PBB-EVPN multihoming in I-VPLS and PBB Epipe services

The 7750 SR, 7450 ESS, and 7950 XRS SR OS PBB-EVPN implementation supports all-active and single-active multihoming for I-VPLS and PBB Epipe services.

PBB-EVPN multihoming reuses the ethernet-segment concept described in section EVPN multihoming in VPLS services. However, unlike EVPN-MPLS, PBB-EVPN does not use AD routes; it uses B-MACs for split-horizon checks and aliasing.