Patent ID: 6373844
Filing Date: 2002-04-16
Classification: H04L

Abstract:
An ATM (Asynchronous Transfer Mode) system with ABR (Available Bit Rate) function for optimally using a network resource, comprising:a VS/VD (Virtual Source/Virtual Destination) for switching cells from one of two types of feedback loops to the other, congestion information being transmitted to the feedback loops, said VS/VD having an upstream segment circuit portion and a downstream segment circuit portion, wherein the upstream-segment circuit portion comprises: a cell identifying portion for detecting an FRM (Forward Resource Management) cell received corresponding to destination behavior so as to process the FRM cell; an RM (Resource Management) cell folding portion for terminating the FRM cell detected by said cell identifying portion and transmitting a BRM (Backward Resource Management) cell; and a CCR extracting portion for extracting CCR (Current Cell Rate) information from the BRM cell transmitted by said RM cell folding portion, and wherein the downstream segment circuit portion comprises: an ER comparing/updating portion for comparing an ER (Explicit Rate) area of a BRM cell received from a downstream cell with the CCR information extracted by said CCR extracting portion, updating the ER area of the received BRM cell with a smaller value of the ER area and the CCR information, and outputting the updated ER area as a new BRM cell so as to process the received BRM cell corresponding to source behavior; a BRM cell terminating portion for terminating the new BRM cell that has been updated by said ER comparing/updating portion; a rate controlling portion for receiving congestion information from said BRM cell terminating portion and deciding a cell transmission rate corresponding to the received congestion information; an FRM cell generating portion for generating a new FRM cell with the CCR information decided by said rate controlling portion; and a VS buffer for temporarily storing a cell that has been identified as a data cell by said cell identifying portion until said rate controlling portion decides a transmission timing.