Patent ID: 6560218
Filing Date: 2003-05-06
Classification: H04L,H04Q

Abstract:
A method of establishing a call in a virtual circuit based communications network comprising a plurality of network nodes and employing hop-by-hop routing, each network node having a preconfigured routing table which contains next hop information to adjacent nodes for routes leading to endpoints of the network, comprising the steps of:preconfiguring in said routing table of each individual network node next hop information associated respectively with a primary route and an alternate route to respective network endpoints; sending a setup message having a destination endpoint for said call through said network; receiving said setup message at a network node, said network node on receipt of said setup message searching its routing table based on the destination endpoint for corresponding next hop information identifying the next node on the primary route to the destination endpoint; said network node attempting to forward the setup message on the primary route defined in the corresponding next hop information retrieved from said routing table for the primary route for said network node; and if the primary route is not usable, said network node ten attempting to forward the setup message on the alternate route defined in the corresponding next hop information stored in said routing table for the alternate route for said network node or cranking the call back to a preceding node which either forwards the setup message over the alternate route defined using the next hop information stored in its routing table for the alternate route or again cranks the call back to a further preceding node.