Egress leaf node failure behavior in Anycast ES

Anycast VTEPs ensure node failure events are handled smoothly and efficiently. The following diagram shows the situation before the node failure (left) and after (right).

Figure 1. Egress leaf node failure behavior in Anycast ESes
Note:

The following behavior assumes that Leaf3 keeps at least one MAC/IP route for Server-1 and ESI-1 after the node failure. Otherwise, the MAC is flushed, and unknown unicast traffic is flooded.

  • Non-failure state: The ES destination on Leaf3 points to the Anycast VTEP IP address 12.12.12.12. Per flow load balancing occurs based on the underlay set to 12.12.12.12 without using overlay ECPM sets.
  • Egress leaf failure (such as when Leaf1 goes down): In-flight packets are immediately rerouted to Leaf2, which also advertises the Anycast VTEP address. When Leaf3 receives the A-D per-ES MP_NLRI_UNREACH message from Leaf1, Leaf3 reprograms the ES destination to use the unicast VTEP of Leaf2, as specified by the AD per-ES route of the surviving ES leaf, Leaf2.