Comparing ATM credit-based and rate-based controls for TCP sources

TCP/IP traffic is likely to be one of the most heavily carried over ATM networks. However this kind of traffic is of connectionless nature and for this reason will be carried on an available bit rate (ABR) basis. In order to prevent the ABR traffic from congesting the network, special congestion control techniques have been devised. These schemes can be categorized in two major groups: rate-based and credit-based schemes. The most important representatives of these categories are respectively the proportional rate control algorithm (PRCA) and the flow controlled virtual circuit (FCVC). Since TCP/IP traffic is also controlled by the TCP window flow control, we present a comparison between PRCA and FCVC (via simulation of an ATM LAN) under TCP traffic. In this sense the performance measure we are mostly concerned with is the goodput. We investigate the impact of the burstiness of the guaranteed sources used as background traffic and the maximum size of TCP segments, which seems to be critical for the PRCA approach