The Generic Cell Rate Algorithm ( GCRA ) 7 3 Leaky Bucket Admission Schemes

The ATM Forum has recently defined a new data service called Guaranteed Frame Rate (GFR) Service. This new service aims to support minimum bandwidth guarantee for a VC and allows any excess bandwidth in the network to be shared among the contending VCs in a fair manner. It was proposed that the service requirement of GFR may be supported using the Generic Cell Rate Algorithm (GCRA), or equivalently, a leaky-bucket algorithm. Such an approach has significant implementation and cost advantage because most commercial ATM switches already have hardware for GCRA, which is used for example in VBR service. However, previous ATM Forum contributions showed that a straightforward application of GCRA may not always guarantee both minimum bandwidth and fairness of excess bandwidth, particularly when bursty TCP traffic is considered. In this paper, we present an enhanced leaky-bucket buffer admission scheme in switches with FIFO queuing for supporting the GFR service requirements. Simulation results are presented to show that our scheme performs well under various TCP and UDP traffic environment. Thesis Supervisor: Kai-Yeung Siu Title: Assistant Professor