Evaluation of congestion control protocols for ABR traffic over ATM networks

✍ Scribed by W. Melody Moh; Madhavi Hegde; Niki Pissinou

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 313 KB
• Volume: 13
• Category: Article
• ISSN: 1074-5351
• DOI: 10.1002/(sici)1099-1131(200002)13:1<1::aid-dac399>3.0.co;2-0

✦ Synopsis

Congestion control is very important for e!ective and stable operation of ATM (Asynchronous Transfer Mode) networks. Owing to the bursty and unpredictable characteristic of data network tra$c, its congestion control is particularly a challenge for network researchers and designers. The ATM Forum has recently adopted rate-based congestion control for ABR (Available Bit-Rate) tra$c which is the service class de"ned for data network applications. However, there is a number of congestion control schemes prevalent. ATM Forum has decided not to specify switch behaviour for ABR tra$c; this has further introduced additional ambiguity. Consequently, an evaluation and comparison of the existing protocols would provide valuable guidance for network designers and engineers; it would also give insight for researchers to explore the essence of di!erent congestion control schemes. In the "rst part of this paper, we investigate the e!ectiveness of ABR congestion control in the presence of bursty source tra$c and the relationship between the burst time scale and the ABR control time scale. Two ABR congestion control schemes, the ABR Explicit Forward Congestion Indication (EFCI) and ABR Congestion Indication (CI) schemes, are compared with Unspeci-Table I. ATM forum QoS classes QoS class QoS parameters Application 0 Unspeci"ed &Best e!ort', &At risk' 1 Speci"ed Circuit emulation, CBR 2 Speci"ed VBR video/audio 3 Speci"ed Connection-oriented data 4 Speci"ed Connectionless data Link utilization-based congestion detection has su!ered from either low utilization or an excess cell loss which is unacceptable in most data applications.