A PERFORMANCE FLflEY OF ERICA AND ERICA+ SWITCH SCHEMES FOR ABR TRAFFIC IN ATM NETWORKS

Abstract

Congestion occurs in the computer network when the resource demands exceed the capacity. Packet may be lost due to large queue built up in the network. During congestion, the network throughput may drop and the path delay may become very high. A congestion control scheme helps network recover from the congestion state. A congestion avoidance scheme allows a network to operate in the region of low delay and high throughput. Such schemes prevent the network from entering the congested state. Congestion scheme is a prevention scheme. In this dissertation, the two congestion avoidance schemes, ERICA and ERICA+, for ABR service in ATM network are studied and their performances are evaluated. In ERICA, and ERICA+ (a variation to ERICA), the switches monitor their input load on each link and determine a load factor, the available capacity, and the number of currently active virtual channels. This information is used to give the feedback to sources about the rate at which they should transmit. Also, a simple addition to these schemes is proposed. This proposal is used to solve the problems: sudden queue built up at switches, large fluctuation in transmitted rate of sources, associated with the bursty sources as they form the bulk of traffic.