EVPN multihoming is supported with PBB-EVPN Epipes, but only in a limited number of scenarios. In general, the following applies to PBB-EVPN Epipes:
PBB-EVPN Epipes do not support spoke SDPs that are associated with EVPN ESs.
PBB-EVPN Epipes support all-active EVPN multihoming as long as no local-switching is required in the Epipe instance where the ES is defined.
PBB-EVPN Epipes support single-active EVPN multihoming only in a two-node case scenario.
Figure: PBB-EVPN MH in a three-node scenario shows the EVPN MH support in a three-node scenario.
EVPN MH support in a three-node scenario has the following characteristics:
All-active EVPN multihoming is fully supported (diagram on the left in Figure: PBB-EVPN MH in a three-node scenario). CE1 may also be multihomed to other PEs, as long as those PEs are not PE2 or PE3. In this case, PE1 Epipe's pbb-tunnel would be configured with the remote ES B-MAC.
Single-active EVPN multihoming is not supported in a three (or more)-node scenario (diagram on the right in Figure: PBB-EVPN MH in a three-node scenario). Because PE1's Epipe pbb-tunnel can only point at a single remote B-MAC and single-active multihoming requires the use of separate B-MACs on PE2 and PE3, the scenario is not possible and not supported regardless of the ES association to port/LAG/sdps.
Regardless of the EVPN multihoming type, the CLI prevents the user from adding a spoke SDP to an Epipe, if the corresponding SDP is part of an ES.
Figure: PBB-EVPN MH in a two-node scenario shows the EVPN MH support in a two-node scenario.
EVPN MH support in a two-node scenario has the following characteristics, as shown in Figure: PBB-EVPN MH in a two-node scenario:
All-active multihoming is not supported for redundancy in this scenario because PE1's pbb-tunnel cannot point at a locally defined ES B-MAC. This is represented in the left-most scenario in Figure: PBB-EVPN MH in a two-node scenario.
Single-active multihoming is supported for redundancy in a two-node three or four SAP scenario, as displayed by the two right-most scenarios in Figure: PBB-EVPN MH in a two-node scenario).
In these two cases, the Epipe pbb-tunnel is configured with the source B-MAC of the remote PE node.
When two SAPs are active in the same Epipe, local-switching is used to exchange frames between the CEs.