International Business Machines Corporation

Philip F Chimento, Jr

Diane Phylis Pozefsky

James P Gray

Andrew Hilliard Arrowood

John E Drake, Jr

Levent Gun

Alan E Baratz

John L Eisenbies

Karla J Norsworthy

Vidyadhar G Kulkarni

A packet communications network is adapted for efficiently handling of multi-priority traffic (such as multi-media traffic) by defining an access algorithm that not only ensures the requested loss probabilities for both priorities of traffic, but also optimizes the bandwidth required to carry both priority classes. A buffer having a properly sized occupancy threshold admits high priority traffic if there is room in the buffer, but admits lower priority traffic only if the buffer occupancy is below the occupancy threshold. The resulting consolidated multi-priority traffic can then be characterized by an effective bandwidth which increases the packet network capacity substantially. The multi-priority access mechanisms require little or no changes in the prior art access mechanisms and utilize pre-existing leaky bucket, route selection and link metric mechanisms of the prior art.

Traffic management in packet communications networks

Each network node in a communications network maintains its own copy of the network topology database defining network resources. Each resource record contains a 'timer' field which is initially set to a maximum value but which may be decremented on a daily basis. If the timer field is decremented to zero without being reset, the node unilaterally removes the resource record from its copy of the database. The timer field will normally reach zero only for obsolete resource records since each network node responsible for a resource broadcasts a timer-resetting message for the resource (1) each time the resource status changes, (2) when the node first joins or rejoins the network, and (3) on a periodic (weekly) basis regardless of whether conditions (1) or (2) have occurred.

Method of maintaining a topology database

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Durham, NC, United States of America

Philip F Chimento, Jr