Block Loss Reduction in ATM Networks

摘要

Traditional approaches to guaranteeing Quality-of-Service (QoS) in ATM networks have focused on performance metrics such as cell loss probability, end-to-end cell delay and delay jitter. However, the block loss rate is a more meaningful metric for applications such as medical imaging and real-time video, and to high-level protocols such as IP which will use ATM as the transport mechanism. A block is defined as a group of consecutive ATM cells. For instance, a block may correspond to an IP datagram or to a macroblock within a medical image. A block loss occurs when a single cell from a block is lost. Consequently, we propose a technique for reducing block loss in ATM networks. Our method combines two well-studied approaches for minimizing the impact of information loss during transport over ATM networks which have been considered independently of each other in the past: priority-based cell discarding and forward error correction (FEC). We present analysis which shows that our scheme reduces the block loss rate by several orders of magnitude for many cases of interest.