Patent ID: 7283467

Claim:
A method of routing connections through a data communications network having nodes arranged in a routing hierarchy of respective peer groups, in which a connection is routed between an originating node and a destination node in the hierarchy and a path for the connection, on set up, includes an entry border node in a peer group to which the destination node belongs, a failure to complete a connection between the entry node and the destination node having been detected, the method comprising the steps of: a) determining whether the entry border node has detected any link blocked crankback message with a succeeding null node ID for the connection, b) if a link blocked crankback message with a succeeding null node ID for the connection has not been detected, initiating by the entry border node a crankback message to a preceding routing-capable node in the path indicating that the link into the peer group is blocked; and c) attempting, at the preceding routing-capable node to route the connection to the peer group over another link.