Domain Path (D-PATH) for Ethernet VPN (EVPN) Interconnect Networks

The BGP Domain PATH (D-PATH) attribute is defined for Inter-Subnet Forwarding (ISF) BGP Sub-Address Families that advertise IP prefixes. When used along with EVPN IP Prefix routes or IP-VPN routes, it identifies the domain(s) through which the routes have passed and that information can be used by the receiver BGP speakers to detect routing loops or influence the BGP best path selection. This document extends the use of D-PATH so that it can also be used along with other EVPN route types.