A simple and efficient ABR control algorithm for large-scale networks

✍ Scribed by Ryoichi Kawahara; Toshihisa Ozawa

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 383 KB
• Volume: 83
• Category: Article
• ISSN: 8756-6621
• DOI: 10.1002/(sici)1520-6424(200009)83:9<44::aid-ecja5>3.0.co;2-f

✦ Synopsis

A simple and efficient available-bit-rate (ABR) control algorithm is described that fairly allocates bandwidth to each virtual channel (VC) in large-scale networks. In ABR control, the peak cell rate (PCR) and minimum cell rate (MCR) are specified at call set-up, and the cell-emission rate of each VC is controlled between them based on the explicit rate (ER) calculated from the traffic conditions at the ATM switches. Conventional control algorithms that do not use per-VC accounting allocate the same ER to all VCs. Therefore, if there is a VC with a PCR lower than the allocated ER, the control algorithm may not utilize the bandwidth effectively. A VC with an MCR higher than the allocated ER may suffer persistent congestion. Furthermore, algorithms that do not use per-VC accounting cannot achieve weighted bandwidth allocation. However, it is hard to implement algorithms that do use per-VC accounting in large-scale networks. The described ABR control algorithm makes it possible to maintain high throughput under PCR/MCR constraints and to achieve weighted bandwidth allocation based on the traffic conditions, without using per-VC accounting.