Northern Telecom Limited

Osama S Aboul-Magd

Ra'ed Yousif Awdeh

Rungroj Kositpaiboon

Marianne J Morin

Nathalie Giroux

Marcel Lemay

An ATM network carries several categories of services, each having its own traffic characteristics and performance requirements. The ABR (available bit rate) service category is the only existing one suited for high-reliability data communications, such as file transfer, LAN emulation, etc. The invention relates to the control of ABR traffic flow in an ATM network, to quickly utilize the bandwidth left unused by higher priority service categories while minimizing ABR cell loss, and maintaining fairness among ABR connections. On each ABR connection, the source end system periodically sends RM (resource management) cells to the corresponding destination end system which loops them back to the source. The ATM network may instruct the ABR sources of the exact rates it can support by modifying a certain field in the RM cells. The invention relates to techniques of deriving the proper explicit cell rate for each ABR connection.

Flow control of ABR traffic in ATM networks

A Frame Relay network must implement a rate (bandwidth) enforcement function at the access in the network so that service subscription violation by some users will not cause performance or throughput degradation of other users' service. A novel rate enforcement technique is disclosed. The new technique makes use of a 'leaky bucket' algorithm in which a portion of one 'leaky bucket' is set aside for high priority frames only.

Growing community of inventors

Nepean, Canada

Osama S Aboul-Magd