一种基于折回点重路由的折回机制在ASON中的应用

该文提出了ASON网络中一种基于折回点重路由的折回机制,当连接发生折回时,该机制通过折回点对连接进行重路由,从而省去了折回消息发送的过程。为了实现该机制,扩展了信令消息及处理流程。搭建了15个节点的试验平台,采用了RSVP-TE、OSPF-TE及LMP等协议来实现ASON网络的控制平面。试验数据显示该机制与传统的折回机制相比较,不但节省了信令通信网(SCN)的带宽,而且节省了连接的最终建立时间。     

解读ASON自动发现协议

ASON(自动交换光网络)与SDH或OTN网的最大差别在于引入了智能控制平面。通过呼叫控制、连接控制、路由和信令协议,控制传送平面的建立、保持和拆除各种连接,实现快速、有效的连接管理;同时,ASON还支持“智能”链路恢复功能。要实现上述目标,控制平面必须对传送层的网络拓扑了如指掌。邻居自动发现即是拓扑发现、提高网络构建和运营效率的有效方法。ITU-T在推出一系列描述ASON网络结构、分布式呼叫和连接管理、路由、GMPLSRSVP-TE信令等建议后,又对自动邻居发现的机制、消息格式等进行了规范,正式批准了G.7714.1(SDH和OTN网中的自动发现协议),向下一代光网络ASON的实现又跨出了坚实的一步。     

ASON中共享路径保护机制的实现方法

研究了自动交换光网络(ASON)中,保护资源可部分共享的共享路径保护机制(Shared Path Protection,SPP)如何实现的问题.设计了该机制在符合波长连续性限制条件的WDM光网络中的路由计算算法及在ASON上实现该机制的信令流程.在ASON实验平台上实现了该机制.     

新的ASON路由实现方案

提出了一种新的基于OSPF的ASON路由实现方案,扩展了波长链路状态公告和网络节点链路状态公告,用于在全网分发波长和网络拓扑信息。实现了拓扑的自动发现和路由信息的可靠分发,并提供了友好的RWA接口以便引入各种RWA算法和动态连接建立信令协议。通过仿真对本方案进行了验证,比较了若干RWA算法的性能,分析了两类路由信息更新触发策略和在全网分发波长信息的可行性。     

ASON路由协议OSPF—TE的分析与仿真

自动交换光网络（ASON）通过在传统光传送网络中引入路由协议、信令协议来实现网络的智能化。文章对ASON路由协议——基于流量工程开放最短路径优先协议（OSPF—TE）的基本概念和工作机制进行了分析研究，并仿真了OSPF-TE的一些网络性能，并得到一些有益的仿真结果。     

自动交换光网络中的信令协议和恢复分析

文章介绍了自动交换光网络(ASON)中的信令协议.信令协议主要完成标签交换路径(LSP)的建立、维护和释放.文章集中阐述了为支持ASON而对信令进行的扩展,包括扩展的消息和消息中所携带的信息,以及在ASON中建立一条LSP的过程.最后,着重对LSP建立和恢复过程的时间进行了详细的分析.     

基于拓扑预测与LLDP控制的天基网络路由方法

随着SDN的兴起,许多基于SDN的天基网络架构被提出,但这些架构没有考虑突发情况对网络拓扑的影响以及LLDP的合理使用。针对以上不足,提出基于拓扑预测与LLDP控制的天基网络路由方法。该方法采用基于SDN的网络架构,在正常情况下关闭LLDP协议,根据预测拓扑直接计算路径下发流表;在突发情况下开启LLDP,获取实时拓扑然后计算路径下发流表。为了验证TP-LC,搭建基于SDN交换机的仿真平台,能够同时模拟天基网络特性与SDN架构特性。仿真结果表明,TP-LC与Open SAN相比,降低了信令开销,减少了数据丢失。     

自动交换光网络的GMPLS实现及应用

介绍了自动交换光网络(ASON)与通用多协议标记交换(GMPLS)之间的关系,分析了GMPLS的层次结构模型,针对实际应用介绍了信令、路由和链路管理等协议,并在此基础上给出利用GMPLS实现ASON控制平面的一般方法和标记交换路径(LSP)创建过程,最后阐述了ASON的应用及存在的问题。     

一种基于ASON的新型动态恢复路径建链协议

讨论了动态波长路由光网络的恢复路径提供问题，在联合可变权重路由选择(JVWR)算法的基础上重点对恢复路径建立时延进行了分析，通过对恢复路径建立过程中的非物理资源相关因素的考虑，基于ASON控制平面的分布式信令协议提出了前向并行建链协议(FPLSP)。理论分析和仿真实验表明，该建链协议对于减少恢复路径链路建立时延具有明显的效果。     

ASON中信令协议RSVP_TE建立LSP的研究

文章对自动交换光网络（ASON）信令协议——基于流量工程扩展的资源预留协议（RSVP_TE）的主要内容及工作机制进行了分析研究,它主要是在ASON网络中动态地完成建立、保持和删除标签交换路径（LSP）。LSP的建立时间与信息传输时延、信息处理时延和节点配置时间有关。在RSVP_TE信令基础上提出一种新的标签分组方式来减少LSP建立时延。从理论和仿真上都验证了采用这种标签分组方式会改善LSP建立时延性能。     

基于PNNI的ASON路由协议

通用多协议标签交换(GMPLS )是将多协议标签交换 /流量工程(MPLS-TE )进行光网络扩展,并被广泛接受作为自动交换光网络(ASON )控制面协议的理想选择,然而标准化组织正讨论研究将专用网网间接口( PNNI )协议用于 ASON 控制面的潜力。文中主要通过对 PNNI 的路由分层概念、 PNNI 的路由信息分发机制和 PNNI 的路径选择机制的介绍,给出 PNNI 路由的几个扩展,以适合 ASON 的路由需求。     

分层路由-新一代智能光网络的路由技术

近几年数据业务正在持续快速地增长,为了满足日益增长的带宽需要和不断提高的服务质量要求,光网络正朝着智能化的方向不断发展.智能光网络,特别是自动交换光网络(ASON)的提出代表了光网络的发展方向,成为下一代光网络结构的研究焦点.为了提高网络的可扩展性和灵活性,满足ASON面向连接的网络特性,ASON网络采用了分层路由技术,通过拓扑抽象将ASON网络的路由结构层次化,利用聚合的路由信息简化选路过程.分层的路由结构使得运营商能够屏蔽网络的内部细节,提高网络的安全性,并且可以任意配置网络内部结构,使整个光网络具有高度的灵活性和可扩展性.本文深入分析了ASON网络的分层路由体系结构和分层路由对域间接口的功能要求,详细地介绍了适用于ASON分层路由的DDRP路由协议,并讨论了基于DDRP的ASON分层路由的组网实现方案.     

基于GMPLS协议的ASON试验平台

文章介绍了清华大学自主研发的基于通用多协议标签交换(GMPLS)协议的自动交换光网络(ASON)试验平台.试验平台由3个层面构成,分别为传送层面、控制层面和管理层面.传送层面由4个光交叉连接(OXC)和1个光上下路复用器(OADM)构成的传送网络组成;控制平面由多个协议模块构成,包括链路管理、路由和信令模块,这些协议的实现都是基于互联网工程任务小组(IETF)的GMPLS协议开发和实现的;管理平面完成配置管理和故障管理,包括网元管理以及软永久连接的触发等.试验平台支持动态可配置的网络拓扑、自动邻居发现、受限路由以及光层快速的保护和恢复功能.     

Load balance in hierarchical routing network

In this article, the problem of load balance in hierarchical routing network is studied. Since conventional shortest path first (SPF) algorithm over aggregated topology in hierarchical routing network may result in worse routing performance, a traffic sharing path selection algorithm and a variable weight scheme are put forward for hierarchical routing network, which can equilibrate the utilities of link resources and reduce the blocking probability of connections with the improvement on survivability. Simulations are conducted to evaluate proposed variable weight and traffics balance (VWTB) algorithm, which combines traffic sharing and variable weight. From the simulation results, it can be found that the proposed VWTB algorithm can balance the traffics and equilibrate the utilities of link resources significantly.     

Improving path duration in high mobility vehicular ad hoc networks

In this paper, we consider a high-speed highway mobility scenario, where the available knowledge about the network’s topology is used to improve the routing path duration. The improvement is mainly due to the use of a topology control algorithm, which increases the path duration by decreasing the probability of path breaks. For network regions having an enough density of vehicles, the packets are preferentially routed over the oldest links created by the vehicles moving in the same direction. For smaller values of vehicles’ density, the routing preferentially uses the most recent links created in both moving directions. This choice is shown to increase the routing path duration.The topology control scheme here proposed can be easily integrated in the existing routing protocols: we describe how to integrate it in the Optimized Link-State Routing Protocol (OLSR).¹ We compare the performance of our approach with other routing protocols for different values of vehicles’ density. The comparison includes end-to-end path delay, path availability and path length (in number of hops). Finally, we evaluate the path duration achieved with our approach, concluding that it exhibits a significant improvement over the most relevant topology and position-based routing protocols.     

An Inter-domain Routing and Signaling Scheme for Optical Mesh Networks

An inter-domain routing and signaling scheme based on the OBGP protocol for WDM networks with a mesh topology is proposed in the paper. For mesh networks with wavelength conversion, inter-domain routing and signaling are realized by introducing a new message based on an optimal path identifier (OPI) and by establishing the corresponding message-exchange procedures. Considering the wavelength continuity constraint, a strategy called improved destination wavelength assignment (IDWA) combined with the OPI-based message is presented to establish a lightpath dynamically. The scheme is verified on the NSFNET and the CERNET by simulation. Results show that the blocking performance of a non-wavelength-conversion network is even a little lower than that of a wavelength-conversion network.     

Experimenting with bandwidth-variable routing and signaling on a large-scale ASON test-bed

Bandwidth-variable (BV) optical networks have been proposed as a novel technology to provide spectrum-efficient transportation. In order to study the performance of the BV optical networks, we propose a BV extension to RSVP-TE signaling protocol and implement it with different routing schemes on our large-scale ASON test-bed. Results show that the adaptive routing (AR) combined with forward reservation RSVP-TE signaling (AR+RSVP-fBV) scheme has lower routing blocking probability; however, since its signaling blocking probability is higher than the fixed routing (FR) combined with backward reservation RSVP-TE signaling (FR+RSVP-bBV) scheme, it has no significant advantage in the overall blocking performance, especially in a highly dynamic network scenario. The introduction of spectrum conversion cannot improve the overall blocking performance significantly due to its higher signaling blocking probability, and worse yet, it increases setup delay.     

基于PCE的ASON路由技术研究

由因特网工程任务组(IETF)路径计算单元(PCE)工作组定义的基于PCE的多协议标签交换/通用多协议标签交换(MPLS/GMPLS)网络结构能有效解决多层网络中端到端的路径计算问题.文章从自动交换光网络(ASON)路由技术的发展趋势出发,根据有关PCE的RFC文档对PCE的体系结构、发现机制和策略进行了较为系统的说明,重点对PCE在ASON路由中的应用及PCE路径保护和恢复机制进行了阐述,表明PCE技术将成为ASON路由技术的首要选择.     

Toward path reliability by using adaptive multi-path routing mechanism for multimedia service in mobile Ad-hoc network

Traditional multi-path routing mechanisms aim to establish complete node or link disjoint paths.However,under some circumstances if multiple paths cannot be established based on the current network topology,the traditional multi-path routing mechanism will degenerate into single path routing mechanism,thus the advantages of multi-path routing cannot be exhibited.To enhance the end-to-end path reliability,an adaptive multi-path routing mechanism with path segment is proposed,in which multi-path can be establ...