ASON控制平面探究

本文主要针对自动交换光网络ASON的核心部分一控制平面进行研究.从ASON的结构切入,论证了控制平面的引入是ASON具有智能性的必要条件.GMPLS技术作为最易于实现控制平而的方法,讨论了RSVP-TE中LSP的连接、删除和状态刷新.对GMPLS生存机制中故障LSP的4中恢复方式的通道建立及恢复时间进行了分析和比较,从而得出资源预留综合考虑下是现阶段最优的恢复方式的结论,并对单点故障时各恢复方式在连接影响和业务丢失率方面进行相互比较,突出预置重路由的特点:恢复速度快,网络恢复能力的可预见性好.     

利用ASON控制平面技术改造传统光网络设备

通过对智能光网络的网络结构和相关技术的分析,提出了一种对传统光网络设备进行智能化改造的新技术.该技术通过构建一个运行于EMS和传统光网络传输设备之间的"机顶盒"设备,来实现控制平面的基本功能."机顶盒"依据EMS指定的相关参数,计算满足业务要求的子网内端到端的显式路径;并且通过RSVP-TE信令建立LSP连接,为业务建立承载通路.该技术融合了网络管理、信令、路由等协议,能够实现光网络设备的平滑升级,降低风险,节省资金投入.     

基于RSVP-TE的组播信令协议在ASON中的实现

讨论了自动交换光网络中实现组播的意义,介绍了GMPLS框架下基于RSVP-TE信令协议做出的组播扩展.在实验网络环境里完成了组播信令协议的实现并成功进行了组播树的建立、嫁接、剪枝和删除等操作.     

A hierarchical extension to RSVP-TE for fast lightpath setup in dynamic optical networks

A dynamic optical network with a fast resource allocation ability is proposed to satisfy the increasing requirement of the fast developing services. The lightpath setup delay of the traditional serial signaling distribution method used by RSVP-TE and CR-LDP increases linearly with increasing scale of the network. When the network size becomes too large, the signaling delay may cause problems to real-time services and fast recovery. So, we propose a combined hierarchical signaling distribution (CHSD) method for fast lightpath setup and an extended RSVP-TE to support a hierarchical signaling distribution process. The simulation and theoretical analysis show that the lightpath setup delay by CHSD is reduced from O(N), which is the delay of the traditional serial distribution method, to in the best condition. The delay is also related to the hierarchical structure of the network and when the scale of the routing areas (RA) takes a uniform distribution and the RA number equals to , a minimum distribution delay is achieved. Thereafter, we extend RSVP-TE to support this hierarchical distribution method. By the simulation result, the extension is proved to be feasible.     

ASON 中RSVP-TE可靠性和生存性机制研究

基于流量工程扩展的资源预留协议(RSVP-TE)作为自动交换光网络(ASON)中最重要的信令协议之一被广泛应用.RSVP-TE的可靠性和生存性机制直接影响到ASON的可靠性.文章具体分析了RSVP-TE的可靠性机制和支撑RSVP-TE生存性的软状态机制,阐述了影响生存性的两种基本故障类型--控制信道失效和平面节点失效,并深入研究了它们相应的恢复机制.     

新一代网络体系--智能光网络

首先介绍了传统的电信网络架构,指出其存在的问题并引出了新一代网络体系-智能光网络;然后说明了智能光网络的基本原理和它带来的巨大影响;最后描述了智能光网络的演进过程,并指出ASON的出现,将深刻地改变了光传输网的体系和功能。     

Distributed meta-scheduling in lambda grids by means of Ant Colony Optimization

Data transport infrastructures based on wavelength-routed optical networks are appealing to the grid community because they can provide a reconfigurable and high-bandwidth network service to emerging data-intensive grid applications. Traditionally, the control plane of those optical networks is independent from the management of other resources, such as computing systems, and it is commonly limited to fulfill immediate reservation demands of lightpaths. However, the lack of network integration to grid resources and the absence of advance reservation of bandwidth are critical aspects to the widespread adoption of optical networks in grid environments. Therefore, in this work, a distributed grid meta-scheduler based on an Ant Colony Optimization (ACO) algorithm is proposed, which is capable of co-allocating both optical networking and grid resources, under an integrated, extended and distributed control plane that supports advance reservations. The blocking probability and the delay for starting the processing of a request are evaluated for the proposed meta-scheduler under different resource co-allocation algorithms and different meta- and local scheduling policies, including the influence of the information aggregation across grid nodes. In addition, the benefits of the proposed approach are shown, such as grid and networking resource integration at the control plane, and capital expenditure reductions at the deployed optical network when compared to an immediate reservation scenario.     

Recovery from control plane failures in the RSVP-TE signaling protocol

The Resource Reservation Protocol for Traffic Engineering (RSVP-TE) must recover its state after a control plane failure so that the established connections in the data plane continue to be provided full services, are not disrupted by new connection setup requests, and survive any data plane failures. We outline the RSVP-TE Graceful Restart (GR) mechanism defined by the IETF. In this paper, we provide a comprehensive survey of the information that may be carried by RSVP-TE signaling messages when a connection is to be established and the state information that is stored in an RSVP-TE signaling module. We then propose an enhancement for RSVP-TE GR to alleviate the requirement of local recovery of the data plane state. Our proposal includes a two-step RSVP-TE state recovery, which uses a fast recovery to recover the RSVP-TE state in which labels were idle before a control plane failure and a detailed recovery to recover all of the RSVP-TE state. The fast RSVP-TE state recovery is realized as an extension to the RSVP-TE Hello mechanism, allowing a restarting node to process new connection setup requests as quickly as possible without interfering with existing connections. The detailed RSVP-TE state recovery generally follows RSVP-TE GR with minor modifications that can be performed in the background in parallel with normal RSVP-TE operations for connection setup and removal. Our performance evaluations show that our proposal shortens the waiting time for new connection setups being processed by a restarting node.     

基于RSVP-TE的温和重启机制的理论研究

目前,在高端路由器上的路由协议（比如ISIS、OSPF、BGP、LDP等）越来越多地采用Graceful Restart机制来实现“无中断转发、平稳协议重启”的功能.RSVP-TE作为实现网络核心区域流量工程的关键技术,也同样可以支持Graceful Restart机制,本文详细介绍了RSVP-TE Graceful Restart的原理和工作过程.     

ASON中光路快速创建的方法

光路的快速创建在自动交换光网络(ASON)中具有重要意义,它有利于快速地提供业务和故障的快速恢复。从信令角度介绍了GMPLS在RSVP和CR-LDP基础上所做的一些扩展,包括上游建议标签和标签集,双向光路的创建,快速通告机制,波段交换,遇阻塞返回及反馈机制,给出了使用这些扩展建议来快速创建光路的方法。