Nortel Networks Corporation

Northern Telecom Limited

Ra'ed Yousif Awdeh

John Frank Pillar

Norman Allan Lyon

Osama S Aboul-Magd

Gregory Lloyd King

An apparatus and a computer readable storage medium having computer readable instructions for directing a processor to execute a method executable by the apparatus for adjusting policing cell rates at a switch interface, for cells received from a source in an allowed cell rate system. The method includes the steps of storing a current policing rate (PACR) in a current policing rate buffer, storing a plurality of policing rates and policing rate application times in respective policing rate and policing rate application time buffers and in response to the departure of a backward resource management cell to the source at time tb(j), setting the contents of the policing rate buffers and the policing rate application time buffers according to the relative magnitudes of the current policing rate and the contents of the policing rate buffers.

ABR policing method and apparatus

In an enhanced partial packet discard (PPD) methodology, if an end-of-packet cell is discarded for non-PPD reasons, all non-end-of-packet cells of the immediately following packet are discarded. When an end-of-packet cell may validly be discarded, a switch faced with an end-of-packet cell may discard that cell if the last cell admitted to the buffer was an end-of-packet cell. To reduce the likelihood of having to drop end-of-packet cells, a buffer is configured to include a partial packet discard threshold such that the buffer space between that threshold and the end of the buffer is reserved for use by end-of-packet cells.

Method and apparatus for enhanced partial packet discard

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 which can grow to a fair level even under special conditions.

Flow control mechanism of ABR traffic in ATM networks

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.

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Ottawa, Canada

Ra'ed Yousif Awdeh