Patent ID: 7957306

Claim:
An apparatus for providing reachability information in a routing domain of a data communications network having as components nodes and links therebetween for a routing domain external destination address, the apparatus comprising: a processor; and a computer-readable volatile or non-volatile storage medium comprising one or more stored sequences of instructions causing the processor to perform: advertising, internally to nodes in a routing domain of a first autonomous system, whether two or more diverse external connections are available from the apparatus of the first autonomous system to a routing domain external destination address of a second autonomous system; and associating a reachability category, indicating a level of redundancy available in the two or more diverse external connections from the apparatus of the first autonomous system to the routing domain external destination address of the second autonomous system, with said internal advertisements of said two or more diverse external connections; wherein the level of redundancy indicates both availability and quality of each of the two or more diverse external connections, and whether parallel external connections are available from the first autonomous system to the routing domain external destination address of the second autonomous system at the time of the advertising.