A comparative study on the coherent approaches to cooperation between TCP and ATM congestion control algorithms

Numerous studies have indicated that ATM available bit rate (ABR) service can provide low-delay, fairness, and high throughput, and can handle congestion effectively inside the ATM network. However, network congestion is not really eliminated but rather it is pushed out to the edge of the ATM network, packets from TCP sources competing for the available ATM bandwidth are buffered in the routers or switches at the network edges, causing severe congestion, degraded throughput, and unfairness. This poor performance is mainly due to the uncoordinated interaction between the congestion control mechanism of TCP and ATM. It is well accepted that some form of cooperation at edge device would help to control TCP traffic flow over ATM more effectively. We have previously proposed the fair intelligent explicit window adaptation (FIEWA) scheme and fair intelligent ACK bucket control (FIABC) scheme. The key idea is to combine the feedback information from the receiver, from the underlying ATM network, and from the local information at the edge device intelligently to explicitly/implicitly control the TCP rate. We present a comparative simulation study on our schemes with other established schemes; to identify the characteristics of each different scheme; and to indicate the requirement for a fairer, simpler and more robust coherent approach at the edge device.