Methods and apparatus for restoring connections in an ATM network

A method of operating a switch in a network including a plurality of switches, a source device, and a destination device, the method comprising the steps of:

• monitoring to detect a node or link failure affecting a connection in an established communication path between the source and destination devices thereby affecting a call using the established communication path;
• operating the switch in response to the detection of a node or link failure, to determine if the switch is on the source or destination device side of the node or link failure;
• if it is determined that the switch is on the destination side of a detected node or link failure, operating the switch to initiate a limited capacity release operation;
• if it is determined that the switch is on the source side of a detected node or link failure, operating the switch to initiate a re-routing operation, the re-routing operation involving the steps of:
• assigning a new virtual connection identifier to the affected call;
• accessing alternate route information stored in a routing table included within the switch to identify an alternate route to be used to re-establish the connection with the destination device;
• and
• transmitting a re-route set-up message used to re-establish the connection with the destination device.

A method of operating a switch in a network including a plurality of switches, a source device, and a destination device, the method comprising the steps of:

• monitoring to detect a node or link failure affecting a connection in an established communication path between the source and destination devices thereby affecting a call using the established communication path;
• operating the switch in response to the detection of a node or link failure, to determine if the switch is on the source or destination device side of the node or link failure;
• if it is determined that the switch is on the source side of a detected node or link failure, operating the switch to initiate a re-routing operation, the re-routing operation involving the steps of:
• assigning a new virtual connection identifier to the affected call;
• accessing alternate route information stored in a routing table included within the switch to identify an alternate route to be used to re-establish the connection with the destination device;
• and
• transmitting a re-route set-up message used to re-establish the connection with the destination device;
• and
• further, in response to receiving a re-route setup message including a call identifier, operating the switch to perform a resource availability check to determine if sufficient resources are available to service the call identified in the re-route setup message request.

A method of operating a switch in a network including a plurality of switches, a source device, and a destination device, the method comprising the steps:

• monitoring to detect a node or link failure affecting a connection in an established communication path between the source and destination devices thereby affecting a call using the established communication path;
• operating the switch in response to the detection of a node or link failure, to determine if the switch is on the source or destination device side of the node or link failure;
• if it is determined that the switch is on the source side of a detected node or link failure, operating the switch to initiate a re-routing operation, the re-routing operation involving the steps of:
• assigning a new virtual connection identifier to the affected call;
• accessing alternate route information stored in a routing table included within the switch to identify an alternate route to be used to re-establish the connection with the destination device;
• and
• transmitting a re-route set-up message used to re-establish the connection with the destination device;
• and
• further, upon receiving a re-route setup message including a call identifier, performing the following steps:
• determining if a call record in the switch corresponding to the call identifier, included in the re-route setup message, was created or updated in response to a previous re-route setup message corresponding to the same failure event;
• and
• upon determining that a call record in the switch corresponding to the call identifier, included in the re-route setup message, was created or updated in response to a previous re-route setup message corresponding to the same failure event performing the step of:
• transmitting a re-route loop clear message.

A method of operating a switch in a network including a plurality of switches, a source device, and a destination device, the method comprising the steps:

• monitoring to detect a node or link failure affecting a connection in an established communication path between the source and destination devices thereby affecting a call using the established communication path;
• operating the switch in response to the detection of a node or link failure, to determine if the switch is on the source or destination device side of the node or link failure;
• if it is determined that the switch is on the source side of a detected node or link failure, operating the switch to initiate a re-routing operation, the re-routing operation involving the steps of:
• assigning a new virtual connection identifier to the affected call;
• and
• wherein a single communication path is used to service a plurality of different calls corresponding to different applications, and wherein the switch provides calls using the same path different degrees of protection from premature connection release upon detecting a node or link failure affecting the single communication path.

A method of operating a switch in a network including a plurality of switches, a source device, and a destination device, the method comprising the steps:

• monitoring to detect a node or link failure affecting a connection in an established communication path between the source and destination devices thereby affecting a call using the established communication path;
• operating the switch in response to the detection of a node or link failure, to determine if the switch is on the source or destination device side of the node or link failure;
• if it is determined that the switch is on the source side of a detected node or link failure, operating the switch to initiate a re-routing operation, the re-routing operation involving the step of:
• assigning a new virtual connection identifier to the affected call;
• and
• wherein the step of initiating a re-routing operation further includes the steps of:
• determining if the switch detecting the failure is a source switch for the affected call;
• if it is determined that the switch detecting the failure is the source switch for the affected call, transmitting a re-route setup message;
• and
• if it is determined that the switch detecting the failure is not a source switch for the affected call transmitting a crank back message to the source switch for the affected call to cause the source switch to perform a re-route operation.

A method of operating a switch in a network including a plurality of switches, a source device, and a destination device, the method comprising the steps:

• monitoring to detect a node or link failure affecting a communication path between the source and destination devices;
• operating the switch in response to the detection of a node or link failure, to determine if the switch is on the source or destination device side of the node or link failure;
• and
• if it is determined that the switch is on the destination side of a detected node or link failure, operating the switch to initiate a limited capacity release operation to release reserved switch capacity no longer used by the affected communication path.

A switch for use in a network including a plurality of other switches, a source device, and a destination device, the switch comprising:

• means for monitoring to detect node or link failures affecting a connection in an established communication path;
• means for determining, in response to the detection of a node or link failure, if the switch is on the source or destination device side of the node or link failure;
• means for initiating a re-routing operation when it is determined that the switch is on the source side of a node or link failure, wherein said means for initiating includes:
• means for assigning a new virtual connection identifier to the affected call;
• means for accessing alternate route information stored in a routing table included within the switch to identify an alternate route to be used to re-establish the connection with the destination device;
• and
• means for transmitting a re-route set-up message used to re-establish the connection with the destination device.

A switch for use in a network including a plurality of other switches, a source device, and a destination device, the switch comprising:

• means for detecting a node or link failure affecting a communication path between the source and destination devices;
• means for determining, if the switch is on the source or destination device side of a detected node or link failure;
• and
• means for initiating a limited capacity release operation to release reserved switch capacity no longer used by the affected communication path.