the amount of update traffic being generated by route refresh requests as well as lessen the burden on the router servicing such requests.