US 6,215,765 B1Granted

SVC routing in network with static routing tables

AssigneeAlcatel Networks Corporation

InventorsShawn McAllister, Nutan Behki, Richard Chan

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Abstract

A method is disclosed for establishing a switched virtual circuit in a digital network having network nodes with static routing tables. The static routing tables contain at least primary and alternate routing data. When a node is unable to forward a call over its outgoing primary route due to congestion or physical failure and its alternate route is the same as the route on which a call setup request arrived, it clears the call at that node and sends a crankback message to the preceding node, which responds to the crankback message to attempt to dynamically re-route the call over the alternate route stored in the routing table of the preceding node. If the attempt is unsuccessful, it sends the message back to the next preceding node and so on.

Claims7

Dependent claims

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;
and
said network node, based on the corresponding routing information, attempting to forward the setup message on the primary route;
and
if 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;
and
if 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.

6 more elements

Dependencies are inferred from the claim text.