Network failures and convergence for all-active multihoming

ES failures are resolved by the PEs withdrawing the es-bmac. The remote PEs withdraw the route and update their list of next-hops for a specified es-bmac.

No mac-flush of the I-VPLS FDB tables is required as long as the es-bmac is still in the FDB.

When the route corresponding to the last next-hop for a specified es-bmac is withdrawn, the es-bmac is flushed from the B-VPLS FDB and all the C-MACs associated with it are flushed too.

The following events trigger a withdrawal of the es-bmac and the corresponding next-hop update in the remote PEs:

B-VPLS transition to operationally down status.
Change of pbb>source-bmac.
Change of es-bmac (or removal of pbb use-es-bmac).
Ethernet-segment transition to operationally down status.

Note: Individual SAPs going operationally down in an ES do not generate any BGP withdrawal or indication so that the remote nodes can flush their C-MACs. This is solved in EVPN-MPLS by the use of AD routes per EVI; however, there is nothing similar in PBB-EVPN for indicating a partial failure in an ESI.