Testing Policing in ATM Networks

The Asynchronous Transfer Mode (ATM) is a network technology that can satisfy the quality-of-service requirements of many different types of traffic. The ability of ATM to handle many different types of traffic and its ability to operate at high bandwidths position it to be one of the core technologies behind future broadband wide area networks and the Internet. To provide quality-of-service guarantees, ATM relies crucially upon avoiding network congestion. Congestion can result in unacceptably large cell loss or delays. Cells that are lost may have to be retransmitted, which can result in increased congestion. Cells with excessive delays can cause higher-layer protocol timers (e.g., TCP/IP timers) to expire, which will result in even more cells being retransmitted. For video traffic, excessive delays or cell delay variation can result in underflow in the video decoder buffers. This can cause jagged movements or screen freezes when playing back the video.