Available Bit Rate (ABR) service is becoming more and more important in Asynchronous Transfer Mode (ATM) networks because it can be used to fill in the band-width slack left by the scheduled traffic. Recently, two flow control schemes for ABR traffic were under active discussion, They are credit-based flow control scheme and rate-based flow control scheme. Credit-based flow control scheme can completely avoid cell loss. However, its main drawback is the per-VC large buffer requirement. Therefore, the approach is not scalable to a large number of VCs. On the other hand, rate-based flow control, such as FECN and BECN, requires less buffer. Unfortunately, the rate-based schemes are generally slow in response to congestion. Worst still, these schemes are usually unfair....[ Read more ]

Available Bit Rate (ABR) service is becoming more and more important in Asynchronous Transfer Mode (ATM) networks because it can be used to fill in the band-width slack left by the scheduled traffic. Recently, two flow control schemes for ABR traffic were under active discussion, They are credit-based flow control scheme and rate-based flow control scheme. Credit-based flow control scheme can completely avoid cell loss. However, its main drawback is the per-VC large buffer requirement. Therefore, the approach is not scalable to a large number of VCs. On the other hand, rate-based flow control, such as FECN and BECN, requires less buffer. Unfortunately, the rate-based schemes are generally slow in response to congestion. Worst still, these schemes are usually unfair.

In this thesis, three flow control schemes are introduced. The first one is a modification of the credit-based flow control, called the two-level flow control scheme, which can reduce the buffer requirement of the original credit-based scheme and can enhance the efficiency. Another scheme, called the Max-Min scheme, is a rate-based flow control scheme. The scheme can rapidly achieve the max-min fairness allocation and reduce the peak queue lengths of the bottleneck switches. To solve the problem of different source-to-switch separations for different connections, another rate-based scheme, called the Max-Min Scheme with Delayed Adjustment, is proposed. With this, the peak queue lengths at the switches are further reduced.