An improved group-based routing update technique allows limited per
neighbor customization of routing update messages generated by an
interdomain router for its neighboring peer routers within autonomous
systems of a computer network. The technique may be employed when the
neighboring peer routers share identical routing policies, but the
routing update messages differ only in certain attributes with known
locations and lengths. Appropriate values of the location and length
attributes for each neighboring router are calculated and stored during a
replication stage of the improved technique. Before each message is
transmitted, the proper location and length attributes of the message are
updated with the stored values for the respective neighbor.