Experimental demonstration of an improved EPON architecture using OFDMA for bandwidth scalable LAN emulation

We propose and demonstrate an improved Ethernet passive optical network (EPON) architecture supporting bandwidth-scalable physical layer local area network (LAN) emulation. Due to the use of orthogonal frequency division multiple access (OFDMA) technology for the LAN traffic transmission, there is no need to change the existing EPON architecture. Only one receiver at each optical network unit (ONU) is required to detect both LAN traffic and EPON downstream traffic, which makes the proposed system simple and cost-effective. Moreover, flexible assignment of LAN traffic bandwidth is realized by allocating different number of subcarriers or using different modulation formats. The 250 Mb/s 4-quadrature amplitude modulation (4-QAM) and 500 Mb/s 16-QAM OFDM LAN traffic are successfully emulated with the EPON traffic in our experiment.     

Provider link state bridging

Wide area communications technology has been challenged to virtualize large numbers of Ethernet LAN segments. This is a consequence of a mismatch between the broadcast nature of the LAN segment and the extremely constrained connectivity implied by the p2p connections or tunnels available in the WAN environment, which have been combined to create virtual LAN segments. PBB-TE has been a practical demonstration of how filtering applied to a broadcast media can result in a connection. This article introduces provider link state bridging (PLSB), which adds a control plane to the PBB data plane in order to extend the techniques for manipulation of Ethernet bridges for unicast paths pioneered by PBB-TE. PLSB solves the problem of largescale virtualization of LAN segments over an Ethernet infrastructure by applying advances in computation performance to the multicast capabilities inherent in the Ethernet data plane. The result is that the fundamental primitives of connectivity today, the broadcast LAN segment and the connection, can be virtualized in a scalable manner on a common (but substantially larger and better utilized) Ethernet-based infrastructure.     

Secure data transmission in extended Ethernet environments

An extended Ethernet LAN is built by connecting several Ethernet segments by means of suitable devices (repeaters, bridges, etc.). A common way to make this interconnection is through a main segment, called the backbone, that joins each of the departments (or, perhaps, building floors) within the owner premises. In this kind of network, data transmission in the backbone is very sensitive to either eavesdropping or manipulation. The implementation of a cryptographic system that protects transmission (providing for both confidentiality and integrity of transmitted data) in this kind of network is addressed. The operation of the proposed system and the specific troubles encountered in implementing it in the local network of the Polytechnic University of Catalonia are presented. An analysis of the functionality of the ciphering bridges is provided and their implementation is studied in detail. Finally, the more relevant results and conclusions are given     

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.     

一种生成VLAN帧的模块的设计

VLAN(Virtual LocalArea Network)是一种通过将局域网的设备逻辑地而不是物理地划分为一个个网段,从而实现虚拟工作组的新兴技术。不同的VLAN内部的广播和单播流量都不会转发到其他VLAN中,从而有助于控制流量、减少设备投资、简化网络管理、提高网络的安全性。本文介绍了一种VLAN帧的生成模块的设计方案,其中包括VLAN插入、剥离、MAC地址的更新与还原以及重写FCS位等。通过对大量相关资料的分析,最后用Verilog-HDL语言成功地对电路进行了设计。     

A novel medium access control protocol for passive optical network supporting local area networking capabilities

An alternate solution for Ethernet passive optical networks (EPON) providing local area networking (LAN) capabilities is proposed in this article. Our solution adopts a star coupler-based PON architecture and uses radio frequency subcarrier multiplexed transmission for the LAN traffic delivery. The proposed medium access control (MAC) protocol supports a fully distributed control plane among the optical network units (ONUs) for ONU–ONU communication as well as upstream access to the OLT. The simulation results indicate that the proposed MAC protocol outperforms the others in terms of the average packet end-to-end delay, especially for LAN traffic.     

Optical Network Design for a Multiline-Rate Carrier-Grade Ethernet Under Transmission-Range Constraints

Ethernet is a success story in local area networks (LAN). Efforts for extending its boundaries beyond LAN to the carriers' backbone networks are in progress. We study the problem of designing reliable and cost-efficient high-rate (100 Gbit/s) carrier-grade Ethernet in a multiline-rate optical network under signal transmission-range constraints. Reliability is achieved using shared-path protection at the connection level (Ethernet tunnel in this study). We construct an auxiliary graph, called mixed topology (MT), using which it is possible to: 1) identify traffic grooming possibilities; 2) select a path which requires the minimum amount of 3R regeneration; and 3) effectively choose the data rate of the channel to be established. Our algorithms, tested on the 17-node German network, resulted in lower network cost and higher resource utilization compared with other schemes.     

Optimized routing for providing ethernet LAN services

Ethernet's-move into metropolitan and wide area networks is driving a rapidly growing market opportunity. Current Ethernet services come in two basic flavors, Ethernet line and LAN, providing point-to-point and multipoint connectivity, respectively. The LAN services, although more cost effective, are lagging behind in deployments due to associated QoS and bandwidth provisioning issues. The Ethernet service provider needs to provision the network to meet current and future traffic demands, where the traffic is unpredictable and bursty. The goal is to minimize. overprovisioning and complexity. To add to the challenge, Ethernet routing is based on simple self-learning and relies on spanning tree routing. In this article we propose an Ethernet-specific load balanced routing mechanism, which is robust to dynamic traffic demand. It significantly reduces overprovisioning, is simple and static, and requires only bandwidth profiles associated with service level agreements at the ingress and egress links. Our simulation results show that our scheme provides performance improvements over a recently proposed approach for switched Ethernet as well as a related load balancing approach for Ethernet over MPLS networks.     

Design and evaluation of an Ethernet-based residential network

When the information superhighway arrives at the neighborhood, a residential network will connect home appliances to the community access network. These appliances include personal computers, printers, and video clients. Among all local-area network (LAN) protocols, Ethernet is the most economic and the most popular. The unique characteristics of residential networks call for new performance studies. A residential network typically has few nodes and runs different applications than business and academic LANs. Consequently, residential networks have traffic characteristics different from the subject of existing studies. We constructed a residential network testbed to collect typical application traffic statistics. Additional live traffic characterization was obtained from campus networks. Also, we investigated the suitability of Ethernet for video distribution through simulation. This paper discusses the design issues for residential networks and presents a network design that is based on Ethernet technology. Traffic models are established from the actual traffic traces and used for the performance evaluation of residential networks. Furthermore, several future data traffic scenarios are considered with bandwidth up to 6 Mb/s by scaling up current data traffic. The simulation results of the performance suggest that Ethernet can be used as a cost-effective residential network for video and data communications     

Next generation local area networks

Many people now consider the local area network (LAN) to which their desktop personal computer (PC) is attached to be more important to them than the telephone network, resulting in a drive to increase both the performance and the reliability of LANs. This paper examines the key drivers for new LAN technologies, summarising LAN developments over previous years. It then looks at possible options for future LANs, which will need to evolve to meet changing traffic patterns brought about by widespread use of intranets and multimedia applications. This encompasses both new technologies such as Gigabit Ethernet, and new architectures such as virtual LANs (VLANs), multi-protocol over ATM (MPOA) and multi-protocol over LANs (MPOL).     

光纤以太网技术在城域网中的应用

光纤以太网网是指在光纤上运行以太网局域网（LAN）数据包接入服务的网络，底层连接可以以任何标准的以太网速度运行，包括10Mbit/s、100Mbit/s、1Gbit/s或10Gbit/s。光纤以及网把以太网技术扩展到LAN之外，进入城域网（MAN）。光纤以太网也将以太网的优越性扩展到了MAN，大大降低了运营商的网络建设成本。     

Self-similarity through high-variability: statistical analysis ofEthernet LAN traffic at the source level

A number of empirical studies of traffic measurements from a variety of working packet networks have demonstrated that actual network traffic is self-similar or long-range dependent in nature-in sharp contrast to commonly made traffic modeling assumptions. We provide a plausible physical explanation for the occurrence of self-similarity in local-area network (LAN) traffic. Our explanation is based on convergence results for processes that exhibit high variability and is supported by detailed statistical analyzes of real-time traffic measurements from Ethernet LANs at the level of individual sources. This paper is an extended version of Willinger et al. (1995). We develop here the mathematical results concerning the superposition of strictly alternating ON/OFF sources. Our key mathematical result states that the superposition of many ON/OFF sources (also known as packet-trains) with strictly alternating ON- and OFF-periods and whose ON-periods or OFF-periods exhibit the Noah effect produces aggregate network traffic that exhibits the Joseph effect. There is, moreover, a simple relation between the parameters describing the intensities of the Noah effect (high variability) and the Joseph effect (self-similarity). An extensive statistical analysis of high time-resolution Ethernet LAN traffic traces confirms that the data at the level of individual sources or source-destination pairs are consistent with the Noah effect. We also discuss implications of this simple physical explanation for the presence of self-similar traffic patterns in modern high-speed network traffic     

Efficient multicasting and broadcasting in layer 2 provider backbone networks

Ethernet has grown from its roots in LANs to contend in previously unchartered territory of MANs and WANs. A slew of projects underway in the IEEE 802 standards bodies plan to groom Ethernet with carrier grade features like high availability, fault management, and resiliency thus far found only in other circuit-switched technologies. These include, among others, IEEE 802.1ag (connectivity fault management), IEEE 802.1ad (provider bridges), and IEEE 802.1ah (provider backbone bridges). IEEE 802.1ah addresses the service and MAC address scalability of provider backbone bridges. Since Ethernet has been architected and designed for a shared medium, it inherently handles broadcast and multicast traffic very efficiently, unlike layer 3 technologies, where multicasting and broadcasting rely on using multiple point-to-point connections. With IEEE 802.1ah, Ethernet would be able to provide millions of service instances in a provider backbone network. While flooding of frames in a LAN may provide for good multicasting, flooding of data in a MAN or WAN could mean huge bandwidth wastages, especially when the remote peers are geographically distant, and the traffic is not necessarily destined to any of its local ports of the peers. In this article we explore technologies to Address efficient multicasting in provider backbone networks. We also consider extending this technology to address unknown unicast floods and efficient proxy of customer multicast frames.     

基于OPNET交换式局域网仿真建模与分析

常规局域网存在信道利用率不高、时延较大的问题,用户迫切需求使用一种方便快捷、性能良好的网络。针对这一问题,提出了常规局域网的一种改进方式---交换式局域网（ Switching LAN）。介绍了OPNET仿真软件的主要特性、建模机制及仿真步骤。采用OPNET网络仿真软件设计实验,根据2种网络特点建立不同的场景并进行仿真,并通过对比以太网时延、接收数据包流量、数据包冲突数目在不同场景时的变化,证明了交换式局域网的性能明显优于常规局域网。     

基于POWERPC823的嵌入式视频网络接入系统的研究

嵌入式视频网络接入终端是针对监控、电信、交通、银行等领域的监控产品。视频网络接入终端可将经编码器压缩后的视频信号直接以多播的方式送上局域网(10M／100M以太网)。本文叙述了阐述了系统的工作原理、研究方法、研究成果。     

The road to carrier-grade ethernet - [Topics in optical communications]

Carrier-grade Ethernet is the latest step in the three-decade development of Ethernet. This work describes the evolution of Ethernet technology from LAN toward a carrier-grade operation through an overview of recent enhancements. After reviewing native Ethernet and its transport shortcomings, we introduce the major carrier-grade upgrades. We first discuss the evolution of layer-2 architectures. Then, we detail the service specifications and their QoS and traffic engineering requirements. Finally, we describe the new OAM and resilience mechanisms.     

The fibernet II ethernet-compatible fiber optic LAN

Fibernet II is a fiber-optic local area network (LAN) having an active-star configuration. It is plug compatible with the 10- Mbit/s coaxial-cable Ethernet LAN at its transceiver cable interface. Ethernet requires the detection of packet collisions; this function is implemented in Fibernet II at the active star node. Collision presence is signaled to the host transceivers with a unique in-band optical signal. Fibernet II features improved electromagnetic immunity, absence of signal radiation from cables, freedom from ground-loop currents due to ground potential differences between remote sites, new network topology options, and a growth path to future broad-band services. This paper describes the Fibernet II experimental system as implemented at the Xerox Palo Alto Research Center. A space-time analysis is presented which confirms that Fibernet II can support a network diameter of over 4.0 km, in contrast to the coax Ethernet which is limited to 2.5 km.     

Ethernet passive optical network (EPON): building a next-generationoptical access network

This article describes Ethernet passive optical networks, an emerging local subscriber access architecture that combines low-cost point-to-multipoint fiber infrastructure with Ethernet. EPONs are designed to carry Ethernet frames at standard Ethernet rates. An EPON uses a single trunk fiber that extends from a central office to a passive optical splitter, which then fans out to multiple optical drop fibers connected to subscriber nodes. Other than the end terminating equipment, no component in the network requires electrical power, hence the term passive. Local carriers have long been interested in passive optical networks for the benefits they offer: minimal fiber infrastructure and no powering requirement in the outside plant. With Ethernet now emerging as the protocol of choice for carrying IP traffic in metro and access networks, EPON has emerged as a potential optimized architecture for fiber to the building and fiber to the home     

IEEE 802.11 Wireless LAN: can we use it for multimedia?

The IEEE P802.11 committee developed the 802.11 Wireless LAN standard to cover wireless networks for fixed, portable, and moving stations within a local area. This standard addresses the need for wireless connectivity to stations, equipment, or automatic machinery that requires rapid deployment and may be portable, handheld, or mounted on moving vehicles. It can function totally wireless or connected to a wired network. Most people familiar with the standard expect to use it in providing wireless networks for personal computers or stations connected to the global wired infrastructure through access points. Now that the 802.11 standard is finally here, it will energize the wireless LAN market and result in the proliferation of low cost wireless connectivity in the office and home. Study groups are working on higher rates at 2.4 GHz and at 5 GHz for future inclusion into the standard. These higher rates will make it even more practical to employ this standard for multimedia traffic