In this paper, we propose the window-based congestion control mechanism using explicit feedback in TCP over ATM ABR service. The proposed scheme is based on notifying the network status as the free buffer length at the congested link to the IP station which informs the window rate by modifying the receivers' advertised window field in TCP ACK returning to the source. Results from simulation show that our proposed algorithm improves the fairness and stability of TCP connections in general network environments even if they have the different round trip times.

The major concern at a branch point in asynchronous transfer mode (ATM) networks for point-to-multipoint available bit rate (ABR) services is how to consolidate backward resource management (BRM) cells from each branch for a multicast connection. In this paper, we propose an efficient feedback consolidation algorithm based on an adaptive dynamic threshold (ADT) to eliminate consolidation noise and to reduce consolidation delay. The main idea of the ADT algorithm is that each branch point estimates the ABR traffic condition of the network through virtual queue estimation. Simulation results show that the proposed ADT algorithm can achieve a faster response in congestion status and a higher link utilization compared with the previous works.

This letter proposes a congestion control scheme for the ABR service of ATM networks which have non-responding connections. The control scheme is robust with respect to both the round trip delay and the loss of control information caused by non-responding connections. Thus, it is shown that the proposed control scheme guarantees the QoS of the network.

In this study, we propose a branch-point scheme for multicast ABR service in ATM networks. The performance of the proposed scheme is obtained to show that the consolidation noise and delay can be reduced more effectively than those of the existing schemes.

One of the objectives of ABR traffic control is a fair allocation of transmission rate to every connection. Algorithms which have been proposed can achieve the fair allocation of transmission rate in persistent traffic, even though the connections have different number of hops. In bursty traffic, however, the transmission rate during the burst period, called average burst throughput, may become degraded when the number of hops increases. In this paper, we evaluate the average burst throughput characteristics of ERICA switch algorithm and investigate the effect of the number of hops. We propose a new bandwidth allocation method which can improve the performance degradation by taking the number of hops into account. The effectiveness of our method is evaluated by computer simulation.

A new approach for the flow control of available bit rate service in ATM network is proposed using supervisory control theory upon discrete event models. According to the approach, each rate controller adjusts the input source traffic within a specific zone decided by the supervisor. In this way, the proposed control scheme ensures congestion avoidance and the maximal successful transmission rate of the input source traffic in a fair manner upon a simplistic way of explicit rate setting for resource management cells.

Both available bit rate (ABR) service and unspecified bit rate (UBR) service with early packet discard (EPD) schemes have been considered for supporting data applications in ATM networks. Since transmission control protocol (TCP) is perhaps the most widely used transport layer protocol in existing data networks, the performance of TCP over ATM using ABR service and UBR service with EPD schemes is of great interest to ATM equipment vendors and service providers. In this paper, we present a simulation study of this interesting issue in a LAN environment using some benchmark network configurations proposed in the ATM Forum. Our simulation results show the following: (1) With UBR service and EPD schemes, TCP suffers significant performance degradation in terms of fairness and requires relatively large switch buffer even with a small number of active virtual connections over a LAN configuration, and (2) for the same set of network configurations and with ABR service using explicit rate feedback schemes, TCP achieves good performance in terms of fairness and link utilization, and requires relatively small switch buffer.

A novel reactive congestion control scheme based on Dynamic UPC/NPC (Usage/Network Parameter Control) in ATM networks is proposed. In this scheme, policing parameters at the UPC/NPC are dynamically modified in response to the reception of RM (Resource Management) cells. In a congested state, traffic volume submitted to the network is regulated by Dynamic UPC/NPC, while providing negotiated QoS (Quality of Service) for each ATM connection. When end-stations (or edge-entities between network segments) operate according to ER-based (Explicit Rate based) behavior, a UPC/NPC function will indicate (send) an ER value toward each source end-station using backward RM cells. In this case, the policing parameter at the UPC/NPC should take the same value as the ER value. When end-stations (or edge-entities) operate according to EFCI-based (Explicit Forward Congestion Indication based) behavior, the modified policing parameter at the UPC/NPC point must be harmonized with the modified cell transmission rate at the source end-stations (or at the edge-entities). In order to improve the control performance for the long distance connections, backward RM cells will be generated by the NPC function (UPC function will be optional) at the egress of a congested network in response to the reception of EFCI marked cells (or forward RM cells) as a proxy destination end-station, and they will be sent back toward the UPC/NPC function at the ingress of the network. As a result, the proposed control scheme enables the network to recover from the congested state securely and provide the negotiated service quality, even if cooperation of (rate-based) flow control at each source end-station (and at edge-entities between network segments) is not expected.