In this paper, the rate-based congestion control algorithm that has been standardized in the ATM Forum is evaluated. Its behavior is analyzed by utilizing a firstorder fluid approximation to provide control parameter tuning. We obtain the maximum queue length at the switch and conditions for avoiding under-utilization. The results are then applied to TCP over ABR service class. More specifically, we evaluate the TCP-level performance through a simulation technique when TCP is applied to ABR service class with the rate-based congestion control. We first compare rate-based control of ABR service and EPD applied to UBR service, and show that rate based congestion control achieves better fairness and higher throughput in most circumstances. However, we demonstrate that rate-based control requires careful tuning of control parameters to obtain its effectiveness. I. INTRODUCTION In the ATM Forum, standardization effort has been devoted for the rate-based congestion control, which is aimed ...

A rate-based congestion control algorithm regulates cell emission rate of source end systems based on feedback information from the network. It was standardized by the ATM Forum for application to an ABR (Available Bit Rate) service class. In the standard, two types of congestion notification methods of the switch are specified: EFCI marking and explicit-rate marking. In this paper, we focus on explicit-rate marking switch. We propose our enhancements on a recently proposed switch algorithm called as the max-min scheme. The main objective of our enhancements is to control the queue length of the switch for preventing cell loss and achieving full link-utilization. We show effectiveness of our switch algorithm by simulation experiments. I. INTRODUCTION A rate-based congestion control algorithm is a closed-loop control method suitable for data transfer applications. In the rate-based congestion control algorithm, cell transmission rates of source end systems are regulated according to c...

this paper. Another approach may be to re-consider the congestion control mechanism of TCP to be suitably applied to the ABR service class. One example seems to be the Slow Start algorithm

Integrated Services Digital Network) that can transfer many types of multimedia information. In ATM-based networks, all information is transferred by dividing into fixed-size packets (called as cells). The ATM network is a connection-oriented network by virtue of a notion of virtual circuits called VPs (Virtual Paths) and VCs (Virtual Channels). The switch capability can be implemented in hardware because all information is transferred as fixed-size cells, and because cell routing at the switch is rather simple due to connection-oriented communication. For these reasons, the ATM technology is able to realize gigabit-class networks, which had been considered to be difficult with conventional packet-switching technology. To handle multimedia information effectively, five types of service classes are defined by the ATM standard bodies according to QoS (Quality of Services) requirements of various kinds of applications. At a connection setup, an application has to declare its traffic parameters and negotiates its QoS requirements with the network. However, since most of the existing applications such as data communications generate best-effort traffic, it is usually difficult for applications to predict their traffic patters. Thus, it has been an important issue how to accomodate best-effort traffic into ATM networks. Since best-effort traffic manages to utilize available resources