| ATM Networks are high speed networks with guaranteed quality of service. The main cause of congestion in ATM networks is over utilization of the physical bandwidth. Unlike constant bit rate traffic, the bandwidth reserved by variable bit rate (VBR) traffic is not fully utilized at all instances. Hence, this unused bandwidth is allocated to available bit rate traffic (ABR). As the bandwidth used by VBR traffic changes, available bandwidth for ABR traffic varies. In other words, available bandwidth for ABR traffic is inversely proportional to the bandwidth used by the VBR traffic.;To manage ATM networks efficiently, two new protocols are presented. A burst level admission control mechanism, Modified Fast Reservation Protocol, to avoid congestion by reserving bandwidth for long bursts of ABR traffic and a rate based congestion control algorithm, Explicit Allowed Rate Algorithm, based on the relationship between VBR and ABR traffic. Both these algorithms significantly improve the network throughput with minimal overhead on the switch. |
