Packet-Switched Performance with Different Circuit-Switched Routing Procedures in Nonhierarchical Integrated Circuit-Switched and Packet-Switched Networks

It is shown in [13] that different types of routing procedures for circuit-switched traffic in a nonhierarchical network exhibit various performance tradeoffs. It is, however, not clear if the network is also allowed to carried packet-switched traffic, how the packet-switched traffic will be affected by using different routing procedures for the circuit-switched traffic. In this paper, we examine the average time delay of the packet-switched traffic assuming that the network uses a movable boundary scheme to allocate bandwidth dynamically     

Routing in multidomain networks

Investigates the problem of management and control in a large and, for simplicity, homogeneous packet-switched network. Specifically the authors focus on routing, an important function of network management. The network consists of several individually controlled domains. Domains are interconnected via gateway links. Each domain is controlled by its own network control center, while the overall network performance is managed by an integrated network control center. Each center has only a portion of the information required for global routing. The authors investigate the impact of the reduced information available at each center on network performance (average delay in the present case). They present a general approach to designing a hierarchical algorithm for routing in multidomain networks. They propose a heuristic procedure suitable for packet-switched networks. Several numerical examples illustrate the impact of incomplete information on the network. Performance is compared with a lower bound obtained, which is not differentiating destinations in other domains. Therefore, for this bound, each domain is perceived as a single node in a simplified model of the network     

Operational domains for circuit- and packet-switching

The performance of circuit-switched and of packet-switched networks are portrayed as surfaces in a three-dimensional evaluation space. The intersection of these surfaces defines two operational domains-one optimal for circuit-switching and one for packet-switching. This result is applied to network planning in future operational domains     

Capacity evaluation of packet-switched CDMA system

In this letter, an extended definition for packet-switched CDMA system capacity based on the protocol stack characteristics is proposed. According to the extended definition, the capacity of the packet-switched CDMA system for different ARQ protocols and different channel models is investigated. The results show that, compared with the traditional definition, the extended definition is more appropriate for describing the packet-switched CDMA network capacity     

Packet-switched WANs: more with less

During Operation Desert Storm, the US military used a packet-switched wide area network (WAN) to support the Army Central Forces Command and Control Information System (AC2IS) for the first time. The lessons learned from the difficulties encountered connecting a digital computer network using tactical signaling and switching equipment are outlined. The communications support which was available in Saudi Arabia, the AC2IS WAN configuration, and the performance of the packet switches used in the network are described. Operational statistics of circuit performance are presented     

演进的3GPP系统架构分析

3GPP在对无线接入演进的同时,相应地对系统架构进行了演进,称为SAE。SAE是一个全新的核心网络架构,它采用全分组IP方式,支持异构网络的接入和互通,具有良好的兼容性,同时简化了功能实体。对SAE的架构结构、功能实体以及功能实体之间的接口进行了介绍,同时对SAE中的策略控制计费控制技术以及接入系统之间的切换技术进行了分析。     

SIMNETMAN: an expert workstation for designing rule-based networkmanagement systems

The authors present SIMNETMAN, a network simulator, and discuss its role in exploring the utility of expert system technology for network management. SIMNETMANs companion system, NETMAN, is a collection of rule-based experts for network management. SIMNETMAN provides the user interface for NETMAN by allowing the experimenter to construct the network to be simulated, to specify the experiments, and also to modify the rules that comprise NETMAN, SIMNETMAN simulates a packet-switched network and actually conducts the experiments requested by the user. An overview of the system is presented, followed by a discussion of the implementation problems. The simulation capabilities of SIMNETMAN and preliminary performance results for the NETMAN/SIMNETMAN system are reported     

An all-IP approach for UMTS third-generation mobile networks

This article describes the UMTS all-IP approach for third-generation mobile systems, with emphasis on the core network architecture. Following the introduction of the core network nodes, we elaborate on application-level registration, circuit-switched call origination, packet-switched call origination, and packet-switched call termination.     

Real-Time Traffic Scheduling and Routing in Packet-Switched Networks Using a Least-Laxity-First Strategy

In this paper, we address the problem of transmission scheduling and buffer management at a switch in a high-speed packet-switched network. Future computer networks are expected to carry bursty real-time multimedia traffic with specific time-delay requirements. We propose a technique to schedule competing packets at a switch in a packet-switched network with two objectives—(i) maximizing the number of packets that would reach their destination before their deadline has been reached (ii) minimizing the number of packets dropped in transit in the network. The method is broadly based on the popular least-laxity heuristic in real-time process scheduling and is combined with buffer management at the switch.     

Isochronous communications in an integrated circuit/packetmetropolitan area network

A simple protocol is presented for establishing and terminating circuit-switched communications within a metropolitan area network (MAN) that supports both circuit-switched communication (for voice and video) and packet-switched communication (for data and file transfers). A mathematical model of the MAN is used to study its performance with respect to the circuit-switched communication and its effects on the pocket-switched communication. The models are numerically solved by the mean-value-analysis algorithm     

Optically transparent integrated metro-access network

High-capacity optical transmission technologies have made possible very high data rates and a large number of wavelength channels. Further, optical network functionality has made progress from simple point-to-point WDM links to automatically switched optical networks. In the future, dynamic burst-switched and packet-switched photonic networks may be expected. This paper describes a novel architecture of transparent WDM metropolitan area network (MAN) that is capable of switching on both packet-by-packet and burst-by-burst basis, thereby having the potential to achieve high throughput efficiency. The optically transparent MAN also includes a large part of the access network infrastructure. It is scalable, flexible, easy upgradeable and able to support heterogeneous network traffic. Some results of a preliminarly study on network performance are shown.     

A New Approach for Performance Evaluation of TCP over Interference-Limited Wireless Channels

A new metric for performance evaluation of transport control protocol(TCP) over wireless channels based on the interference-limited characteristics of code division multiple address(CDMA) system is proposed. According to the new metric, the performance of TCP over CDMA correlated channel for different protocol parameters and different versions is investigated. The results show that appropriate selection of protocol parameters and packet error rate(PER) operation point can improve significantly the capacity of packet-switched CDMA-based network.     

Performance comparison between optoelectronic and VLSI multistageinterconnection networks

The performance characteristics of optoelectronic and VLSI multistage interconnection networks are compared. The bases of the comparison include speed, bandwidth, power consumption, and footprint area. The communication network used in the comparison is a synchronous packet-switched multistage interconnection network built from 2×2 bit-serial switching elements. CMOS technology was used in the VLSI implementation, and it is assumed that the entire network resides on a single chip. Regular free-space optical interconnects are used in the optoelectronic implementation. The results show that for large networks optoelectronics offers higher speed and lower area than VLSI. Based on the assumed technology parameters, optoelectronics outperforms VLSI in bandwidth for network sizes above 256     

Cost-based scheduling and dropping algorithms to support integratedservices

Applications with diverse performance objectives must be supported on a single packet-switched network. The efficiency of such networks can be greatly improved through the use of sophisticated scheduling and dropping algorithms within the queues that form at the network access points and in switches throughout the network. In the present approach, arbitrary performance objectives are expressed in the form of cost functions, which map the queueing delay experienced by each packet to a cost incurred. The heuristic algorithms, cost-based scheduling (CBS) and cost-based dropping (CBD), then attempt to optimize network performance as perceived by the applications by minimizing the total cost incurred by all packets. Appropriate cost functions are presented for common applications. Scheduling and dropping algorithms are defined from these cost functions. It is demonstrated that network performance is better when these algorithms are used as opposed to the common alternatives. Also, contrary to conventional wisdom, some evidence is presented indicating that sophisticated scheduling may be preferable to sophisticated dropping as a means of adjusting loss rates     

SIP终端语音聊天的设计与实现

SIP协议是多媒体通信网的控制协议，在分组交换网中，它提供基本的呼叫控制，负责建立、修改和终止多媒体（话音、数据、视频等）会话等应用。概述了SIP终端软件的设计思想，并详细介绍了SIP终端软件中语音聊天功能的关键技术，从宏观和微观2个角度阐述了语音聊天功能的实现过程，构造了系统测试环境。SIP终端软件实现了语音聊天功能，具有良好的性能。     

分组网络中同步标准的进展及分析

如何解决同步信号地面链路传递问题,是目前分组传送网络中研究的一个重要课题。传统同步体系中的标准仅适用基于电路交叉技术的网络,并不适用于指导分组传送网络中面临的问题。目前虽已有运营商应用1588v2,满足移动回传网络中的时间同步需求,但随着网络复杂性的逐步增强,以及对设备时间(时钟)能力要求的不断提高,亟待相关标准的出台及完善。文章对分组网络中的同步标准进行了讨论,并就当前包交换技术实现频率和时间同步的热点应用给出了建议。     

Performance analysis of a hybrid DS/SFH CDMA system usinganalytical and measured pico cellular channels

This paper presents the throughput and delay analysis of a packet-switched code division multiple access (CDMA) network based on the hybrid direct sequence (DS)/slow frequency hopping (SFH) spread-spectrum multiple access (SS MA) technique with Q-, B-, and D-PSK modulation using analytical and measured pico cellular channels. The performance of the hybrid DS/SFH, DS, and SFH multiple access techniques have been compared in a pico cellular personal communications network (PCN) environment. Multipath and multiple access interference are considered. The performance is evaluated for a given delay spread and a fixed bandwidth. The effects of forward error correction (FEC) coding and diversity techniques, such as selection diversity and maximal ratio combining on the performance, are also investigated     

The evolution of transport network survivability

The bandwidth explosion ushered in by the popularity of the Internet has spurred the acceleration in the development and deployment of equipment supporting packet-based services. This-coupled with the widespread deployment of dense wavelength-division multiplexed systems in the core transport network to satisfy the corresponding increase in capacity demand-has led network planners to reconsider traditional approaches to network survivability. Existing architectures for transport network survivability were developed based on a ubiquitous circuit-switched/TDM network paradigm. As tariffed services increasingly migrate from circuit-switched/TDM to packet-switched/DWDM networks, survivability architectures must also evolve to meet the service requirements of this “new” packet-switched/DWDM network paradigm. We begin with an overview of existing strategies for providing transport network survivability, followed by an analysis of how the architectures for network survivability may evolve to satisfy the requirements of emerging networks     

Routing of multipoint connections

The author addresses the problem of routing connections in a large-scale packet-switched network supporting multipoint communications. He gives a formal definition of several versions of the multipoint problem, including both static and dynamic versions. He looks at the Steiner tree problem as an example of the static problem and considers the experimental performance of two approximation algorithms for this problem. A weighted greedy algorithm is considered for a version of the dynamic problem which allows endpoints to come and go during the life of a connection. One of the static algorithms serves as a reference to measure the performance of the proposed weighted greedy algorithm in a series of experiments     

A unified study of contention-resolution schemes in optical packet-switched networks

This paper presents a comprehensive study of contention-resolution schemes in a multiwavelength optical packet-switched network. This investigation aims to provide a unified study of a network of optical routers, which include contention resolution in wavelength, time, and space dimensions. Specifically, we show: 1) how to accommodate all three dimensions of contention resolution in an integrated optical router; 2) how the performance of the three dimensions compare with one another; and 3) how various combinational schemes can be designed and how they perform. With the representative architectures and network topologies studied in this paper, the simulation experiment results capture the characteristics of different contention-resolution schemes, and they quantify the upper-bound average offered transmitter load for these schemes. The combinational contention resolution schemes are shown to effectively resolve packet contention and achieve good network performance under light to intermediate load.