Centralized Flow Control Scheme for Rate-based Networks

Abstract

This paper describes the Centralized Flow Control Scheme (CFCS) for a network that uses rate-based flow and congestion control. An example of such a network is an Asynchronous Transfer Mode (ATM) network using the Available Bit Rate (ABR) service. CFCS is a centralized control scheme in which a Network Controller Switch (NCS) maintains the current information of the network such as the number of Virtual Circuits (VCs) active at each switch, available capacity at each switch and rate assigned for each active VC. In order to do this it maintains a Rate Allocation Table (RAT). In our scheme, NCS is the main network controller switch with enough processing power and other switches in the network are the switches without processing power and they do not execute flow control algorithm. We call such switches as Passive Switches (PAS). PAS are controlled by NCS. Thus, in this scheme, the NCS controls the overall operation of the network by allocating rates to ABR connections with the help of RAT. CFCS can achieve zero cell loss, high utilization of links, maintains fairness in allocating bandwidth, it reduces transient response time. Moreover, it needs less feedback information for control and need less parameter to set by users and network administrators. We show the effectiveness of our scheme by simulation experiments.