An Exact Explicit Rate Indication Scheme for each VC in ATM Networks

Abstract

The Asynchronous Transfer Mode (ATM) technique has been accepted as a basis for the future B-ISDN networks. With the B-ISDN/ATM goals of supporting diverse services and traffic mixes, and of efficient network resource engineering, the design of the traffic control becomes a difficult task. The ATM Forum has chosen the rate-based scheme as an approach to congestion control for the Available Bit Rate (ABR) services. So far, many rate-based congestion control schemes have been proposed. Some of them use the negative feedback rate control. Therefore, if all notification cells in backward direction experience extreme congestion, the overall network congestion collapse may happen. Others use the positive feedback rate control, but the unfair distribution of available bandwidth among Virtual Connections (VCs) may occur. To resolve the problems of the existing rate-based control scheme, in this paper, we propose a new congestion control scheme called Exact Explicit Rate Indication (EERI) scheme. In the EERI scheme, the network explicitly informs each source the exact rate they should transmit a message. The network determines the rate of each source based on the fair rate setting procedure. The rate determination mechanism doesn't require per-connection queuing or per-accounting in the network, which are considered expensive techniques with the current hardware technology. By using the Benchmark Fairness Configuration (BFC), we show that the proposed scheme can achieve an excellent fairness performance among connections existing in the network. Furthermore, in the EERI scheme there are not oscillations in the rate allocation. In the transient behavior, the EERI scheme offers fast access to available bandwidth, which is a sensible requirement particularly in the LAN and MAN environments.