Generalized multiprotocol label switching: an overview of routingand management enhancements

Generalized multiprotocol label switching, also referred to as multiprotocol lambda switching, supports not only devices that perform packet switching, but also those that perform switching in the time, wavelength, and space domains. The development of GMPLS requires modifications to current signaling and routing protocols. It has also triggered the development of new protocols such as the Link Management protocol. We present the traffic engineering enhancements to the Open Shortest Path First Internet routing protocol and ISIS Intradomain Routing Protocol, two popular routing protocols, to support GMPLS. We present the concepts of generalized interfaces, label-switched path hierarchy, and link bundling intended to improve GMPLS scalability. We also discuss the Link Management Protocol which can be used to make the underlying links more manageable     

On the use of connection-oriented networks to support grid computing

The vision of grid computing is to enable an arbitrary set of general-purpose computers to be recruited dynamically and be interconnected through a general-purpose network for the parallel execution of complex programs. The scale and ubiquity of the Internet makes it the natural network of choice for grid computing. However, for some applications, rate- and delay-guaranteed communication services are needed. These needs are driving the exploration of connection-oriented (CO) optical networks as a candidate for grid computing. In this article, we consider the suitability of CO networks equipped with generalized multiprotocol label switching (GMPLS) control-plane protocols for grid computing. We identify two areas in which current GMPLS implementations need enhancements to better support the needs of grid computing. First, we note a need to improve call setup delays by several orders of magnitude. We describe our proof-of-concept prototype implementation of a hardware-accelerated RSVP-TE engine that cuts setup delays from hundreds of milliseconds (typical in current equipment) to the order of microseconds. Second, noting the availability of different types of CO networks, we present a case for enhancements to control "heterogeneous connections," that is, connections that traverse multiple types of CO networks. We describe a distributed signaling procedure for the setup of such connections.     

下一代IP技术--GMPLS

通用多协议标签交换 ,不仅支持实行分组交换的设备 ,也支持在时域 ,波长域和空间域进行交换的设备 .GMPLS的发展需要对现有的MPLS的信令和路由作出修改 ,也产生了新的协议。     

Challenges for GMPLS lightpath provisioning in transparent optical networks: wavelength constraints in routing and signaling - [Topics in optical communications]

GMPLS has introduced several enhancements to the MPLS-TE routing and signaling control plane protocols to handle dynamic lightpath provisioning in wavelength-routed networks. Specifically, the GMPLS signaling protocol has been enhanced to support two new provisioning functionalities, namely, the minimization of the setup delay, and the setup of bidirectional connection requests. In both cases, the source node must perform a wavelength allocation for either minimizing the setup delay (i.e., the suggested label) or requesting a bidirectional connection (i.e., the upstream label). However, these GMPLS provisioning functionalities present important deficiencies when applied to wavelength-routed networks with the wavelength continuity constraint, degrading the network performance considerably. The reason is that the standard GMPLS routing protocols flood link attributes only at bandwidth granularity, that is, no per-wavelength channel granularity is disseminated. Therefore, the source node is unable to perform an optimal wavelength assignment that fulfils the wavelength continuity constraint along the complete route toward the destination. In this article we present and experimentally evaluate an enhanced routing-based solution in the ADRENALINE testbed to handle the wavelength continuity constraint.     

Mesh network resiliency using GMPLS

The generalized multiprotocol label switching (GMPLS) is being developed as the control plane for the evolving photonic network. We describe how GMPLS can be used with mesh networks to provide efficient network resiliency. In particular we examine the key aspects of GMPLS that are used to support protection and restoration. We also study the various protection and restoration techniques, and we highlight the tradeoffs between recovery time and resource redundancy     

GMPLS协议中的路由和波长分配技术

因特网工程工作组（IETF）制定的通用多协议标签交换协议（GMPLS）,作为光网络的控制平面协议,推动了光网络的智能化进程。路由和波长分配问题（RWA）是光网络智能化的核心问题之一。在介绍RWA算法和GMPLS协议的基础上,分析了不同RWA算法、不同RWA机制对网络信息的需求,描述了GMPLS协议为解决RWA问题所做的标准化工作,并分析了与RWA相关的网络信息分发格式。     

Path vs. subpath vs. link restoration for fault management in IP-over-WDM networks: performance comparisons using GMPLS control signaling

We investigate three restoration techniques (path, subpath, and link restoration) for fault management in an IP-over-WDM network. We have implemented all of these techniques on the ns-2 simulation platform using generalized multiprotocol label switching (GMPLS) control signaling. These techniques can handle practical situations such as simultaneous multiple fiber failures, which are difficult to design for and recover from by nonrestoration techniques. We then present performance measurement results for the three restoration techniques by applying them to a typical nationwide mesh network running IP over WDM. We investigate interesting trade-offs in the performance of the restoration techniques on restoration success rate, average restoration time, availability, and blocking probability.     

Multilayer traffic engineering for GMPLS-enabled networks

In recent years, significant work has been completed on traffic engineering enhancements to the generalized multiprotocol label switching protocol suite (E. Mannie Oct 2004) (D. Katz et al., Sept. 2003) (K. Kompella et al., Oct 2003). As a next step, reproducing the current trend of switching layers' integration happening in the data plane, network control is foreseen to go beyond the traditional per layer approach and tend toward an integrated model (K. Shimoto et al., Oct 2004) (E. Dotaro et al., Dec. 2004). In these multilayer environments, a single GMPLS control plane drives various distinct switching layers at the same time and as a coherent whole, taking benefit from the "common" property of GMPLS. Beyond this application of supporting network control across different technologies, in this article we catalog the unified traffic engineering paradigms, discuss their applicability, and present their enforcement techniques. Furthermore, we show that the common GMPLS concept has the advantage of low operational complexity, and enables unified TE capabilities such as efficient network resource usage and rapid service provisioning.     

Reliable services in MPLS

MPLS (multiprotocol label switching) is a convergence of various implementations of IP switching using ATM-like “label swapping” to speed up packet forwarding without changes to existing IP routing protocols. An important practical issue is the capability to recover quickly from faults. We examine distributed methods for fast fault recovery using modified label distribution protocol messages. To maintain and verify service continuity, methods are proposed for traffic and performance monitoring     

Signaling and Control Procedures Using Generalized MPLS Protocol for IP over an Optical Network

This paper reviews the existing research activities on signaling and control procedures for IP over optical networks. We focus on the IP‐centric signaling and control architecture based on the generalized multi‐protocol label switching (GMPLS) protocol and analyze various scenarios and technical issues for deploying the IP over an optical network. We analyze the signaling and operations and administration and maintenance requirements for integrating an IP network and an optical network in order to cope with the high bandwidth and poor resource granularity of the optical network, including the optical cross‐connect system. On the basis of network architecture and a reference configuration model, we investigate the GMPLS‐based control architecture and interconnection model appropriate for controlling IP bandwidth and optical lambda resources. The signaling and control procedure based on GMPLS on optical user‐network interface and network‐network interface are comparatively investigated to provide the optical lightpath. We also study protection and restoration procedures to protect link failure when it applies to GMPLS signaling.     

通用多协议标签交换技术研究

通用多协议标签交换技术(GMPLS)在光交换网中具有广阔的应用前景,但对它的研究还不够深入.首先指出GMPLS与传统的标签交换技术(MPLS)在7个方面的区别,然后刻画GMPLS光网络的一般结构,对特点进行了分析,指出光IP包交换的实质是光标记的转发与交换.设计了GMPLS光网络的技术方案,对关键技术进行分析,提出了一...     

Experimental GMPLS-based provisioning for future all-optical DPRing-based MAN

Given the abundance and strategic importance of ring fiber plants in metropolitan area networks (MANs), and the accelerating growth of Internet traffic, it is crucial to extend the existing Internet protocol (IP)-based generalized multiprotocol label switching (GMPLS) framework to provision dynamic wavelength division multiplexing (WDM) optical rings. Nevertheless, the emerging GMPLS-based lightpath provisioning does not cover the intricacies of optical rings. No GMPLS standard exists for optical add-drop multiplexer (OADM) rings, relying instead upon proprietary static solution. The objective of this paper is to propose and evaluate novel GMPLS-based lightpath signaling and wavelength reservation schemes specifically designed for dedicated protection ring (DPRing)-based MANs. Performance evaluation has been carried out in a GMPLS-based testbed named ADRENALINE.     

Distributed virtual network topology control mechanism in GMPLS-based multiregion networks

This paper proposes a distributed virtual network topology (VNT) reconfiguration method for Internet Protocol over a wavelength-division-multiplexing network under dynamic traffic demand. We have developed a simple heuristic algorithm for calculating the VNT for distributed control. A generalized multiprotocol label switching (GMPLS)-based routing protocol has been developed. The VNT is quickly reconfigured by setting up and/or tearing down lightpaths using a GMPLS signaling protocol. Traffic demand is measured at the ingress node and advertised by the extended GMPLS routing protocol. Performance of the proposed method is investigated using variable traffic model.     

Resilience in GMPLS path management: model and mechanism

The recent advent of converging the IP and optical networks has necessitated the development of a generalized multiprotocol label switching framework. Resilience becomes more important than ever before in a GMPLS network since a single cut of an optical fiber may generate hundreds of link and node failures at high layers of the GMPLS architecture. In this article we briefly survey the current work regarding GMPLS recovery management, and present a new resilience-based dynamic GMPLS path management strategy. We present a simple model to represent the resilience requirements in GMPLS path management, and propose fast path management algorithms. The salient feature of the proposed approach is that it enables the paths to be dynamically selected under multiple simultaneous failure occurrences while satisfying the resilience requirement. Backup path design rules are developed, and the condition for backup path availability is derived for the special mesh-type GMPLS network. Finally, a simple example is shown to illustrate the effectiveness of the proposed resilience model and path management mechanism.     

GMPLS and ASON for automatic switched transport networks

In automatic switched transport networks (ASTN), transport services of different granularity can be set up, modified and released on demand, using mechanisms in the control plane. Currently, this novel provisioning paradigm is being standardized under the umbrella of the automatic switched optical network (ASON) and the generalized multiprotocol label switching (GMPLS) framework. This paper gives an overview of the concepts and open issues of ASON and GMPLS at the current stage of their development.     

Demonstration of the highly reliable Hikari router network based on a newly developed disjoint path selection scheme

Integration of multiprotocol label switching functions and multiprotocol lambda switching functions can enhance the throughput of IP networks and remove bottlenecks that are derived from electrical packet processing. To enhance the packet forwarding capability, NTT proposed a photonic MPLS concept that includes MP/spl lambda/S, and demonstrated IP, MPLS, and photonic MPLS integrated router systems called the photonic MPLS router. This router system is now called the Hikari router. The word Hikari is Japanese meaning beam, light, lightwave, optical, photonic, and sunshine. The amount of IP data traffic has grown remarkably. Massive IP routers and flexible route control mechanisms are now required to cope with the increased amount of traffic. The Hikari router can offer two solutions utilizing photonic switching technologies, and photonic network operation and management technologies. The first solution is utilizing photonic switching technologies realized using optical-switch-based crossconnect systems. The other solution is realized using the MPLS and MP/spl lambda/S signaling protocol and photonic network protection functions. In this article we report on the implementation of the Hikari router systems, propose a newly developed disjoint path selection scheme for generalized MPLS networks with shared risk link group constraints, and demonstrate the signaling protocol and network protection functions. The demonstration system achieves a distributed optical path set-up/tear-down protocol with an extended constraint-based routing label distribution protocol. Fast self-healing through automatic protection switching and a new restoration scheme are also implemented. These functions are successfully implemented, and the performance is verified on a demonstration network. The protection switching scheme achieves protection in less than 20 ms, and the optical path restoration scheme achieves restoration in less than 500 ms.     

Signaling Schemes for Distributed Connection Management in Wavelength-Routed Optical Mesh Networks

The next-generation optical transport network will evolve from point-to-point connectivity to mesh networking, which can provide fast and automatic provisioning with enhanced flexibility and survivability. Signaling is used to support connection setup, maintenance, and teardown in such a network. In this paper, we study the performance of two hop-by-hop and one parallel signaling schemes in wavelength-routed optical mesh networks. Based on the sequence between optical crossconnect (OXC) switching and signaling message processing, we classify hop-by-hop signaling into two types that comply with the requirements of GMPLS signaling protocols. These two types are forward before switching configuration (FBSC) and forward after switching configuration (FASC). Also, we propose a parallel signaling scheme that is different from the existing hop-by-hop GMPLS signaling protocols. Considering OXC architectures and traffic patterns, we compare the FBSC, FASC, and parallel signaling schemes using simulation experiments, in terms of network blocking probability and reservation time. The simulation data reveal that the performance of a signaling scheme depends on the nature of the signaling as well as the network setting (e.g., the OXC architecture and traffic pattern). We analyze reasons for this result and discuss tradeoffs between these signaling schemes. This work offers some insight into designing an efficient signaling protocol for wavelength-routed optical mesh networks.     

广义多协议标签交换GMPLS

未来的光传输网将由下列网络单元组成：路由器、交换机、DWDM系统、ADM、光交叉连接设备（OXC）等。为使由这些网络单元组成的网络具有很好的鲁棒特性,IETF的IPO工作组提出用广义的多协议标签交换（GMPLS）业动态地配置资源,充分利用保护和恢复技术提高网络的生存性,GMPLS将时隙、波长和光纤端口作为标签用于数据传发,由于各标签之间对应的数据粒度不同,GMPLS采用扩展的MPLS信令和路由来转发标签并建立相应的标签交换路径。     

Recovery of the control plane after failures in ASON/GMPLS networks

A reliable control plane plays a crucial role in creating high-level services in the next-generation transport network based on the generalized multiprotocol label switching (GMPLS) or automatically switched optical networks (ASON) model. Approaches to control-plane survivability, based on protection, and restoration mechanisms, are examined. Procedures for the control plane state recovery are discussed, including link and node failure recovery.