Congestion control scheme in ATM networks based on fast tracing-queue

One of the more challenging and unresolved issues in ATM networks is the congestion control of available bit rate （ABR）. The dynamic controller is designed based on the control theory and the feedback mechanism of explicit rates With the given method of a chosen parameter, it can guarantee the stability of the controller and closed loop system with propagation delay and bandwidth oscillation. It needs less parameters（only one） to be designed. The queue length can converge to the given value in the least steps. The fairness of different connections is considered further. The simulations show better performance and good quality of service（QoS） is achieved.

Performance and robustness analysis of a fuzzy-immune flow controller in ATM networks with time-varying multiple time-delays

For the Asynchronous Transfer Mode （ATM） networks with time-varying multiple time-delays, a more realistic model for the available bit rate （ABR） traffic class with explicit rate feedback is introduced. A fuzzy-immune controller is designed, which can adjust the rates of ABR on-line, overcome the bad effect caused by the saturation nonlinearity and satisfy the weighted fairness. Also, the sufficient condition that guarantees the stability of the closed-loop system with a fuzzy-immune controller is presented in theory for the first time. The algorithm exhibits good performance, and most importantly, has a solid theoretical foundation and can be implemented in practice easily. Simulation results show that the control system is rapid, adaptive, robust, and meanwhile, the quality of service （QoS） is guaranteed.

Binary ABR flow control over ATM networks with uncertainty using discrete-time variable structure controller

A binary available bit rate （ABR） scheme based on discrete-time variable structure control （DVSC） theory is proposed to solve the problem of asynchronous transfer mode （ATM） networks congestion in this paper. A discrete-time system model with uncertainty is introduced to depict the time-varying ATM networks. Based on the system model, an asymptotically stable sliding surface is designed by linear matrix inequality （LMI）. In addition, a novel discrete-time reaching law that can obviously reduce chatter is also put forward. The proposed discrete-time variable structure controller can effectively constrain the oscillation of allowed cell rate （ACR） and the queue length in a router. Moreover, the controller is self-adaptive against the uncertainty in the system. Simulations are done in different scenarios. The results demonstrate that the controller has better stability and robustness than the traditional binary flow controller, so it is good for adequately exerting the simplicity of binary flow control mechanisms.

A New Approach to VC Routing in ATM Networks

A new ant-algorithm-based routing approach is proposed for the VC routing problem with considering the comprehensive effect between the resource utilization and the load balance in ATM networks. In the approach, the backup paths are calculated first, and then an ant algorithm based on the ability of ants to find the shortest path between their nest and the food source during their searching food, is constructed to optimize the VC global route. Simulation results show that the proposed approach can realize VC routing effectively according to the current traffic states in the networks and the user-specified delay requirements.

Design of ATM Networks Congestion Controller Based on the Virtual Queue

The single bottleneck node of ATM networks is considered. The virtual queue mechanism and the method of proportion-integral-differential(PID) control are adopted in the congestion control. The sufficient condition of the considered system’s stability is given. The method of determining the PID parameters is given further. To quicken the speed of startup and remove the congestion rapidly, the factors of increase and decrease are set according to the length of queue. The result of simulation shows that the system, given an appropriate group of parameters, can acquire good robustness and dynamic performance, and guarantees the quality of service at the same time.

On the QoS for ATM Networks Using a New Buffer Utilization Technique

A buffer sharing scheme need to meet many competing objectives like robustness to changes in traffic conditions, fairness, efficiency, implementation simplicity, etc. Of the existing techniques, Push Out (PO) is optimum in terms of overall cell loss performance, but its delay performance is worse than that of all other methods for the multiple space priority. Another scheme named Dynamic Threshold (DT) is robust and adaptive which has good delay performance. A hybrid technique named Dynamic Threshold wi...

Hardware-in-the-loop simulation of communication networks

To enhance the fidelity and accuracy of the simulation of communication networks,hardware-in-the-loop（HITL） simulation was employed.HITL simulation methods was classified into three categories,of which the merits and shortages were compared.Combing system-in-the-loop（SITL） simulation principle with high level architecture（HLA）,an HITL simulation model of asynchronous transfer mode（ATM） network was constructed.The throughput and end-to-end delay of all-digital simulation and HITL simulation was analyzed,which showed that HITL simulation was more reliable and effectively improved the simulation credibility of communication network.Meanwhile,HLA-SITL method was fast and easy to achieve and low-cost during design lifecycle.Thus,it was a feasible way to research and analyze the large-scale network.

STUDY ON NEIGHBORHOOD DISCOVERY PROTOCOL IN COMMUNICATION NETWORKS

One algorithm and one method for PNNI(Private Network to Network Interface) routing were presented. The algorithm is OIL (Older Is Leader) algorithms for Peer Group selection, and the method is the DOO (Distributed object oriented) method for HDOS (Hierarchy Distributed Object System), PNNI systems and IP(Internet Protocol) networks. Based on the specifications from ATM forum, and the creative ideas from Distributed System realization, this paper studies and analyzes the private ATM network environment. The OIL algorithm and the DOO method are both for PNNI routing protocol. Through the PNNI simulation, the availability and robustness are proved for the above two improvements.

Connection Admission Control in ATM Networks Based on the Foreground and Background Neural Networks

Connection Admission Control(CAC)in ATM networks is the set o/actions taken by the networkto decide whether to accept connection requests during the phase of call establishment or call re-negotiation.CAC is an integral part of the preventive congestion control in ATM networks whose aim is to ensurenetwork performance.The CAC algorithm has the characteristics of the multitude of control parameters,high degree of computation complexity and strong time restrictions.In this paper we present a CACmechanism featured by combination of foreground control and background learning which is based onneural networks having the capabilities of self-learning and high-Speed processing.A case study is given,after which we discuss the practicability of the proposed algorithm.

Integrated VP-Based Control Strategies for ATM Survivable Networks

Nowadays the self-healing techniques in ATM networks are highly considered. However, in mostof networks, the normal control and sell-healing control are separately considered. In this paper, intenttedATM VP-based control strategies for ATM survivable networks are prOPosed, which combine the normalcontrol and self-healing control in a unified wad, being able to operate under both normal conditions andcatastrophic failure situations. These strategies allow a cost-effective network plan and design.

IP over ATM Implementation with Local Switch Mode

In classical IPOA, the communication of two users between local AsynchronousTransfer Mode (ATM) ports needs a VCC, however, it is not an elegant solution to the ATM accessequipments design when the performance of the whole system is considered. Thus, we investigate theway to provide the improved IPOA protocol that uses switching way in local ports. And it is fullycompatible with the CIPOA by using the same protocol for ARP and IP forwarding. In addition, we alsopresent the design of one 10/100 Mbit/s auto adaptive IPOA client board with local switch abilityidea and CAM mechanism for our project.

Comparative Study of Two Flow Control Mechanisms in High Speed Networks

Considerable protocol development efforts in recent ATM (Asynchronous Transfer Mode) Forum activities have been focused on the traffic management of available bit rate (ABR) service. It has been shown that ABR service enables persistent, greedy data sources to efficiently utilize ATM network resources with the help of a rate-based flow control mechanism. ATM Forum Traffic Management Specification Version 4.0 document gives a complete description of the end system behavior of the flow control mechanism, but it leaves the details of the switch behavior to be vendor-implementation dependent. For the sake of compatibility and interoperation among flow control mechanisms implemented by vendors, two rate-based mechanisms EPRCA (Enhanced Proportional Rate Control Algorithm) and ERICA (Explicit Rate Indication for Congestion Avoidance) have been recommended in the specification. In this paper, the mechanisms are studied and their performance is analyzed and compared with a material network. Simulation shows that ERICA is significantly better than EPRCA in the performance of steady state and instantaneous state of source end system ACR (Allowed Cell Rate) and buffer queue of bottleneck switch.

Multicast Tree Algorithm in ATM Network Environment

Computer networks are undergoing a remarkable transformation. The widespread use of optical fiber has tremendously increased network bandwidth. Furthermore, greater CPU power, increasing disk capacity, and support for digital audio and video are creating demand for a new class of network services. For example, video-on-demand (VOD), distant learning, distant diagnosis, video conferences, and many other applications have popped up one after another in recent years. Many of these services have one thing in common. They all require that the same data be sent to multiple recipients. Even in traditional networks, this operation, called multicasting, can not be handled easily and cheaply. When scaled up to high-speed ATM-based networks, the situation becomes more difficult. Multiple data streams travel around the ATM networks with each stream sent to many different destinations simultaneously. Therefore, the networks need a very efficient algorithm for multicast routing. This paper proposes an algorithm for multicast routing in ATM networks. The network routing cost is defined as the combination of the cost of establishing connections, the cost of overall bandwidth and the cost of overall switching. Our routing algorithm generates an optimal multicast routing with minimal overall network cost.

The model of transfer line and an adaptive congestion-oriented routing algorithm

A transfer line can be modeled as a linear system on maximal algebra. The model is also suitable to ATM and other rate-based communication systems. In respect to the rate-based speciality, a periodical input is considered as the system' s controller. Then some results in utilization, stability and congestion have been obtained. By use of them, we design an algorithm which integrates routing, resource allocation and flow control into a closed-loop architecture. It is adaptive and solves the prob-lem of congestion and uneven resource utilization. It also succeeds in controlling delay and delay jitter.