A local fast reroute (FRR) technique is implemented at the edge of a
computer network. In accordance with the technique, if an edge device
detects a node or link failure that prevents it from communicating with a
neighboring routing domain, the edge device reroutes at least some data
packets addressed to that domain to a backup edge device which, in turn,
forwards the packets to the neighboring domain. The rerouted packets are
designated as being "protected" (i.e., rerouted) data packets before they
are forwarded to the backup edge device. The backup edge device
identifies protected data packets as those which contain a predetermined
"service" label in their MPLS label stacks. In other words, the service
label is used as an identifier for packets that have been FRR rerouted.
Upon receiving a data packet containing a service label, the backup edge
device is not permitted to reroute the packet a second time, e.g., in
response to another inter-domain node or link failure, thereby preventing
loops from developing at the edge of the network.