17.3. PE-to-CE Network Failures

17.3. PE-to-CE Network Failures

If the connectivity between the multihomed CE and one of the PEs to which it is attached fails, the PE MUST withdraw the set of Ethernet A-D per ES routes that had been previously advertised for that ES. This enables the remote PEs to remove the MPLS next hop to this particular PE from the set of MPLS next hops that can be used to forward traffic to the CE. When the MAC entry on the PE ages out, the PE MUST withdraw the MAC address from BGP.

When an Ethernet tag is decommissioned on an Ethernet segment, then the PE MUST withdraw the Ethernet A-D per EVI route(s) announced for the <ESI, Ethernet tags> that are impacted by the decommissioning. In addition, the PE MUST also withdraw the MAC/IP Advertisement routes that are impacted by the decommissioning.

The Ethernet A-D per ES routes should be used by an implementation to optimize the withdrawal of MAC/IP Advertisement routes. When a PE receives a withdrawal of a particular Ethernet A-D route from an advertising PE, it SHOULD consider all the MAC/IP Advertisement routes that are learned from the same ESI as in the Ethernet A-D route from the advertising PE as having been withdrawn. This optimizes the network convergence times in the event of PE-to-CE failures.