Method of path restoration in an ATM network utilizing point to point switched virtual circuits

In an Asynchronous Transfer Mode (ATM) network including a source and destination user, end nodes including source and destination nodes, a first plurality of transit nodes and a second plurality of transit nodes, a method of establishing a redundant path, said method comprising the steps of:

• establishing a first active switch table and a first redundant switch table on said source node;
• establishing a second active switch table and a second redundant switch table on said destination node;
• establishing a first Switched Virtual Circuit (SVC) call from said source user to said destination user;
• indicating to said destination node and any intermediary transmit nodes, via a first indication, that said first SVC is to function as an active path;
• configuring said second active switch table in said destination node and said first plurality of transit nodes, both in response to said first indication, and said first active switch table in said source node to utilize said first SVC as the active path in a redundant call;
• establishing a second SVC call from said source node to said destination node;
• indicating to said destination node and any intermediary transmit nodes, via a second indication, that said second SVC is to function as a redundant path;
• and
• configuring said second redundant switch table in said destination node and said second plurality of transit nodes, both in response to said second indication, and said first redundant switch table in said source node to utilize said second SVC as the redundant path in a redundant call utilizing a global call ID to identity said second SVC call as the redundant path.

In an Asynchronous Transfer Mode (ATM) network including a source and destination user, end nodes including source and destination nodes, a first plurality of transit nodes and a second plurality of transit nodes, a method of switching to a redundant path previously established, said method comprising the steps of:

• detecting the occurrence of a link failure by detecting nodes on either side of the link failure thus creating a broken active path;
• sending a loopback cell back from each detecting node to its respective end node;
• looping back cells arriving at said detecting nodes to their respective end nodes;
• detecting the arrival of said loopback cell at said end nodes;
• sending a flush cell out onto the broken active path by each said end node;
• buffering cells received from said source user and said destination user in a buffer within each end node;
• transmitting cells received from said broken active path over the redundant path;
• transmitting the contents of said buffer on each said end node onto the redundant path;
• and
• transmitting cells received from said source user and said destination user directly onto the redundant path.