International Business Machines Corporation

Robert D Clouston

John E McGinn

John H Zeiger

William E Siddall

Leo J Bartolanzo, Jr

John S Graham, Jr

A topology manager external to a communications network manages the network and in particular resolves conflicting topology information about the network by dividing the management of the topology data base into two operations--a collection instance and a resolution layer. A collection instance collects all information that its agent node has about the topology of the network. This topology information is processed by the collection instance to determine for each resource in the network whether the resource is new, reachable or has experienced a reachability change. The resolution layer receives the topology resource information from each collection instance. When a resource is indicated as reachable by a collection instance, that resource is placed on a Reach list as an entry from that collection instance. If the collection instance indicates the resource from that collection instance is no longer reachable, the resolution layer will remove that resource entry from the Reach list, and look for another Best Reach entry for the resource. If the network fragments and nodes go down and come back up, the resolution layer can resolve conflicts in resource information from separate collection instances to select the most current information for a resource.

Resolving conflicting topology information

A process for selecting a least weight path between two nodes in a data communication network uses partial trees created and cached in prior route selection operations. All root nodes on possible paths between the two nodes are identified. Any cached tree having a root matching one of the identified root nodes is retrieved from storage. If necessary, each retrieved tree is extended until it includes all possible destination nodes. The extended and/or retrieved trees are used to select the least weight path between the two nodes. The extended tree is then cached for possible use in future route selection operations.

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Cary, NC, United States of America

Robert D Clouston