长途网选路方式的选择与发展探讨

结合当前长途网选路方式，对固定有级选路、固定无级选路、动态无级选路3种选路方式进行了简单介绍，并对它们的性能进行比较，提出动态无级选路是中国电信长途网的最终选路方式。     

固定无级选路的试点情况简介

１固定无级选路的试点背景１.１路由选择方式目前全网使用固定有级选路,其路由选择顺序为:首选直达路由,次选迂回路由,终选基干路由。这种可选择的路由选择顺序在任何时候、任何情况下都是固定不变的,而不考虑这两段路由上的实际话务情况能否承受迂回过来的话务。该路由选...     

我国通讯网结构演变策略

一、国外通讯网演变过程及经验 电信网的结构形式分为多级网和无级网。多级网是接大区、省区、地区和县的次序逐级分区和按直达路由—迂回路由。基于路由顺序选路的原则,建立起来的电路交换分级网。无级网是指网中所有节点均被视为同级,无上、下级之分。 1、美国 美国的长途电信网在30年代时为3级结构,50年代演变为5级结构,80年代中期开始向无级制发展。20年代末,贝尔系统提出了第一套长话交换总体规划。据此规划,30年代     

无级动态网技术及其在中国的前景

一、概述 无级动态网技术是为适应电信网中普遍存在的话务量忙时不一致性而出现的一种新技术,是电话交换网相对于传统的分级结构和固定选路而言的另一种存在形式,其网路结构和路由选择技术与传统的电话交换网都有本质的区别。首先,传统的电话交换网中的各交换节点是“分级”的,网中路由选择是受交换中心级别限制的;而在动态无级网中,所有     

关于在长途网上引入固定无级选路机制的探讨

在全网实现了交换程控化和传输数字化的基础上，对经过长途网路的优化调整，目前我国的长途电话网已从传统的四级网过渡到两级网。但是，相应的选路技术还未更新本文从引入固定无级选路的必要性、重要性以及对固定无级选路的优缺点和业务保护需求的原理和方法做了简要论述。     

一种自选路由ATM容错交换网络

本文提出一种自选路由ＡＴＭ容错交换网络结构，网络通过在基准网的级间增加交换单元来增加输入到输出间的通路，进而达到容错的目的，它具有选路简单，可提高交换网络性能的优点，与同等硬件量的其它容错方案比较，它可容纳更多的网络内部故障，且随着网络规模的增大，效果更明显。     

基于深度增强学习的软件定义网络路由优化机制

为优化软件定义网络(SDN)的路由选路,该文将深度增强学习原理引入到软件定义网络的选路过程,提出一种基于深度增强学习的路由优化选路机制,用以削减网络运行时延、提高吞吐量等网络性能,实现连续时间上的黑盒优化,减少网络运维成本。此外,该文通过实验对所提出的路由优化机制进行评估,实验结果表明,路由优化机制具有良好的收敛性与有效性,较传统路由协议可提供更优的路由方案与实现更稳定的性能。     

长途网固定无级选路的技术

1 我国长途网的现状我国当前的长途两级网仍沿用以前四级网固定分级的选路方式,呼叫在高平面网状网的任意一个路由上都不允许溢出。这样的规定主要基于两方面的考虑,一是对于任意一个方向的呼叫,网路都能提供固定的最终路由,避免了网路在异常情况下的不稳定;二是由于有了固定的最终路由,而避免了呼叫在网路中选路时出现死循环。这样的选路方式在以往的网路组织中起到了应有的作用,也与当时的技术水平相适应。然而,由于话务量的增大和技术的进步,这种选路方式就显示出固有的缺陷。众所周知,任何一个网络都是按预测的话务量、一定的服务等…     

波分复用光传送网中备用选路下的选路和波长分配算法

本文研究了动态业务下,波分复用光传送网的选路和波长分配问题,提出了一种基于备用选路的选路和波长分配算法.与文献中已有的利用全网信息的备用选路的算法相比,该算法能更加精确地描述建立光路对全网的影响,选择对网络状态影响最小的路由-波长对来建立光路,促进网络资源的有效利用.计算机仿真表明,不论在规则的格型环网还是非规则的网络中,在阻塞率性能方面,在大多数情况下该算法优于文献中已有的备用选路算法;同时它也能改善公平性.     

固定无级选路的试点简析

固定无级选路是现代电信网路体制和网路管理的发展方向，为此电信总局安排1999年9月10日晚在南京H1进行固定无级选路试点，以使固定无级选路尽快在全网正式推广。文中对固定无级选路进行了详细的介绍，并对试点的效果进行评价，最后提出试点中存在的问题。     

The multi-copy diversity for routing in sparse vehicular ad hoc networks

The need for routing based on store-and-carry forwarding has been motivated in sparse vehicular ad hoc networks (VANETs), since the traditional end-to-end unicast routing is infeasible due to the network disconnection problem. In store-and-carry based routing, the end-to-end message delivery delay is dominated by the store-and-carry procedure rather than the wireless transmission. Therefore, the end-to-end delay in such sparse VANETs can be further reduced by replicating multiple copies of the message to other nodes when possible, i.e., multi-copy routing, to increase the chance of finally finding the destination, which we call this gain as multi-copy diversity. In this paper, we present an analytic framework to evaluate the performance of routing by assessing the multi-copy diversity gain in sparse VANETs. By using this model, we first derive an upper and lower-bound of end-to-end routing delay in sparse VANETs. Our analytic results show that a high level of multi-copy diversity gain is achieved when the network is partially connected, which is in contrast to the conventional expectation that multi-copy routing performs better in severely disconnected networks. Second, we propose a new adaptive multi-copy VANET routing scheme called AMR by exploiting these analytic results. AMR adapts to the local network connectivity and increases the level of multi-copy diversity at significantly reduced routing overhead compared to the well known epidemic routing. We validate the accuracy of our analytic model and the performance of AMR via simulation studies.     

An approximate analysis of the performance of deflection routing inregular networks

Regular two-dimensional architectures are being considered as alternatives to the linear topology metropolitan area networks (MANs) that are popular today. Deflection routing is an adaptive routing strategy that performs well on such architectures. A general analytic model has been developed to study the performance of buffered deflection routing in regular networks. The Manhattan street network, the ShuffleNet, and the shuffle exchange network have been studied as candidate two-connected networks with different topological characteristics. The results show that deflection routing performs well on both the Manhattan street network and the ShuffleNet, even under heavy loads, while on the shuffle exchange network it does not perform as well. The introduction of just a few buffers provides significant improvement in the delay-throughput performance over unbuffered deflection routing, especially in networks with large propagation delays. The analytic results are found to match the simulations very closely in most cases     

Network dimensioning and performance of multiservice, multirateloss networks with dynamic routing

We address a multiservice, multirate loss network environment with dynamic routing. In this setting, we consider multiple traffic load periods (multihour) during the day, and by observing network dynamics, we present a network dimensioning model that consists of two steps: a bandwidth estimation step, followed by a multicommodity flow model for multiple services and traffic loads. For network operations, we discuss a probabilistic admission control policy and three multiservice routing schemes. We have used a ten-node network with multiple asymmetric traffic data sets (partially extracted from an actual network) for our study. It was found that the capacity obtained using the analytic network dimensioning model provides a good estimate of network capacity required for meeting the grade-of-service goal for each service type in each traffic load period; this observation is based on a simulated network environment that uses the proposed admission control and the dynamic routing schemes. Our observation suggests that it may not be not necessary for the dimensioning model to explicitly incorporate an admission control policy, but admission control is needed for network operation to provide desirable grade-of-service     

Dynamic Routing and Flow Control

This is an expanded version of an earlier report, adding, new results. The first part introduces a simple analytic model showing that dynamic routing may increase network throughput or lower delay when trunks are moderately loaded, but will reduce throughput or increase delay at heavy trunk loads. The second part of the paper presents simulation results characterizing: 1) the operation of a network "protected" by end-to-end flow control, 2) the operation of an "unprotected" network, 3) the transition between these two modes, 4) the effect of changing the update interval for the routing algorithms, 5) the effect of slow local loops, and 6) the effect of increasing the number of alternate paths available for dynamic routing. Overall, the results show that dynamic routing improves network performance only over a small parameter range, and should dynamic routing be used at all, it must be implemented with great care.     

An Ad Hoc Routing Protocol with Multiple Backup Routes

Numerous routing protocols have recently been developed for ad hoc mobile networks. Routing protocols to date can be categorized as either ‘table-driven’ or ‘on-demand’. Many of the proposed routing protocols take the on-demand approach because this does not require keeping lots of routing information. However, these kinds of protocols are not able to react fast enough to maintain routing. In this paper, we propose a new protocol to improve existing on-demand routing protocols by constructing multiple backup routes; when the network topology changed, the proposed protocol could transmit data packets dynamically through backup routes. We then developed an analytic model to estimate the reconnection probability of the proposed algorithm. We also examined the performance by simulating the protocol using ns2. The experimental results showed that the protocol had fewer control packages, lower routing packet overhead, and a higher receiving ratio than others.     

应用二人零和对策理论的路由算法

本文讨论了在通信网的路由算法中应用二人零和对策理论的问题,提出了对策算法(GA)。GA以使网络平均分组时延最小为优化目标,给出了排队迟延和传播迟延间的解析结果。文中推导了有关GA的定理。业已证明,GA不仅能用作孤立路由算法,也可以用作分布路由算法。 借助于一个简单的网络模型,本文介绍了GA的使用例子,并将GA与最短路算法及热土豆算法的性能作了比较。     

Iterative approach to optimizing convergence routing priorities

This paper shows how to optimize the routing decisions in a nondeterministic routing algorithm called convergence routing in which routes may change depending on the traffic conditions. The routing algorithm guarantees a loss-free delivery of data packets from bursty sources, and a deterministic bound on the route length in arbitrary topology networks. The routing decisions are based on assigning routing priorities to the links such that a packet is forwarded to the highest priority link which is not blocked. Routing priorities are assigned using a local-greedy metric which minimizes the distance (number of hops) to the destination. This work shows that routing decisions using a local-greedy metric are not optimal, and the performance of the algorithm can be improved substantially by using new measures. Thus, various look-ahead metrics which take into account the potential gain on the other switching nodes toward the destination of a packet are suggested. The contributions of this work are: (1) a new analytical model to capture the behavior of a switching node; (2) an iterative optimization technique to set routing priorities according to various look-ahead measures; and (3) heuristics to ensure the stability of the routing priorities. The optimization objective is to maximize the throughput by minimizing the maximum total flow carried on a link in the network under static traffic model. The performance is studied computationally on various networks and traffic matrices. It is shown that up to a 50% performance increase can be obtained by optimizing the routing priorities     

组播路由选择的流体神经网络电路模型

提出了一种计算通信网络组播路由选择的流体神经网络模型,该模型充分利用网络的全局拓扑信息,将组播路由选择问题影射为一个电路求解问题,可在电路时间常数内给出组播的最佳路由。理论和仿真计算结果证明了该模型的可行性。     

Sharp approximate models of deflection routing in mesh networks

Deflection routing is a simple, decentralized, and adaptive method for routing data packets in communication networks. The focus of this work is on deflection routing in the Manhattan street network (a two-dimensional directed mesh), although the analytic approach should apply to any regular network. Two approximate performance models that give sharp estimates of the steady-state throughput and the average packet delay for packets admitted to the network are presented. The results of extensive simulation experiments are reported, which corroborate the models' predictions. The results show that deflection routing is very effective. Two measures of the merit of a network for deflection routing are its diameter and its deflection index. Networks are presented whose diameter and deflection index are near the optimal values     

Saturation routing network limits

Saturation routing means a flooding of a network with messages which search for a particular subscriber's number without regard to where that subscriber is located in the network. Saturation routing, often thought of as inappropriate in a communication network, can be a useful routing scheme with the use of state-of-the-art design. In this paper, consideration will be spent on the kinds of networks in which saturation routing is applicable, and how it compares with other routing systems. The functional designs of saturation routing will be combined with the appropriate variables to create a mathematical model for performing of saturation routing in a network. The following are some of the variables: i) processor rate; ii) transmission data rate; iii) hierarchy; iv) queuing delays; v) traffic; vi) message size. The paper will be concluded with an example of a realistic network using saturation routing.