PRIORITIZED STATE-DEPENDENT BUFFER-MANAGEMENT SCHEMES IN ATM NETWORKS

Abstract

Synchronous Transfer Mode (STM), the transport mechanism for Integrated Services Digital Network (ISDN), has been found to face- fundamental problems like complex switching and -rigid channel structure when considered for- broadband access to -ISDN. So Asynchronous Trans-fer--Mode -(ATM)- was _chosen - as-switching and multiplexing technique by CCITT for the broadband access. to fSD-N. The User Network Interface (UN!) offers one physical channel over wh-ich connections are multiplexed- using short, fixed length packets called cells. ATM is connection oriented. Cells are self routed based on -their header •i-nformation. In this way, ATM networks can transmit various -types of information in a flexible way. A study of buffer management scheme using two different prioritized state-dependent service disciplines is presented. It improves the cell delay for each traffic class i.e., delay sensitive and loss sensitive, and reduces the cell' loss rate of loss-sensitive traffic class. Two state dependent pr--iority schemes-namely Arrival Rate Based State Dependent (ARBSD) priority scheme and Relative State-Dependent (RSD) priority scheme are simulated and compared thr-ougit_ performance analysis. Simulation of the same was done for two types of traffic models i.e., random traffic model and bursty traffic model. The Static priority scheme,the Longest Line. First (LLF), the Shortest Line First (S.LF) and the Oldest Customer First (OCF) schemes are simulated and their performances compared with the ARBSD and the RSD priority schemes.