Selective BECN schemes for congestion control of ABR traffic in ATM LAN

Abstract

There is a growing interest in high speed data transfer by adopting the asynchronous transfer mode (ATM) technique on a local basis. To this end ATM based LANs must provide available bit rate (ABR) services in which a source does not specifies its traffic characteristics, but only its peak rate, and transmits without any bandwidth reservation. Congestion control is a critical issue for such a service. It can be achieved by regulating the actual source transmission rate using backward explicit congestion notification (BECN) information, i.e. control cells transmitted back to the source. Although this feedback mechanism can be used due to the low distance its effectiveness must be carefully studied in order to avoiding wasted bandwidth. Two selective BECN schemes are proposed and extensive simulation results are presented. It is shown that a selective scheme assures a remarkable reduction in the number of BECN cells necessary to obtain the same performance when compared to trivial schemes.