A next-generation optical regional access network

We describe an optical regional access network which combines electronic IP routing with intelligent networking functionality of the optical WDM layer. The optical WDM layer provides such networking functions as network logical topology reconfiguration, optical flow switching to offload traffic and bypass IP routers, wavelength routing of signals, protection switching and restoration in the optical domain, and flexible network service provisioning by reconfigurable wavelength connectivity. We discuss key enabling technologies for the WDM layer and describe their limitations. The symbiosis of electronic and optical WDM networking functions also allows support for heterogeneous format traffic and will enable efficient gigabit-per-second user access in next-generation Internet networks     

A management and visualization framework for reconfigurable WDM optical networks

As the phenomenal advance in optical WDM networking technologies continues, optical WDM network equipment has been deployed not only in backbone networks, but also in regional, metropolitan, and access networks. It is widely believed that a major component of the next-generation Internet will be an IP-based optical network employing WDM. WDM wavelength routing and signaling have become an active research field, and dynamic and adaptive wavelength routing and assignment algorithms have been proposed. However, there is less work on reporting network control and management system implementation efforts over testbed WDM networks. This article presents a network management and visualization framework aimed at guiding the development of management applications for reconfigurable WDM optical networks. A layered framework architecture including element and network management and visualization is provided, and an object-based information model representing the WDM network is introduced. Functional components on reconfiguration, software agent, and network visualization services are presented, and important issues related to optical lightpath generation are discussed. A network visualization service also provides WDM control and management APIs to applications and access networks such as an IP network management system. To illustrate the usage of the framework, we share our experience in implementing the MONET network control and management system, and present network visualization views obtained from the MONET WDM network to highlight the framework features.     

Architecture and Engineering Issues in Building an IP over WDM Networks

The technologies of IP over WDM have presently received increasing attention owing to the rapid growth in Internet traffic and the need for next-generation Internet technologies. The challenge now is how to integrate the services of IP over WDM optical networks to take full advantages of WDM technologies and IP technologies, and yield a high-throughput optical platform directly underpinning next generation data networks. This article discusses some of the architecture and technology issues for the design of IP over WDM optical networks.     

CATZ: Time-Zone-Aware Bandwidth Allocation in Layer 1 VPNs

The layer 1 virtual private network framework has emerged from the need to enable the dynamic coexistence of multiple circuit-switched client networks over a common physical network infrastructure. Such a VPN could be set up for an enterprise with offices across a wide geographical area (e.g., around the world or by a global ISP). Additionally, emerging IP over optical WDM technologies let IP traffic be carried directly over the optical WDM layer. Thus, different VPNs can share a common optical WDM core, and may demand different amounts of bandwidth at different time periods. This type of operation would require dynamic and reconfigurable allocation of bandwidth. This article evaluates the state of the art in layer 1 VPNs in the context of globally deployable optical networks and cost-efficient dynamic bandwidth usage. While exploiting the dynamism of IP traffic in a global network in which the nodes are located in different time zones, we study different bandwidth allocation methods for setting up a worldwide layer 1 VPN. We propose and investigate the characteristics of a cost-efficient bandwidth provisioning and reconfiguration algorithm, called capacity allocation using time zones (CATZ)     

用MPLS技术实现IP over WDM

提出了一种全新的高速宽带组网技术－基于MPLS的IPoverWDM网络技术,并对其进行了深入研究。这个方案在光联网技术中综合了目前先进的MPLS流量工程控制技术,特别适合于由可重构的OADM和OXC组成的以数据业务为核心的互联网络系统,而且它为最终在IP路由器上直接提供WDM复用功能铺平了道路。     

Performance and testbed study of topology reconfiguration in IP over optical networks

With the widespread deployment of Internet protocol/wavelength division multiplexing (IP/WDM) networks, it becomes necessary to develop traffic engineering (TE) solutions that can effectively exploit WDM reconfigurability. More importantly, experimental work on reconfiguring lightpath topology over testbed IP/WDM networks is needed urgently to push the technology forward to operational networks. This paper presents a performance and testbed study of topology reconfiguration for IP/WDM networks. IP/WDM TE can be fulfilled in two fashions, overlay vs. integrated, which drives the network control software, e.g., routing and signaling protocols, and selects the corresponding network architecture model, e.g., overlay or peer-to-peer. We present a traffic management framework for IP over reconfigurable WDM networks. Three "one-hop traffic maximization"-oriented heuristic algorithms for lightpath topology design are introduced. A reconfiguration migration algorithm to minimize network impact is presented. To verify the performance of the topology design algorithms, we have conducted extensive simulation study. The simulation results show that the topologies designed by the reconfiguration algorithms outperform the fixed topology with throughput gain as well as average hop-distance reduction. We describe the testbed network and software architecture developed in the Defense Advanced Research Projects Agency (DARPA) Next Generation Internet (NGI) SuperNet Network Control and Management project and report the TE experiments conducted over the testbed.     

IP over DWDM光互联网技术

对基于ＩＰ ｏｖｅｒ ＤＷＤＭ的新型数据网络体系结构－－光互联网络技术进行了探讨。在分析了三种构造未来信息网络解决方案的基础上,着重对基于ＩＰ ｏｖｅｒ ＤＷＤＭ的光互联网络的关键技术、光互联网的网络结构等内容进行了研究。     

集成化的光因特网技术

未来的光网络在体系结构复杂程度方面必须降低,以便节省费用和便于管理。将IP构建于光层上无疑是正确的解决办法。通用多协议标记交换(GMPLS)技术的出现,为光因特网的实现提供了一种新的方式。分析了IP层与WDM层的组网模型,基于GMPLS技术,建立了新的集成化的光因特网网络体系结构,分析和讨论了基于GMPLS的光因特网的控制平面的特征。研究结果为实现光因特网提供了一种新方法。     

Application, design, and evolution of WDM in GTS's pan-Europeantransport network

A pan-European transport network must cope with enormous traffic inflation by introducing appropriate network solutions. WDM technology is the solution adopted by GTS, driven by capacity requirements, infrastructure availability, flexibility, and cost. The deployment of this new technology presents specific technical issues, but more important, it lays the foundation of future optical networking. We describe the motives underlying the deployment of WDM technology in the long-haul and short-haul areas of GTS's operational transport network. Next, after presenting the use of WDM as the multiservice platform for SDH and IP overlay networks as well as native WDM services, we focus on the design of SDH-over-WDM and IP-over-WDM networks. Finally, we discuss future WDM networking and management requirements to better serve the needs of a pan-European carrier such as GTS     

IP over WDM光网络联合保护策略

随着Internet和网络技术的发展,IP over WDM光网络成为下一代通信网最理想的解决方案。因此,IP over WDM光网络的生存性是下一代通信网成功与否的关键。在传统的保护策略中,IP层和WDM层之间不交换网络的状态信息。探讨了IP层和WDM层保护机制互相协作的必要性,并在通用多协议标签交换GMPLS的基础上,提出了联合保护策略的思想。     

Planning of WDM Ring Networks

The rapid introduction of wavelength division multiplexing (WDM) technology to cope with the increased bandwidth requirements of transmission networks has intensified the need for recovery mechanisms at the optical layer. A first step towards survivable optical networking will be seen through the introduction of optical rings. This paper presents different types of optical rings (dedicated and shared protection WDM rings) and the planning issues associated with these WDM rings. In particular, we give mathematical models as well as solution methods for the ring loading and wavelength assignment problem. We compare the wavelength requirement of dedicated and shared protection rings under scenarios with different demand patterns. We also discuss the influence of the WDM equipment cost, and present a mathematical model for the optimization of hybrid networks with both dedicated and shared protection rings.     

Techniques for optical packet switching and optical burst switching

Wavelength-division multiplexing appears to be the solution of choice for providing a faster networking infrastructure that can meet the explosive growth of the Internet. Several different technologies have been developed so far for the transfer of data over WDM. We survey two new technologies which are still in the experimental stage-optical packet switching and optical burst switching-and comment on their suitability for transporting IP traffic     

Differentiated integrated QoS control in the optical Internet

In order to facilitate convergence of networks and services, this article investigates a new hybrid and integrated QoS control scheme that combines electrical IP layer features with reconfigurable optical layer, and addresses cross-layer design on QoS control in optical Internet (i.e., IP/WDM networks). The proposed integrated QoS control scheme can not only provide appropriate transport service for various types of traffic relating to different service categories in a cost-effective way, but also maintain high flexibility/scalability for integrated services provisioning, which seems to be preferred for QoS provisioning in the next-generation multiservice integrated optical Internet.     

The NGI ONRAMP test bed: reconfigurable WDM technology for nextgeneration regional access networks

Next generation internet optical network for regional access using multi-wavelength protocols (NGI ONRAMP) is a pre-competitive consortium sponsored by DARPA. Its mission is to develop architectures, protocols, and algorithms for wavelength division multiplexing (WDM)-based regional access networks that will effectively support the NGI. A reconfigurable WDM test bed is being built to demonstrate some of the key thrusts of the consortium, including dynamic service provisioning and optical flow switching, service protection in the optical domain, medium access control protocols, and network control and management geared for the efficient transport of Internet traffic over WDM networks. The ONRAMP test bed will consist of a feeder network connecting via access nodes to distribution networks on which the end users reside. ONRAMP network reconfiguration is enabled by access nodes that contain both optical and electronic switching components, allowing data traffic to be routed all-optically through the network or to be switched and aggregated by electronic Internet protocol (IP) routers. This paper describes the goals and basic architecture of the ONRAMP test bed, as well as the design, construction, and characterization of the network access nodes. To illustrate test bed operation, we demonstrate optical flow switching over the test bed that achieves Gb/s throughput of TCP data between end user workstations     

Architectural Options for the Next-Generation Networking Paradigm: Is Optical Internet the Answer?

Recent advances in optical networking technologies are setting the foundation for the next-generation data-centric networking paradigm, an “Optical Internet”. This work addresses one of the most challenging issues facing today's service providers and data vendors; how will the SONET/SDH-based legacy infrastructure currently in place make a graceful transition to the next generation networking paradigm?

A simplified, two-tiered architecture that requires two types of sub-systems will set the stage for a truly optical internet: service delivery platforms that enforce service policies; and transport platforms that intelligently deliver the necessary bandwidth to these service platforms. If IP can be mapped directly onto the WDM layer, some of the unnecessary network layers can be eliminated, opening up new possibilities for the potential of collapsing today's vertically layered network architecture into a horizontal model where all network elements work as peers to dynamically establish optical paths through the network. This paper presents a balanced view of the vision of the next-generation optical internet

The work presented here builds on the IETF multi-protocol lambda switching (MPλS) initiative and addresses the implementation issues of the path selection component of the traffic-engineering problem in a hybrid IP-centric DWDM-based optical network. An overview of the methodologies and associated algorithms for dynamic lightpath computation is presented. Specifically, we show how the complex problem of real-time provisioning of optical channels can be simplified by using a simple dynamic constraint-based routing and wavelength assignment (RWA) algorithm that compute solutions to three sub-problems: (a) routing; (b) constrained-based shortest-route selection; (c) wavelength assignment.

We present two different schemes for dynamic provisioning of the optical channels. The two schemes use the same dynamic lightpath computation approach proposed here, except that the third component, that is the wavelength assignment algorithm and its implementation, is different for each of the two schemes.

     

Storage area networking – an introduction and future development trends

This paper presents a detailed overview of the current and future networking options within the storage arena. Particularemphasis is placed on exploring strategic storage solutions, which are based on metropolitan area network (MAN) deployments,with respect to market influences, transmission evolution, and mediation. Evolution of storage networking is moving towards aconnecting role between multiple SAN islands and enterprise networks, across geographically dispersed networks. Thisconnection-based role can be typically over WANs or MANs and can be achieved in a number of ways – dark fibre point-topoint,ATM/SDH circuits and WDM. This paper focuses on what are believed to be the key technologies and evolutionary trends inthis area, and discusses storage-based issues relating to optical networking, WDM, SDH, ATM, as well as connectivity over IP.     

Survivability in a new pan-European carriers' carrier network basedon WDM and SDH technology: current implementation and futurerequirements

A pan-European carriers' carrier network, like other carrier networks, must cope with the enormous traffic inflation by introducing appropriate network solutions. WDM technology is the solution adopted by GTS Carrier Services' Trans European Network unit (TEN, formerly known as Hermes Europe Railtel), driven by bandwidth requirements, infrastructure limitations, flexibility, and cost. The introduction of such new technology presents specific technical issues, although it lays the foundation of future optical networking. Network outages are an important concern since, by using WDM, tens of gigabits of data are transported on each fiber. On one hand, traffic interruption is avoided as much as possible through secure fiber routings, cable protection, high design and equipment standards, and security. On the other hand, network protection techniques are used to limit the impact on services when inevitable outages occur. We explain the role of the different technologies in TEN's network. We concentrate on WDM and optical networking where optical channels are used to interconnect the equipment used by the different technologies. We focus on optical network protection techniques and illustrate that a clear requirement exists for this. We also emphasize interworking issues that come into play when multiple technologies are combined in the same network. It is not the intent to discuss only future requirements, but also to explain how the different aspects are currently implemented in TEN's operational network     

Connection management for multiwavelength optical networking

This paper describes the connection management research done by the Network Control and Management (NC&M) task force under the multiwavelength optical networking (MONET) program. MONET is sponsored by the Defense Advanced Research Project Agency (DARPA) the US Government Department of Defense, with participation from Bellcore, AT&T, Lucent Technologies, several government agencies, and regional Bell operating companies. MONET's vision is to develop a flexible reliable high-capacity high-performance cost-effective national optical network based on multiwavelength fiber optic technology. As an important component in realizing this vision, the MONET program includes the architecture and design of a prototype network control and management system for MONET's reconfigurable wavelength-division multiplexing (WDM) all-optical network. The primary objectives of the prototype research work are to develop the architecture and framework for managing national-scale transparent reconfigurable WDM optical networks and to demonstrate the feasibility of the NC&M prototype system in a field experiment network in Washington, DC. This prototype system allows the program participants to conduct experiments and gain experience in the management and operations of reconfigurable optical networks. This paper describes the connection management aspects of the prototype system, addressing issues such as the management architecture, information model, and provisioning algorithms of the prototype management system     

Architectures and performance of optical packet switching nodes for IP networks

As new bandwidth-hungry Internet protocol (IP) services are demanding more and more capacity, transport networks are evolving to provide a reconfigurable optical layer in order to allow fast dynamic allocation of wavelength-division-multiplexing (WDM) channels. To achieve this goal, optical packet-switched systems seem to be strong candidates as they allow a high degree of statistical resource sharing, which leads to an efficient bandwidth utilization. In this paper, we propose an architecture for optical packet-switched transport networks, together with an innovative switching node structure based on the concept of per-packet wavelength routing. The traffic performance of such node when loaded by a typical IP traffic is evaluated through computer simulation; packet loss probability and average delay performance are shown for various load conditions.     

可变带宽光网络：提出、优势和关键技术

新型互联网业务迅速发展。使网络流量急剧增长,推动了对光通信容量的需求。同时,新型的互联网应用对带宽的需求具有不可预测性。这两方面因素驱动光网络朝着灵活、动态、高效的方向发展。可变带宽光网络可以在收发端根据传输距离、链路质量、业务需求动态调整传输速率、调制格式以匹配网络实际需求,提高了网络灵活性和网络生存性。可变带宽光网络关键技术包括可变带宽可重构光分插复用器、可变带宽收发机技术、可变带宽的电层技术和可变带宽管控层技术。