Asychronous transfer mode (ATM) networks are high-speed networks with guaranteed quality of service. The main cause of congestion in ATM networks is over utilization of physical bandwidth. Unlike constant bit-rate (CBR) tra$c, the bandwidth reserved by variable bit-rate (VBR) tra$c is not fully utilized at all instances. Hence, this unused bandwidth is allocated to available bit-rate (ABR) tra$c. As the bandwidth used by VBR tra$c changes, available bandwidth for ABR tra$c varies; i.e., available bandwidth for ABR tra$c is inversely proportional to the bandwidth used by the VBR tra$c. Based on this fact, a rate-based congestion control algorithm, Explicit Allowed Rate Algorithm (EARA), is presented in this paper. EARA is compared with Proportional Rate Control Algorithm (PRCA) and Explicit Rate Indication Congestion Avoidance Algorithm (ERICA), in both LAN and WAN environments. Simulation of all three algorithms are conducted under both congestion and fairness con"gurations with simultaneous generation of CBR, rt-VBR, nrt-VBR and ABR tra$c. The results show that, with very small over-head on the switch, EARA signi"cantly decreases the required bu!er space and improves the network throughput.

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 trle bandwidth used by VBR traffic changes, available bandwidth for ABR traffic varies, i.e., available bandwidth for ABR traffic is inversely proportional to the bandwidth used by the VBR traffic. Based on this fact, a rate based congestion control algorithm, Explicit Allowed Rate Algorithm (EARA), is presented in this paper. EARA is compared with Proportional Rate Control Algorithm (PRCA) and Explicit Rate Indication Congestion Avoidance Algorithm (ERICA), under congestion and faimess configurations. The results show that, with minimal overhead on the switch, EARA significantly decreases the required buffer space and improves the network throughput.

No abstract

Asychronous transfer mode (ATM) networks are high-speed networks with guaranteed quality of service. The main cause of congestion in ATM networks is over utilization of physical bandwidth. Unlike constant bit-rate (CBR) tra$c, the bandwidth reserved by variable bit-rate (VBR) tra$c is not fully utilized at all instances. Hence, this unused bandwidth is allocated to available bit-rate (ABR) tra$c. As the bandwidth used by VBR tra$c changes, available bandwidth for ABR tra$c varies; i.e., available bandwidth for ABR tra$c is inversely proportional to the bandwidth used by the VBR tra$c. Based on this fact, a rate-based congestion control algorithm, Explicit Allowed Rate Algorithm (EARA), is presented in this paper. EARA is compared with Proportional Rate Control Algorithm (PRCA) and Explicit Rate Indication Congestion Avoidance Algorithm (ERICA), in both LAN and WAN environments. Simulation of all three algorithms are conducted under both congestion and fairness con"gurations with simultaneous generation of CBR, rt-VBR, nrt-VBR and ABR tra$c. The results show that, with very small over-head on the switch, EARA signi"cantly decreases the required bu!er space and improves the network throughput.