Fair and reliable hop-by-hop flow control

Abstract

Asynchronous transfer mode networks can support different services with different quality of service requirements. Among all service types, available bit rate (ABR) is used primarily for transferring data files. Flow control is essential in ABR service. In this paper, we propose a new hop-by-hop credit-based flow control scheme with shared buffers. In this scheme, we introduce the concept of request cells to let upstream stations request credits from downstream stations such that downstream stations know the transmission requirements of upstream stations in the early stages of transmission. This allows the downstream stations to arrange their buffer spaces for different virtual connections (VCs) according to real needs, priorities, and fair access of different VCs. Simulation results show that the scheme improves the total throughput compared to the traditional credit-based flow control scheme, flow controlled virtual connections, without shared buffers under the same conditions. In one simulation, the total throughputs are increased by as many as 16.4%.