Patent ID: 6115359
Filing Date: 2000-09-05
Classification: H04L,H04Q

Abstract:
A method of controlling the flow of ABR ATM (available bit rate asynchronous transfer mode) cells in an ATM network wherein a plurality of connections through the ATM network are each guaranteed a MCR (minimum cell rate) including an ABR connection, cells above the ABR connection's MCR being referred to as ABR elastic cells; comprising signalling an ER (explicit rate) to a source of cells on the ABR connection, the signalling being carried out by way of passing along the ABR connection an RM (resource management) cell containing the ER, each switch along the ABR connection in sequence receiving the RM cell containing the ER, having an opportunity to insert a new decreased value of ER into the RM cell before transmitting on an output port in the switch to the next switch in the ABR connection; wherein the new decreased value of ER is obtained by executing the steps of:determining an estimate of an input ABR elastic cell rate Port.sub.-- EIR of cells destined for transmission on the particular output port;determining an estimate of an output reservation at the output port for cells having a higher priority than ABR elastic, HPE.sub.-- reserve;determining a port elastic allocatable rate Port.sub.-- EAR as a function of the output port's capacity, and HPE.sub.-- reserve;determining a steering factor SF for the port as a function of Port.sub.-- EAR and Port.sub.-- EIR;determining an elastic offered rate EOR for the particular connection according to Port.sub.-- EAR*SF*RF, where RF is a rationing factor for the particular connection;determining a local ER for the connection according to local.sub.-- ER=EOR+MCR;determining ER to be the minimum of the ER in the RM cell and local.sub.-- ER.