Patent ID: 6215765
Filing Date: 2001-04-10
Classification: H04L,H04Q

Abstract:
A method of establishing a switched virtual circuit call in a digital communications network comprising a plurality of network nodes, each network node having a local static routing table providing next hop routing information to adjacent nodes, comprising the steps of:defining in said routing table a primary route and an alternate route to adjacent nodes;sending a setup message 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 for corresponding routing information; andsaid network node, based on the corresponding routing information, attempting to forward the setup message on the primary route; andif the primary route is not usable due to congestion or physical failure, said network node then attempting to forward the setup message on the alternate route; andif the alternate route is the same route on which the setup message is received, the network node then cranking the call back to a preceding node which either forwards the setup message over the alternate route defined in said preceding node's routing table or again cranks the call back to a further preceding node, and such process being repeated until the call setup message has been returned to a source thereof.