ESI failures are resolved depending on the B-MAC address assignment chosen by the user:
If the B-MAC address assignment is based on the use of es-bmacs, DF and non-DFs do send the es-bmac/ESI=0 for a specified ESI. Each PE has a different es-bmac for the same ESI (as opposed to the same es-bmac on all the PEs for all-active).
In case of an ESI failure, the PE withdraws its es-bmac route triggering a mac-flush of all the C-MACs associated with it in the remote PEs.
If the B-MAC address assignment is based on the use of source-bmac, DF and non-DFs advertise their respective source-bmacs. In case of an ES failure:
The PE re-advertises its source-bmac with a higher sequence number (the new DF does not re-advertise its source-bmac).
The far-end PEs interpret a source-bmac advertisement with a different sequence number as a flush-all-from-me message from the PE detecting the failure. They flush all the C-MACs associated with that B-MAC in all the ISID services.
The following events trigger a C-MAC flush notification. A 'C-MAC flush notification' means the withdrawal of a specified B-MAC or the update of B-MAC with a higher sequence number (SQN). Both BGP messages make the remote PEs flush all the C-MACs associated with the indicated B-MAC:
B-VPLS transition to operationally down status. This triggers the withdrawal of the associated B-MACs, regardless of the use-es-bmac setting.
Change of pbb>source-bmac. This triggers the withdrawal and re-advertisement of the source-bmac, causing the corresponding C-MAC flush in the remote PEs.
Change of es-bmac (removal of pbb use-es-bmac). This triggers the withdrawal of the es-bmac and re-advertisement of the new es-bmac.
Ethernet-Segment (ES) transition to operationally down or admin-down status. This triggers an es-bmac withdrawal (if use-es-bmac is used) or an update of the source-bmac with a higher SQN (if no use-es-bmac is used).
Service Carving Range change for the ES. This triggers an es-bmac update with higher SQN (if use-es-bmac is used) or an update of the source-bmac with a higher SQN (if no use-es-bmac is used).
Change in the number of candidate PEs for the ES. This triggers an es-bmac update with higher SQN (if use-es-bmac is used) or an update of the source-bmac with a higher SQN (if no use-es-bmac is used).
In an ESI, individual SAPs/SDP bindings or individual I-VPLS going operationally down 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.