Packet-switched network having alternate virtual paths

Claim 1

A packet switched communications system comprising a plurality of switching nodes, each switching node being connected by a transmission line to each one of a plurality of adjacent switching nodes, the transmission line including communication links for transporting packets and a service link for transporting a fault message, each of said switching nodes comprising: a switching network for routing packets from inputs to outputs of the network according to a virtual path identifier contained in the packets; cross-connect means for establishing connections between the communication links and the inputs of said switching network; a memory for storing data indicating link-to-link connections associated with normal virtual paths and data indicating link-to-link connections associated with alternate virtual paths; fault detector means for detecting a failure in said communication links; fault message transceiver means coupled to said fault detector means and to the service links terminated in adjacent switching nodes for transmitting a fault message identifying a faulty communication link to an adjacent switching node, and relaying a like fault message received from an upstream switching node to a downstream switching node; and means for retrieving data from said memory corresponding to the faulty communication link identified by the fault message either from said fault detector means or said fault message transceiver means and causing said cross-connect means to reconfigure connections according to the retrieved data so that the route of the packets is switched from a normal virtual path to an alternative virtual path.