Performance Evaluation of a Traffic Control Mechanism for ATM Networks

Future ATM networks will be required to support a plethora of services, transaction types and cell sequence behaviors with performance guarantees. Before this goal can be realized, however, some basically problems related to bandwidth allocation and traffic control in the ATM layer must be resolve. Such problems will in all likelihood defy solution as long as they studied in isolation without a unifying traffic characterization and traffic control framework. This work presented in this paper is part of an ongoing effort directed at the development of an integrated traffic characterization and control infrastructure for ATM networks. In this paper a traffic control mechanism capable of monitoring and controlling a rich family of incoming traffic behaviors is introduced. The family of support traffic behaviors is clearly characterized. Some possible roles for the traffic control mechanism in a traffic control infrastructure are presented along with its detailed performance analysis. Finally, some new results on the stochastic behavior of a bursty source are presented

Optimal Burst Level Admission Control In A Broadband Network

In a broadband ATM network the traffic of a virtual circuit is defined at the cell, burst and call levels. All virtual circuits sharing the resources of a switch are statistically multiplexed at the cell level. In this paper the issue of how to control the admission of bursts of a particular virtual circuit is analyzed. It is demonstrated that under two optimization criteria, the optimal burst level admission control of a virtual circuit is a window control. This result suggests that while the cells of all virtual circuits sharing the resources of a switch should be serviced using the statistical multiplexing technique, at the burst level, the total number of bursts of a particular virtual circuit admitted inside the network should be monitored and controlled in such a way that the number of bursts does not exceed a given upper bound, which is the quota for that particular virtual circuit

Resource Allocation for Markovian Queueing Networks: The Partial Information Case

In this paper a resource allocation algorithm is presented for Markovian queueing networks operating under state dependent routing and flow control. The state of the network is described by the total number of packets in the network. In addition, in this paper, a new proof based on feasible direction techniques is presented for a classical result concerning Jacksonian networks. Specifically, the result states that for a Jacksonian network whose Norton equivalent is a concave increasing function with respect to the number of packets in the network, the optimal flow control is a window flow control with the random point, if it exists, at the end of the window. The result is proven for two distinct optimization criteria

Resource Allocation as Nash Game in a Multiclass Packet Switched Environment

We investigate the dynamical behavior of a decentralized network that is shared by users, each trying to achieve its own objectives

On the Effect of Delayed Feedback Information of Network Performance

The performance of a network subject to either state dependent or state independent flow control is investigated. In the state dependent case, the flow control policy is a function of the total number of packets for which the controller has not yet received an acknowledgment. In this case it is shown that the optimal flow control is a sliding window mechanism. The effect of the delayed feedback on the network performance as well as the size of the window are studied. The state independent optimal rate is also derived. The performance of the state dependent and state independent flow control policies are compared. Conditions for employing one of the two types of flow control policies for superior end-to-end network performance are discussed. All the results are demonstrated using simple examples

Real-time Admission Control Algorithms with Delay and Loss Guarantees in ATM Networks

A multimedia ATM network is shared by media streams with different performance requirements. For media streams such as file transfers, the preservation of bursts and the provision of guarantees for loss probability at the burst level is of primary importance, while, for media streams such as voice, loss guarantees at the cell level are sufficient. Continuous media have stringent delay jitter requirements. Finally, some applications require loss-free transmission. In this paper, the first complete traffic management scheme for multimedia ATM networks is introduced. The traffic management scheme supports four different classes of traffic, each of which has different performance requirements expressed in terms of delay jitter guarantees and cell or burst level loss guarantees. Its running time specification as well as its real time admission control algorithms are completely specified

Design of a Multimedia Applications Development System

The application envisaged for high speed packet switched networks have diverse and demanding transport requirements that are not satisfied by current communications software implementations. In addition, existing communication interfaces for distributed programs are not general enough to express the communication patterns and control required for distributed applications. This Multimedia Applications Development (MAD) system is designed to address these problems mentioned above. It is intended as a platform for implementing and experimenting with protocols and their implementation, network service access methods, and communication primitives for constructing distributed multimedia applications. It is expected that the research will yield real applications that can be used with a campus ATM environment, and that the results will provide deeper insights into how the communication needs of applications can be satisfied more effectively

The 3-Tier Structured Access Protocol to Control Unfairness in DQDB MANs

This paper addresses the unfairness problem appearing in 802.6-based DQDB MANs. Traffic load demand is characterized as low (below 0.4 of the channel capacity), normal (from 0.4 to 0.9 of the channel capacity) or heavy (greater than 0.9 of the channel capacity). At low loads the 802.6 protocol is acceptably fair. At normal loads, however, the protocol performance is markedly unfair. The unfairness is related to the latency in transporting a request. At heavy loads the unfairness is both latency-related and flooding-related. In this paper, both types of unfairness are carefully analyzed. As a control measure, a 3-Tier Structured Access protocol is proposed. At low loads the 802.6 performance is retained. For normal loads, extra slots are allowed based on predicted demand. At heavy loads access protection is applied. A Dynamic Assessment of Network Topology (DANT) protocol is also presented. The DANT dynamically maintains the additional information required for the implementation of the 3-tier structure. The proposed fair access protocol is studied under different load types and traffic demand. A tuning scheme is proposed to optimized the performance for a particular load environment in real time. The proposed protocol has the potential for dynamic bandwidth allocation and yields satisfactory performance

Performance Evaluation of a User Network Interface for ATM Networks

In this paper the functionality requirements of a user-network interface for bandwidth allocation are discussed. Such requirements include the capability to provide end users with a variety of non-deteriorating connection types. In addition effective policy enforcement and traffic shaping mechanisms are required to facilitate network management and the efficient utilization of network resources. Based on these requirements, a user-network interface model is proposed, and its performance is studied. Its intrinsic properties are revealed for two cases, a Poisson source and a bursty source

An Access Protection Solution for Heavy Load Unfairness in DQDB

This paper discusses the unfairness issue arising in a 802.6 DQDB network at high loads-- when the traffic demand to a bus exceeds the capacity of that bus. As per the 802.6 protocol, at heavy loads, the end nodes along a bus experience longer delays than the other nodes. The origin and remedy of this heavy load unfairness is discussed. An access control scheme is proposed as a solution. The comparison of the proposed scheme with 802.6 protocol is presented. The simulation results and performance characteristics are discussed under several types of loads. With symmetric load conditions under the proposed scheme, all active nodes along a bus experience almost the same access delay and packet loss characteristics. Performance under several other load condition are also found to be satisfactory