Standards for metropolitan area networks

The differences between local area networks (LANs) and metropolitan area networks (MANs) are outlined, and their impact on MAN standards is explored. The discussion covers IEEE P802's view of metropolitan area networks, MAN architecture, early proposals considered by the IEEE 802.6 committee, fiber optic proposals, and the emerging consensus. The need for field experience and the anticipated timetable for the IEEE P802.6 standard are also examined     

Evolution of metropolitan area networks to broadband ISDN

Broadband architecture and network evolution strategies based on interface standards emerging from the IEEE 802.6 MAN Committee and the American National Standards Institute (ANSI) T1S1 and CCITT Working Groups on broadband integrated services digital networks (BISDN) are outlined. The recent history of both the MAN and BISDN standards activities is traced, and some of the motivations behind specific developments are discussed. In the context, local area networks (LANs) and MANs are compared and contrasted, with special attention given to requirements specific to a public MAN. The convergence of the MAN and BISDN protocols is examined. The benefits of commonality between these two standards are described in terms of lower-cost network architectures, and terminal equipment is examined. It is shown that broadband networks can exploit the synergy between 802.6-based MANs and wider-area BISDN networks, and that 802.6-based MANs can gracefully evolve into countrywide networks using BISDN asynchronous transfer mode (ATM) switching. Example networks are used to illustrate the evolution proposals     

Topological design of interconnected LAN/MAN networks

The authors describe a methodology for designing interconnected LAN/MAN networks with the objective of minimizing the average network delay. They consider IEEE 802 standard LANs interconnected by transparent bridges. These bridges are required to form a spanning tree topology. The authors propose a simulated annealing-based algorithm for designing minimum delay spanning tree topologies. In order to measure the quality of the solutions, a lower bound for the average network delay is found. The algorithm is extended to design the overall LAN/MAN topology consisting of a MAN or high-speed data service interconnecting several clusters of bridged LANs. Comparison with the lower bound and several other measures show that the solutions are not very far from the global minimum     

SOJOURN TIME ANALYSIS OF DQDB MAN FOR LANs INTERCONNECTION

The Distributed Queue Dual Bus(DQDB) Metropolitan Area Network(MAN) is a promising solution for the evolution from current networks to B-ISDN. The performance of the DQDB MAN for Local Area Networks(LANs) interconnection is analyzed. The effects of message length, traffic load of upstream and downstream nodes and the parameters of bandwidth balancing mechanism and network counters on the sojourn time of message in the buffer are investigated, which present a valuable reference for the implementation of the DQDB MAN.     

High bandwidth metropolitan area networking architecture

The evolution of optical transmission media and laser technology has made bandwidth an abundant commodity rather than a scarce one. This factor has been clearly recognized by the communications community. As a result metropolitan area networks have been described by some as an extension of local area networks, with the major distinction being that MANs cover a larger distance than LANs. There are several limitations to the approach of simply extending LAN technology to the MAN environment. In this paper a new perspective on MAN architecture is provided that differs from the evolving LAN architecture.     

Issues and approaches on extending Ethernet beyond LANs

Currently, LAN technology is predominantly Ethernet-based and offers packet-optimized switched technology. With more than 90 percent of Internet traffic originating from Ethernet-based LANs, efforts are underway to extend Ethernet beyond LANs into MANs and further into WANs. However, native Ethernet protocols need extensions or support from other technologies in order to succeed as MAN technology in terms of scalability, QoS, resiliency, OAM, and so on. The two emerging trends to carry Ethernet traffic across the MAN can be classified into native Ethernet (IEEE) protocol extensions, and encapsulation by another transportation technology such as MPLS networks. The goal is to offer new and challenging services such as virtual private LAN service, also known as transparent LAN service (TLS). This article presents a comprehensive overview of the required extensions/support of the Ethernet with an emphasis on the emerging provider bridge technology.     

DQDB城域网实现计算机局域网互连时的性能分析

DQDB城域网是实现现有通信网络向B-ISDN过渡的优选网络。本文分析了DQDB城域网用于计算机局域网互连时的排队性能;研究了报文长度、网络上下游负荷、带宽平衡参数和网络计数器级数对报文在缓存器中停留时间的影响。所得结果可为DQDB城域网的具体实现提供参考。     

城域网标准—DQDB

局部网的飞速发展迫切要求在更大区域上进行互连,城域网正是为满足这种需求开发的。本文简要地叙述了IEEE802.6城域网的标准——分布排队双总线(DQDB)网的拓扑结构、网络节点的功能体系、帧格式和网络协议,最后分析了DQDB网的特性及其应用潜力。     

Gigabit local area networks: a systems perspective

A broad overview of gigabit local area networks (LANs) is presented from a systems perspective. Motivations and technical goals of gigabit LANs and challenges of coping with highly bursty traffic and large bandwidth mismatches between network links are described. The focus is on concerns unique to gigabit LANs, especially issues that differentiate them from gigabit wide area networks (WANs), metropolitan area networks (MANs), and lower-speed LANs. Major systems issues are discussed, and possible solutions, such as the virtual-connection architecture, are presented. The hardware technology required by gigabit LANs is illustrated by SONET components     

Wireless communications and networking: an overview

This paper presents an overview of wireless local-area networks (LANs) and wireless personal area networks (PANS), with emphasis on the two most popular standards: IEEE 802.11, and Bluetooth. While there are many such surveys in the current literature and online, we attempt here to present wireless LANs and PANS in a unified fashion as a viable alternative to wired LANs, while stressing the remaining challenges and limitations     

Multiaccess mesh (multimesh) networks

This paper introduces the multiaccess mesh (or multimesh) network. Stations are arranged in a two-dimensional (2-D) mesh in which each row and column functions as a conventional linear local-area network (LAN) or metropolitan-area network (MAN) subnetwork. Full connectivity is achieved by enabling stations to merge their row and column subnetworks, under the coordination of a merge control protocol. A two-dimensional token-passing protocol is considered, and a more complex protocol motivated by max-min fairness is also presented. Like conventional LANs and MANs, the multimesh requires no transit routing or store-and-forward buffering. The multimesh is a generalization of the token grid network. Using analysis and simulation, we study the capacity of multimeshes constructed of token rings and slotted rings, under uniform and nonuniform loads. A multimesh can support much higher throughput than conventional linear LAN and MAN networks with the same transmission hardware. Moreover, the multimesh capacity grows with the number of stations, We also present a healing mechanism that ensures full network connectivity regardless of the number of failed stations     

Fiber optic LANs for the manufacturing environment

The physical layer requirements for local area networks (LANs) that satisfy the set of environmental requirements unique to factory automation applications are discussed. In many cases these requirements are best met with fiber-optic LANs compatible with the IEEE 802.3 (CSMA/CD) or 802.4 (token bus) network standards. Implementation of a passive fiber-optic star-coupler-based LAN is presented in terms of two simple fiber-optic system design rules. A number of applications of the passive star-coupler-technology LAN are briefly described to highlight the benefits of fiber optics as a data communication medium     

A power line communication network infrastructure for the smart home

Low voltage electrical wiring has largely been dismissed as too noisy and unpredictable to support high-speed communication signals. Advances in communication and modulation methodologies as well as in adaptive digital signal processing and error detection and correction have spawned novel protocols capable of supporting power line communication networks at speeds comparable to wired LANs. We motivate the use of power line LANs as a basic infrastructure for building integrated smart homes, wherein information appliances ranging from simple control or monitoring devices to multimedia entertainment systems are seamlessly interconnected by the very wires that provide them electricity. By simulation and actual measurements using "reference design" prototype commercial powerline products, we show that the HomePlug MAC and PHY layers can guarantee QoS for real-time communications, supporting delay-sensitive data streams for smart home applications.     

一种新的局域网-ATM广域网连接方案

本文提出了一种新的局域网－ＡＴＭ广域网互连方案，它借助ＤＱＤＢ的排队策略对网络进行流量控制。该方案能够很好地保持信元的优先级，较好地按照传输请求的时序进行网络传输，并且有效地防止了ＡＴＭ缓冲区溢出。     

DQCA城域网实现计算机局域网互连时的性能研究

本文分析了分布式排队周期性访问ＤＱＣＡ城域网实现计算机局域网互连时的性能。通过比较研究发现，ＤＱＣＡ城域网在实现局域网互连时的性能（包括公平性能和报文停留时间）优于ＤＱＤＢ城域网。研究了网络参数Ｐｍａｘ、报文平均长度和报文统计特性对网络性能的影响。     

Rate-based head end controlled bandwidth allocation inundirectional bus metropolitan area networks

Future metropolitan area networks (MANs) will need a shared-medium backbone with capacity up to many gigabits per second to support the communication requirements of large numbers of users over distances of hundreds of kilometers. Efficient medium access control protocols for this future MAN environment are needed. The authors introduce and analyze a new protocol for unidirectional bus networks, in which bandwidth allocation and access fairness are adaptively controlled by the head end of the bus on the basis of traffic measurements. The proposed protocol can control the admitted traffic of a particular type to a desired fraction of the bus capacity and at the same time enforce access fairness faster than other existing protocols, such as the one used in the recently approved IEEE 802.6 MAN standard     

Integrated Services over ATM/MAN-Based Personal Communication Networks

IEEE 802.6 metropolitan area networks (MANs) providean efficient architecture for supporting wirelesspersonal communication services (PCSs) overmetropolitan areas by interconnecting wireless basestations into personal communication networks (PCNs).They also serve as peripheral gathering networks totransport PCS traffic over a wide area broadbandintegrated services digital network employingasynchronous transfer mode (ATM), enabling integrationof PCNs in different cities into a global PCN. Bycombining the various access methods and employing adynamic bandwidth integration scheme, a MAN canfunction as a powerful distributed switch forintegrating different types of local traffic.Simulation results are presented to illustrate theadvantages of the integration scheme. To provideubiquitous PCS, we also propose a simplesuffix-dialing method for integrating telephone, fax,paging and email services over the ATM/MAN-based PCNsusing a single personal telecommunication number. Withthis method, the current practice of printing a longlist of phone numbers on one's business card will nolonger be necessary.     

基于ASON的电力通信网演进策略

文章简要介绍了自动交换光网络(ASON)设备的应用现状、电力光传输网的网络结构、建设方式、业务类型和流向及存在的问题,指出了ASON适用于骨干/城域网的特点,并从网络规划设计、演进方式、ASON与传统光网络的互通和演进过程中需要注意的问题等方面简要阐述了电力通信网基于ASON技术的演进策略.     

802.6 MAN based personal communications network over CATV plants

An infrastructure shared 802.6 MAN based personal communication network(PCN) is to be discussed. Considering the network configurations of CATV and 802.6 MAN based PCNs, a possible architecture is proposed. It is shown that the unidirectional dual buses can be implemented over star topological CATV distribution cable networks with only two cores. The design considerations related to the network capacity and the signaling loads for wireless personal communications are investigated with numerical example. The MAN partitioning is considered to extend the capacity of the network. An analytical method to evaluate the signaling loads of 802.6 MAN based PCNs is presented with a new mobility model. It is shown that the signaling traffic increased by partitioning is not the critical constraint for the feasibility of 802.6 MAN based PCN     

Local-area networks go wireless

As standards emerge, data rates rise, and laptops seek connectivity, wireless LANs are finding a market niche as extensions to wired networks. Wireless LANs have found homes in buildings where installing wires would expose asbestos or destroy historic architecture. They have also proved valuable to companies that often relocate and want networks they can take with them. Another common use is for connecting wired LANs that are physically separated. The growth has been fueled by the desire to add wireless adjuncts to wired LANs, so that mobile workers can keep in constant contact with corporate networks over short distances. The author discusses the befits of wireless LANs. The radio based wireless LAN is discussed including multipath interference and data bottlenecks. The infrared based wireless LAN is also discussed and an inset discusses standards for wireless LANs