The OSU scheme for congestion avoidance in ATM networks: Lessons learnt and extensions

The OSU scheme is a rate-based congestion avoidance scheme for asynchronous transfer mode (ATM) networks using explicit rate indication. This work was one of the first attempts to define explicit rate switch mechanisms and the resource management (RM) cell format in ATM networks. The key features of the scheme include explicit rate feedback, congestion avoidance, fair operation while maintaining high utilization, use of input rate as a congestion metric, O(1) complexity. This paper presents an overview of the scheme, presents those features of the scheme that have now become common features of other switch algorithms and discusses three extensions of the scheme.