US 7,333,438 B1Granted

Priority and policy based recovery in connection-oriented communication networks

AssigneeNortel Networks Limited

InventorsSameh A. Rabie, Tong Shan

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Abstract

A recovery method for use in a connection-oriented network having nodes interconnected by links for establishing connections within the network, the method described enables the recovery of connections in the network in the event of a failure. The recovery method includes the following steps: (a) assigning connection re-routing priority to the connections in the network based on configured polices in response to the failure; and (b) creating release message bundles based on the assigned connection re-routing priority for use by the nodes in the network to recover connections. More specifically, a failure (e.g., link failure) could affect hundreds or thousands of connections passing through a node. To recover these connections, the node determines which connections should be recovered first and which connections can wait (or may never be recovered). The recovery method determines the priorities of re-routing connections after failure. After the re-routing priorities are determined for connections, the present invention provides mechanisms for bundling release messages and pacing the messages using hold-off timers to maximize the recovery of connections based on various network configurations and implementations.

Claims37

Dependent claims

A method for use in a connection-oriented network comprising a plurality of nodes interconnected by a plurality of links for establishing connections within the network, the method enabling the recovery of connections in the network in the event of a failure therein, the method comprising:

(a) assigning connection re-routing priority to the connections in the network based on configured polices in response to the failure;
(b) creating release message bundles based on the assigned connection re-routing priority for use by the nodes in the network to recover connections which includes:
(b1) creating a plurality of bundles of release messages of recovery requirements based on priority with reference to the re-routing in the network, the created bundles of release messages being in bundling order, the bundling ordered release messages being sent to nodes of the network;
and
(c) if step (b1) is performed in a node which is neither a call originated nor a call destined node, sending a prescribed bundle of release messages to the plurality of nodes in the network which includes:
(c1) sending a first bundle of the bundling ordered release messages;
and in a case of another bundle being required to be sent, sending another bundle of the bundles of release messages after a predetermined hold-off timer value, wherein an initial value of the predetermined hold-off timer is determined from:
max{(tprop,i)+(tproc,i)+(trout,i) for all connections 1<i<N in a group, where (tprop,i) represents propagation delay between a current node and a source node of a connection “i”, (tproc,i) represents processing time of the release message at the source node of the connection “i”:
(trout,i) represents re-routing time at the source node of connection “i”;
and N is the number of connections, the current node being a node in the network detecting the failure and sending release messages to nodes of affected connections and the source node being an originating edge node of the connection.

7 more elements

An apparatus for use in a connection-oriented network comprising a plurality of nodes interconnected by a plurality of links for establishing connections within the network, the method enabling recovery of connections in the network in the event of a failure therein, the apparatus comprising:

(a) a mechanism configured and adapted to assign connection re-routing priority to the connections in the network based on configured polices in response to the failure;
(b) a mechanism configured and adapted to create release message bundles based on the assigned connection re-routing priority for use by the nodes in the network for recovering connections which includes:
(b1) a mechanism configured and adapted to create a plurality of bundles of release messages of recovery requirements based on priority with reference to the re-routing in the network, the created bundles of release messages being in a bundling order, the bundling ordered release messages being sent to nodes of the network;
and
(c) if the (b1) mechanism is situated in a node which is neither a call originated nor a call destined node, the apparatus comprises a further mechanism for sending a prescribed bundle of release messages to the plurality of nodes in the network, the further mechanism including;
(c1) a mechanism configured and adapted to send a first bundle of the bundling ordered release messages and, in a case of another bundle being required to be sent, sending another bundle of the bundles of release messages after a predetermined hold-off timer value, wherein an initial value of the predetermined hold-off timer is determined from:
max{(tprop,i)+(tproc,i)+(trout,i) for all connections 1<i<N in a group, where (tprop,i) represents propagation delay between a current node and a source node of a connection “i”, (tproc,i) represents processing time of the release message at the source node of the connection “i”;
(trout,i) represents re-routing time at the source node of connection “i”;
and N is the number of connections the current node being a node in the network detecting the failure and sending release messages to nodes of affected connections and the source node being an originating edge node of the connection.

6 more elements

A computer program product for use in a connection-oriented network comprising a plurality of nodes interconnected by a plurality of links for establishing connections within the network to enable recovery of connections in the network in the event of a failure therein, the computer program product comprising computer readable medium encoded with computer program code for:

(a) assigning connection re-routing priority to the connections in the network based on configured polices in response to the failure;
(b) creating release message bundles based on the assigned connection re-routing priority for use by the nodes in the network to recover connections which includes:
(b1) creating a plurality of bundles of release messages of recovery requirements based on priority with reference to the re-routing in the network, the created bundles of release messages being in a bundling order, the bundling ordered release messages being sent to nodes of the network;
and
(c) if step (b1) is performed in a node which is neither a call originated nor a call destined node, sending a prescribed bundle of release messages to the plurality of nodes in the network which includes:
(c1) sending a first bundle of the bundling ordered release messages;
and in a case of another bundle being required to be sent, sending another bundle of the bundles of release messages after a predetermined hold-off timer value, wherein an initial value of the predetermined hold-off timer is determined from:
max{(tprop,i)+(tproc,i)+(trout,i) for all connections 1<i<N in a group, where (tprop,i) represents propagation delay between a current node and a source node of a connection “i”, (trout,i) represents processing time of the release message at the source node of the connection “i”:
(trout,i) represents re-routing time at the source node of connection “i”;
and N is the number of connections, the current node being a node in the network detecting the failure and sending release messages to nodes of affected connections and the source node being an originating edge node of the connection.

7 more elements

Dependencies are inferred from the claim text.