Loop avoidance and egress link protection with ethernet virtual private network (evpn) fast reroute (frr)

Abstract

The problem of looping at the egress of a transport network with a CE multihomed to a protected egress PE and a backup/protector egress PE can be avoided by (a) enabling the protector egress PE to distinguish between fast reroute (FRR) traffic coming from the protected egress PE and normal known unicast (KU) traffic coming from a PE of the transport network that is not attached to the same multihomed segment; (b) receiving, by the protector egress PE, known unicast data, to be forwarded to the CE; (c) determining, by the protector egress PE, that a link between it and the CE is unavailable; and (d) responsive to determining that the link between the protector egress PE and the CE is unavailable, (1) determining whether the known unicast traffic received was sent from the protected egress PE or from another PE of the transport network that is not attached to the same multihomed segment, and (2) responsive to a determination that the known unicast traffic received was sent from the protected egress PE, discarding the known unicast traffic received, and otherwise, responsive to a determination that the known unicast (KU) traffic received was sent from another PE of the transport network that is not attached to the same multihomed segment, sending the known unicast traffic, via a backup tunnel, to an egress PE which protects the protector egress PE.