Telecommunication network trouble recovery system

A method of recovering a failed communication link between first and second terminus nodes in a telecommunication network which comprises:

• a) broadcasting from the first of said terminus nodes to each recipient node connected thereto by a link affording spare bandwidth a message comprising the identity of the first broadcasting node and the specification of a bandwidth which is the lesser of the bandwidth required to recover said failure and the maximum spare bandwidth afforded on said link;
• b) recording at each recipient node the bandwidth specified in each respective message received at said recipient node and the identity of the node from which said message was received;
• c) broadcasting from each recipient node to each subsequent node connected thereto by a link affording spare bandwidth a revision of the received message comprising the identity of the then broadcasting node and the specification of a bandwidth which is the lesser of the maximum bandwidth then on record at the respective recipient node and the maximum spare bandwidth afforded on said link;
• d) repeating up to a predetermined maximum number of times step b) and, except at the second of said terminus nodes, step c);
• e) after a predetermined period of time following said failure, identifying from the data recorded at the second of said terminus nodes the adjacent node from which was received the message specifying the maximum bandwidth;
• f) transmitting from said second terminus node to the identified adjacent node a message acknowledging said maximum bandwidth;
• g) identifying from the data recorded at the adjacent node the next adjacent node from which was received the message specifying the maximum bandwidth;
• h) transmitting from the adjacent node to the identified next adjacent node a message comprising the initial bandwidth acknowledgement;
• i) repeating steps g) and h), except at the first of said terminus nodes;
• and
• j) cross-connecting the respective acknowledged bandwidth links at the identified nodes therebetween.

A method of recovering a failed communication link between first and second terminus nodes in a telecommunication network wherein the first of said terminus nodes broadcasts on links to neighboring nodes a path restoration request message which is further broadcast by subsequent neighboring nodes, the second of said terminus nodes receives various of said broadcast messages from neighboring nodes and returns messages to said first terminus node on path links utilized for said broadcast messages, and network recovery paths are established on said return message paths characterized in that

• a) the initial broadcast messages identify the then broadcasting node and specify a bandwidth which is the lesser of the bandwidth required to recover said failure and the maximum spare bandwidth afforded on the broadcast link;
• b) each further broadcast message identifies the then broadcasting node and specifies a bandwidth which is the lesser of the bandwidth specified in the message received by said broadcasting node and the maximum spare bandwidth afforded on the broadcast link;
• c) said second terminus node returns a message to said first terminus node only on the path whose initial link is to the second terminus neighboring node whose request message specified the maximum bandwidth;
• and
• d) a network recovery path is thereby established which affords the largest minimum bandwidth link.