Network high availability for ethernet services using IP/MPLS networks

Enterprises are increasingly using Ethernet as the foundation for transforming their networks to Internet Protocol. Simultaneously, service providers are deploying Ethernet to exploit the demand for wide-area Ethernet services and as the infrastructure for new residential services such as IPTV. This is due to Ethernet's low cost per bit and ubiquity in local area networks. Recent years have seen the widespread deployment of IP/MPLS networks to address this opportunity. IP/MPLS enables enhanced flexibility over the same converged network for IP and legacy services, avoiding the need to build separate per-service networks. It also adds carrier- grade capabilities such as quality of service, traffic engineering, and resiliency, thereby enabling new multipoint services such as virtual private LAN service. However, using Ethernet for ";always-on"; and other mission-critical services has resulted in new resiliency requirements, in both the access and the network core. Two novel developments address these high expectations by enabling significant improvements in service availability. These are pseudowire redundancy and Ethernet multi-chassis link aggregation. This article reviews the current redundancy mechanisms typically deployed in Ethernet and MPLS networks. We show how additional enhancements are required in both the network core and the access to the Ethernet service. We describe new pseudowire redundancy and MC- LAG mechanisms, showing how they work together to enable end-to-end protection for Ethernet virtual private wire services and VPLS.     

Ethernet OAM: key enabler for carrier class metro ethernet services

The onset of Ethernet as a metropolitan and wide area networking, technology has driven the need for a new set of operations, administration, and maintenance protocols. Service provider networks are large and complex with a wide user base, and they often involve different operators that must work together in order to provide end-to-end services to enterprise customers. With enterprise end customer demands ever increasing, so have the requirements on service provider Ethernet networks increased, particularly in the areas of availability and mean time to repair. Ethernet OAM addresses these areas and more, and is a tool that translates directly to the competitiveness of the service provider. Ethernet OAM is a broad topic, but this article focuses on three main areas that are most in need by service providers and are rapidly evolving in the standards bodies: Service OAM, Link OAM and Ethernet LMI. These OAM protocols have unique objectives but are complementary to each other. Service OAM provides monitoring and troubleshooting of end-to-end Ethernet service instances, while link OAM allows a provider to monitor and troubleshoot an individual Ethernet link. There are of course many different ways to provide this type of functionality, but fortunately standards bodies such as ITU Study Group 13, IEEE 802.3 Clause 57 (formerly 802.3ah), IEEE 802.1ag Connectivity Fault Management, and the Metro Ethernet Forum are all driving toward consistent recommendations and standards for Ethernet OAM.     

LAN91C111型控制器在嵌入式以太网接口中的应用

嵌入式以太网不仅可用于工业现场实现现场节点的自动上网功能,而且还可以用于信息家电的以太网接口实现远程控制,具有很好的发展前景.文章介绍基于TMS320LF2407型DSP的嵌入式系统与LAN91C111型自适应10Mb/s/100Mb/s嵌入式以太网控制器的接口电路及软硬件实现方法.     

Reliable wide-area wavelength division multiplexing passive optical network accommodating gigabit ethernet and 10-Gb ethernet services

This paper proposes and demonstrates a reliable wide-area wavelength-division-multiplexing passive optical network (WDM-PON) with a wavelength-shifted protection scheme. This protection scheme utilizes the cyclic property of 2/spl times/N athermal arrayed-waveguide grating and two kinds of wavelength allocations, each of which is assigned for working and protection, respectively. Compared with conventional protection schemes, this scheme does not need a 3-dB optical coupler, thus leading to ensure the large loss budget that is suited for wide-area WDM-PONs. It also features a passive access node and does not have a protection function in the optical network unit (ONU). The feasibility of the proposed scheme is experimentally confirmed by the carrier-distributed WDM-PON with gigabit Ethernet interface (GbE-IF) and 10-GbE-IF, in which the ONU does not employ a light source, and all wavelengths for upstream signals are centralized and distributed from the central office.     

IsoEthernet: an integrated services LAN

IsoEthernet is an integrated services LAN directed at multimedia applications. It enables the carrying of 6.144 Mb/s of isochronous data (96 B-channels at 64 kb/s each) in addition to 19 Mb/s of 10Base-T traffic using the existing 10Base-T wiring infrastructure. A 10Base-T mode of operation accommodates existing 10Base-T equipment. Interoperability with 10Base-T networks is provided for packet traffic. IsoEthernet is being standardized by the IEEE 802.9 standards committee     

A routing architecture for mobile integrated services networks

A drawback of the conventional Internet routing architecture is that its route computation and packet forwarding mechanisms are poorly integrated with congestion control mechanisms. Any datagram offered to the network is accepted; routers forward packets on a best-effort basis and react to congestion only after the network resources have already been wasted. A number of proposals improve on this to support multimedia applications; a promising example is the Integrated Services Packet Network (ISPN) architecture. However, these proposals are oriented to networks with fairly static topologies and rely on the same conventional Internet routing protocols to operate. This paper presents a routing architecture for mobile integrated services networks in which network nodes (routers) can move constantly while providing end-to-end performance guarantees. In the proposed connectionless routing architecture, packets are individually routed towards their destinations on a hop by hop basis. A packet intended for a given destination is allowed to enter the network if and only if there is at least one path of routers with enough resources to ensure its delivery within a finite time. Once a packet is accepted into the network, it is delivered to its destination, unless resource failures prevent it. Each router reserves resources for each active destination, rather than for each source–destination session, and forwards a received packet along one of multiple loop-free paths towards the destination. The resources and available paths for each destination are updated to adapt to congestion and topology changes. This mechanism could be extended to aggregate dissimilar flows as well. This revised version was published online in June 2006 with corrections to the Cover Date.     

A unified wireless LAN architecture for real-time and non-real-timecommunication services

This paper addresses how to support both real-time and non-real-time communication services in a wireless LAN with dynamic time-division duplexed (D-TDD) transmission. With D-TDD, a frequency channel is time-shared for both downlink and uplink transmissions under the dynamic access control of the base station. The base station (1) handles uplink transmissions by polling mobiles in a certain order determined on a per-connection (per-message) basis for transmitting real-time (non-real-time) traffic from mobiles and (2) schedules the transmission of downlink packets. To handle location-dependent, time-varying, and bursty errors, we adopt the channel-state prediction, transmission deferment, and retransmission. We consider the problems of scheduling and multiplexing downlink packet transmissions, and polling mobiles for uplink transmissions depending on the channel state. We also establish conditions necessary to admit each new real-time connection by checking if the connection's delivery-delay bound can be guaranteed as long as the channel stays in good condition without compromising any of the existing guarantees. Last, the performance of the proposed protocol is evaluated to demonstrate how the protocol works and to study the effects of various parameters of the protocol     

Interoperability update: dynamic ethernet services via intelligent optical networks

This article describes the 2005 Worldwide Interoperability Demonstration held by the Optical Internetworking Forum and showcased during SUPERCOMM 2005, The event highlighted Ethernet services transported over intelligent optical networks, using equipment from 13 of the industry's leading vendors located in seven carrier laboratory facilities around the world. The demonstration utilized a distributed optical control plane based on OIF Implementation Agreements to control a multilayer network providing Ethernet over SONET/SDH adaptation and transport. The article describes the global test network, services, architecture, and overall test approach. It also describes innovations made to the optical control plane to handle multilayer signaling and lists further refinements needed to make these services operational.     

Packet communication protocol for image services on a high-speedmultimedia LAN

The authors describe the requirements for high-speed multimedia communication and propose a high-speed communication protocol to provide congestion-free access and efficient retransmission/flow control. Its usefulness is proved in a 400 Mb/s multiaccess loop local area network (LAN) with a 100 Mb/s user interface. The main characteristics of the protocol are separation of image communication handling, guarantee of no buffer overflow in a network, and end-to-end block-based transfer. Buffer reservation control in the user-network interface and a retransmission scheme based on a long-size block are used to realize high-speed congestion control and error recovery. A multimedia terminal architecture suitable for real-time image communication is also discussed. In the prototype system, a few frames of high-resolution image information can be transferred in a second. Around 26 Mb/s effective throughput between application entities has been obtained     

Proposal of networking by PON technologies for full and ethernet services in FTTx

The construction of optical access networks is one of key issues to provide new broad-band services and emulation of legacy services. Passive optical network (PON) technologies realize sophisticated and economical optical access networks for these purposes. This paper summarizes requirements and technical and marketing trends for optical access networks. It also presents advantages of networking by PON technologies for optical access networks. Moreover, it clarifies issues to install and operate PON base optical access networks and proposes solutions for these issues.     

面向多样化服务定制的多态路由机制研究

如何基于有限且确定的路由结构来支持多样化服务是当前研究面临的问题,采用路由结构的自组织和自调节来实现路由与业务的“自适配”,提出一种面向多样化服务定制的多态路由机制。该机制通过自适配网络路由结构的基本“微内核”,实现到个性化定制寻址路由结构的派生与重载,使网络具有动态适应多样化业务的路由服务功能,并且支持多样网络寻址与路由的多模多态共存。     

LAN interconnect using X.25 network services

The use of X.25 for medium-speed applications (<56 kb/s) in personal computer local area networks (LANs) is considered, focusing on a number of popular LAN-based applications that are appropriately matched for X.25 services. For architectural reasons, they are broadly classified into two categories: PC-to-host access (terminal emulation), as in token ring, to synchronous data link control (SDLC) hosts using host gateways; and client-server applications, such as distributed databases that are bridged or routed. For each class of applications, the traffic characteristics are discussed, it is explained how an efficient interconnection can be accomplished, and some insight is provided into how LAN internetworking devices (routers and gateways) function in an X.25 environment     

Optimized rule-based delay proportion adjustment for proportional differentiated services

We present a novel method to adjust output queue delay proportion fairly among traffic classes of different priorities in relative differentiated services. The delay proportion adjustment is based on acceleration of incoming traffic in each class. It aims to reduce the undesirable effects of queue-delay propagation toward higher priority classes, caused by the introduction of bursty data into lower priority classes. We use a fuzzy controller to make the decision regarding the amount of proportion adjustment, as it is very flexible and adjustable. We suggest an efficient extension to the particle swarm optimization algorithm for the purpose of optimizing the fuzzy system. The simulation shows that the dependency of high-priority-class delay, which is a value that indicates quality-of-service of the traffic, on lower priority classes is significantly reduced by the proposed delay proportion adjustment.     

A routing framework for providing robustness to node failures in mobile ad hoc networks

Nodes in a mobile ad hoc network are often vulnerable to failures. The failures could be either due to fading effects, battery drainage, or as a result of compromised nodes that do not participate in network operations. Intermittent node failures can disrupt routing functionalities. As such, it is important to provide redundancy in terms of providing multiple node-disjoint paths from a source to a destination. In line with this objective, we first propose a modified version of the widely studied ad hoc on-demand distance vector routing protocol to facilitate the discovery of multiple node-disjoint paths from a source to a destination. We find that very few of such paths can be found. Furthermore, as distances between sources and destinations increase, bottlenecks inevitably occur and thus, the possibility of finding multiple paths is considerably reduced. We conclude that it is necessary to place what we call reliable nodes (in terms of both being robust to failure and being secure) in the network to support efficient routing operations. We propose a deployment strategy that determines the positions and the trajectories of these reliable nodes such that we can achieve a framework for reliably routing information. We define a notion of a reliable path which is made up of multiple segments, each of which either entirely consists of reliable nodes, or contains a preset number of multiple paths between the end points of the segment. We show that the probability of establishing a reliable path between a random source and destination pair increases tremendously even with a small number of reliable nodes when we use our algorithm to appropriately position these reliable nodes.     

Addressing, bridging, and source routing [LAN interconnection]

The concept of source routing for the interconnection of local networks is described. An architectural framework is provided to emphasize the principal advantages inherent with such a bridging mechanism. Motivation for this form of routing is shown to be a consequence of the address structure within the local network standards that have been adopted by IEEE, the European Computer Manufacturers Association (ECMA), and the International Organization for Standardization (ISO). As with many internetworking protocols, the use of a qualified address structure allows a more efficient routing mechanism. The physical address of a station, although not explicitly present in each transmitted frame, is implied by its attachment to a specific segment of the local network. This subtle point relative to local network addressing provides the foundation for the incorporation of source routing protocols     

Time slot switching for integrated services in fiber optic PBX/LAN

A medium-access protocol called time-slot switching (TSS) is proposed for use in optical-fiber local area networks. This protocol incorporates features of time division, space division, and time compression for users to share a common medium. Very-large-integration (VLSI) CMOS electric crosspoints are used to switch traffic within individual time slots. With these features, data, voice, and video services can all be combined in a single network. In addition, the speed of the electronics can be maximized to match the available optical bandwidth. Operational principles of the TSS protocol are explained. A performance analysis is presented to show the tradeoffs among traffic capacity, frame guard time, blocking probability, and the results show that TSS is more attractive than broadcast protocols for voice traffic or constant-rate data traffic. An approach to integrating voice, data, and video traffic within TSS is also described     

A management and control architecture for providing IPdifferentiated services in MPLS-based networks

As the Internet evolves toward the global multiservice network of the future, a key consideration is support for services with guaranteed quality of service. The proposed differentiated services framework is seen as the key technology to achieve this. DiffServ currently concentrates on control/data plane mechanisms to support QoS, but also recognizes the need for management plane aspects through the bandwidth broker. In this article we propose a model and architectural framework for supporting DiffServ-based end-to-end QoS in the Internet, assuming underlying MPLS-based explicit routed paths. The proposed integrated management and control architecture will allow providers to offer both quantitative and qualitative services while optimizing the use of underlying network resources     

Optimized priority based energy efficient routing algorithm for mobile ad hoc networks

Recently more and more research interest focuses on the energy efficient routing in mobile ad hoc networks and many related routing algorithms are reported. In this paper, a new optimized priority based energy efficient routing algorithm is presented and priority is added to the existing routing algorithm according to the residual energy proportion of the nodes. Lower residual energy means lower priority and the nodes with lower priority are less likely to forward packets to other nodes. The algorithm needs no global information of the networks and only a little modification is needed to the existing algorithm, so it is practical to be implemented. The algorithm can improve the performance of routing discovery, routing maintenance and cache management at the same time. Some optimization strategy is taken to reduce the network overhead and the lifetime of the network is much longer and the network with our algorithm can transfer much more effective data. Simulation with NS-2 is done and satisfying results are obtained with this algorithm. The results show that the algorithm is efficient.