Source routing method for fast connection re-establishment in response to early-arriving trouble report messages

A source routing method for routing a call from a source node through a communication network in which a plurality of nodes are interconnected by communication links, wherein the source node is provided with a route table, a network resource table and a timed resource table, said route table storing data of a plurality of routes from each of said nodes to other nodes of the network, the network resource table storing data of available network resources of said links, wherein contents of the timed resource table are valid for a predefined duration, the method of said source node comprising the steps of:

• a) updating the network resource table in response to a first message received from the network whenever there is a change in the available network resources, said first message being flooded through the network to exchange most recent resource data among said nodes;
• b) updating the timed resource table in response to a second message from the network if said change in the available network resources occurs when a connection is being progressively established or already established from said source node so that data of most recent resource of a route of the connection is installed in the timed resource table, said second message arriving at said source node earlier than said first message;
• c) fetching a route from said route table in response to a connection setup message from a user terminal;
• d) comparing a requirement requested by the user terminal with the resource data of the fetched route in the timed resource table if the valid contents of the timed resource table are relevant to the fetched route;
• e) comparing said requirement with the resource data of the fetched route in the network resource table if the contents of the timed resource table are invalid or the valid contents of the timed resource table are irrelevant to the fetched route;
• and
• f) establishing a connection via the fetched route if the resource data of the fetched route in either the timed resource table or the network resource table indicates that the fetched route can support said requirement.

A source routing method for routing a call from a source node through a communication network in which a plurality of nodes are interconnected by communication links, wherein the source node is provided with a working route table, a spare route table, a network resource table and a timed resource table, said working route table storing data of a plurality of working routes from each of said nodes to other nodes of the network, said spare route table storing a plurality of spare routes from each of said nodes to said other networks, the network resource table storing data of available network resources of said links, wherein contents of the timed resource table are valid for a predefined duration, the method of said source node comprising the steps of:

• a) updating the network resource table in response to a first message received from the network whenever there is a change in the available network resources, said first message being flooded through the network to exchange most recent resource data among said nodes;
• b) updating the timed resource table in response to a second message from the network if said change in the available network resources occurs when a connection is being progressively established or already established from said source node so that data of most recent resource of a route of the connection is installed in the timed resource table, said second message arriving at said source node earlier than said first message;
• c) fetching a working route from said working route table in response to a connection setup message from a user terminal;
• d) comparing a requirement requested by the user terminal with the resource data of the fetched working route in the timed resource table if the valid contents of the timed resource table are relevant to the fetched working route;
• e) comparing said requirement with the resource data of the fetched working route stored in the network resource table if the contents of the timed resource table are invalid or the valid contents of the timed resource table are irrelevant to the fetched working route;
• and
• f) fetching a spare route from the spare route table if the resource data of both of said timed resource table and said network resource table indicates that the fetched working route does not support said requirement;
• g) comparing said requirement with the resource data of the fetched spare route of the network resource table;
• and
• h) establishing a connection via the fetched working route if the resource data of the fetched working route in either the timed resource table or the network resource table indicates that the fetched working route cannot support said requirement, or via the fetched spare route if the resource data of the fetched spare route in the network resource table indicates that the fetched spare route can support said requirement.