This feature minimizes the downtime for PPPoE clients in an ESM environment when a single node fails.
It is not necessary that an entire BNG fails before it triggers the corrective action. The solution described in this section includes protection against interfaces and line card failures within the BNG. The redundant (protective) entity, however, does not reside within the same BNG on which the failure occurs but instead it is on a separate BNG node.
The PPPoE MC Redundancy is based on SRRP and MC-LAG because SRRP is already established in ESM providing IPoE MC Redundancy. With some modifications, SRRP approach is adopted to PPPoE deployments.