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 1 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 1). 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 1). 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 2 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 2:
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 2.
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 2).
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.