Figure: EVPN for PBB over MPLS shows the use of EVPN for MPLS tunnels on the 7750 SR, 7450 ESS, and 7950 XRS. In this case, EVPN is used as the control plane for E-LAN services in the WAN.
EVPN for PBB over MPLS (hereafter called PBB-EVPN) is specified in RFC 7623. It provides a simplified version of EVPN for cases where the network requires very high scalability and does not need all the advanced features supported by EVPN-MPLS (but still requires single-active and all-active multihoming capabilities).
PBB-EVPN is a combination of 802.1ah PBB and RFC 7432 EVPN and reuses the PBB-VPLS service model, where BGP-EVPN is enabled in the B-VPLS domain. EVPN is used as the control plane in the B-VPLS domain to control the distribution of B-MACs and setup per-ISID flooding trees for I-VPLS services. The learning of the C-MACs, either on local SAPs/SDP bindings or associated with remote B-MACs, is still performed in the data plane. Only the learning of B-MACs in the B-VPLS is performed through BGP.
The SR OS PBB-EVPN implementation supports PBB-EVPN for I-VPLS and PBB-Epipe services, including single-active and all-active multihoming.