ABR Flow Control Research Articles

Performance evaluation of ABR flow-control protocols in a wireless ATM network

Using an object-oriented simulation model of a basic client-server scenario in a wireless ATM network, we study the impact of handover and error-control protocols on the performance of high-speed data communication by the ABR service class. We present performance results of the ABR flow-control protocols ERICA and ERICA+ and discuss some implications for the protocol design.

Optimal structured feedback policies for ABR flow control using two-timescale SPSA

Optimal structured feedback control policies for rate-based flow control of available bit rate service in asynchronous transfer mode networks are obtained in the presence of information and propagation delays, using a numerically efficient two-timescale simultaneous perturbation stochastic approximation (SPSA) algorithm. Models comprising both a single bottleneck node and a network with multiple bottleneck nodes are considered. A convergence analysis of the algorithm is presented. Numerical experiments demonstrate fast convergence even in the presence of significant delays. We also illustrate performance comparisons with the well-known explicit rate indication for congestion avoidance (ERICA) algorithm and describe another algorithm (based on ERICA) that does not require estimating available bandwidth (as in ERICA).

The Impact of Handover Protocols on the Performance of ABR Flow‐Control Algorithms in a Wireless ATM Network

AbstractConsidering the high‐speed data transfer by the ABR service class in a wireless ATM network, we investigate the impact of forward and backward hard handover protocols on the performance of the three rate‐based ABR flow‐control schemes Explicit Rate Indication for Congestion Avoidance (ERICA+), Fuzzy Explicit Rate Marking (FERM) and a new promising adaptation of FERM, called FERMA. We evaluatc the performance of these flow‐control protocols by means of an object‐oriented simulation modcl of a basic client‐scrvcr architecture. Considering a standard hard handover protocol in a wircless ATM nctwork. wc show that our proposcd enhanced signaling schemes based on a congestion‐awarencssconceptand their integratibn into thc ABR flow control have a positive influence on the stability and efficiency of the cell transfer by ABR connections. Morcovcr, we point out that the new adaptation of the fuzzy‐control scheme FERM provides a promising altcrnativc lo the ERICA+ algorithm.

Multicasting flow control for hybrid wired/wireless ATM networks

Multipoint communication has been an increasingly focused topic in computer communication networks, including the Internet, the ATM, and the wireless/mobile networks. The major challenges of designing multicast flow control protocols for a combined wired/wireless network are the varying transmission characteristics (bandwidth, error, reliability, and propagation delay) of the wireless and wired media, and the irregular, different, possibly conflicting flow control requests from multiple receivers in the point-to-multipoint (branching) setting, or from multiple senders in the multipoint-to-point (merging) setting. To address these issues, in this paper we design, analyze, and evaluate both branch-point and merge-point algorithms; we also provide a comparison on the major issues and solutions of the two multicasting scenarios. On point-to-multipoint ABR flow control, we examine an existing max–min fair branch-point algorithm proposed by Siu and Tzeng, and formally analyze its maximum cell loss. A new algorithm is then proposed. Both the maximum cell loss and max–min fairness of new algorithm are analyzed. With extensive simulation, we compare three branch-point algorithms (including a third one proposed by Fahmy, Jain et al.). On multipoint-to-point flow control, we extend the “essential fairness” concept, which was first proposed by Wang and Schwartz to flow control of multicast and unicast TCP traffic in the Internet to the multipoint-to-point ABR flow control. We design a general switch algorithm, which provides essential fairness to the multipoint-to-point ABR flow control. Three major variations of the algorithm, each of them guarantees different fairness (of favor) to unicast or multicast sessions, are then presented. These three schemes are evaluated by simulation. The significance of our approach is illustrated by the formal analysis of cell loss, feedback delay and max–min fairness properties, the generalized fairness definition for multicasting flow control, and the comparisons we made for (1) point-to-multipoint vs. multipoint-to-point scenarios, (2) three branch-point algorithms, and (3) three fairness definitions and mechanisms of multipoint-to-point multicasting. The work may be applied to multicast services in various high speed networks, such as supporting differentiated multicast service over IP, supporting flexible billing schemes, and providing QoS services over hybrid networks.

The dual flow control problem of TCP over ATM ABR services

In this paper, we investigate the dual control problem—TCP flow control at the TCP layer and ABR flow control at the ATM layer. First, we observe that TCP flow control and ABR flow control cannot co-operate well. The worst case is that the slow start after packet loss causes high but unused ACR (Allowed Cell Rate) which raises the potential of cell loss and an underflowed switch queue which reduces ABR throughput. We suggest to implement a use-it-or-lose-it policy for ABR and fast recovery for TCP to avoid these phenomena. Copyright © 1999 John Wiley & Sons, Ltd.

Designing stable ABR flow control with rate feedback and open-loop control: first-order control case

In this paper we present a control-theoretic approach to design stable rate-based flow control for ATM ABR services. The flow control algorithm that we consider has the most simple form among all the queue-length-based flow control algorithms, and is referred to as first-order rate-based flow control (FRFC) since the corresponding closed loop can be modeled as a first-order retarded differential equation. We analyze the equilibrium and the asymptotic stability of the closed loop for the case of multiple connections with diverse round-trip delays. We also characterize the asymptotic decay rate at which the stable closed loop tends to the equilibrium. The decay rate is shown to be a concave function of control gain with its maximum being the inverse of round-trip delay. We also consider an open loop control in which the queue control threshold is dynamically adjusted according to the changes in the available bandwidth and the number of connections. This open loop control is shown to be necessary and effective to prevent the closed loop from converging to an undesirable equilibrium point.

TCP/IP traffic over ATM networks with FMMRA ABR flow and congestion control

In this paper, we study and compare the performance of TCP/IP traffic running on different rate based ABR flow control algorithms such as EFCI, ERICA and FMMRA by extensive simulations. The FMMRA algorithm is shown to exhibit the favorable features of least buffer requirement, fair bandwidth allocation to TCP connections, fast and accurate ACR rate adjustment according to the changes of network traffic, and the highest effective TCP throughput.

First-order rate-based flow control with dynamic queue threshold for high-speed wide-area ATM networks

In this paper we present a new rate-based flow control scheme for ATM ABR services and analyze its performance. The proposed algorithm, which we refer to as first-order rate-based flow control (FRFC) is the most simple form of queue-length-based flow control. The asymptotic stability, the steady-state throughput, queue length and fairness, and the transient behavior are analyzed for the case of multiple connections with diverse round-trip delays. We also consider a novel approach to dynamically adjust a queue threshold in the FRFC according to the changes in the available bandwidth, and the arrival and departure of connections. Simulations show that the simple FRFC with dynamic queue threshold (DQT) effectively maintains high throughput, small loss and a desired fairness in these dynamic environments and is a promising solution for ABR flow control in ATM networks.

Rate control algorithms for the ATM ABR service

AbstractOver the last couple of years both the ATM Forum and ITU‐T have converged on a closed‐loop, feedback based, rate control mechanism as the framework for the Available Bit Rate ATM Transfer Capability. In this framework, an ABR source adapts its transmission rate to changing characteristics of the ATM network by either testing periodically the state of the network or through direct feedback from the network. The state of the network is conveyed to the source either as a simple binary feedback signaling congestion or no congestion, or as an explicit rate indicating the rate at which the source can transmit. In this paper we review the detailed framework for the ABR service standardized by the ATM Forum, the underlying service philosophy and protocol design goals for ABR flow control, and the premises and high‐level performance characteristics for the more promising ABR rate control schemes proposed so far.