International Business Machines Corporation

Kathryn E Clarke

Diane Phylis Pozefsky

James P Gray

John E Drake, Jr

William E Siddall

Andrew Hilliard Arrowood

Lee M Rafalow

Alan E Baratz

Melinda R Pollard

John L Eisenbies

Terence Dale Smetanka

Karla J Norsworthy

In a communications network, each network node can maintain its own list of network resources in a topology database. When the state of a resource 'owned' by a particular node changes, that node broadcasts a topology database update (TDU) message to adjacent nodes. Each adjacent node updates its own topology database and rebroadcasts the message. To minimize the amount of information that must be included in TDU messages when two nodes are reconnected after an outage, each node assigns flow reduction sequence numbers (FRSNs) to TDU meassages and keeps a record of the FRSN for the last TDU message sent to an adjacent node. The node also records, for each resource in its database, the FRSN of the last TDU message including that resource. When two nodes are reconnected, the sending node includes in the TDU message only those resources having a FRSN greater than the FRSN assigned to the last TDU sent to the adjacent node to which the TDU message is directed.

Method of reducing the amount of information included in topology

A least weight route computation algorithm for use in computing routes through a data communications network is improved by recording the number of equally weighted paths to a particular node through different predecessor nodes. If a route must be selected to the particular node, the relative numbers of equally weighted routes through different predecessor nodes determines the probability with which a route will be selected through the particular predecessor node.

Method of selecting least weight routes in a communications network

When computing a least weight path from an origin node to a destination node in a data communication network, a route-computing network node uses information provided by the origin and destination nodes to compute least weight routes from those nodes to adjacent network nodes. The route-computing network node uses information in the topology database to compute least weight routes from network nodes adjacent the origin node to network nodes adjacent the destination node. The results of the computations are concatenated to determine an optimum route from the origin node to the destination node. The topology database need not include information about the transmission groups connecting the origin/destination nodes to network nodes.

Method for selecting least weight end node to end node route in a data

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Little Silver, NJ, United States of America

Kathryn E Clarke