多协议标记交换（MPLS）技术

从IP与ATM结合技术的演变入手，阐述了MPLS的基本原理，并重点介绍了LSP的建立过程。同时，对MPLS的控制协议进行了比较。     

多协议标签交换（MPLS）路由器的设计

MPLS技术结合了IP和ATM的优点而适应网络发展的需要,本文着重介绍MPLS路由器的设计以供同行在设计高端路由器时参考。     

MPLS的体系结构与组网技术

本介绍了目前网络界研究热点的宽带网络技术MPLS。重点阐述了MHLS的主要组件和核心技术。最后对ATM上的MPLS组网技术进行了介绍。     

MPLS的体系结构与组网技术

本文介绍了目前网络界研究热点的宽带网络技术MPLS(多协议标签交换)。重点阐述了MPLS的主要组件和核心技术。最后对ATM上的MPLS组网技术进行了介绍。     

IP的出路--多协议标签交换(MPLS)

作为下一代网络的来越重要的角色.介绍了MPLS的概念、组成,详细分析了其工作原理及其承载的各种应用,为打造支持未来3G业务的精品IP承载网提供了一些参考.     

多协议标记交换(MPLS)综述

在各种 IP和 ATM结合的方法中 ,多协议标记交换 (MPL S)是目前最有发展前途的。通过讨论标记的分配、分布和封装 ,以及标记站和数据流融合等问题 ,详细说明了 MPL S的基本模型及其工作原理 ,并在此基础上对使用 ATM技术后的多协议标记交换与传统 Internet进行了比较     

一种应用WR和OBS混合结构

密集波分复用（DWDM）技术的发展为光网络带来了新的应用前景,它是高带宽需求最好的解决方法之一.本文给出了光突发交换和波长路由两种技术的基本特征,并讨论了每个实现机制的优缺点,提出了融合这两种技术以克服使用单一方式的限制的新结构.     

Optical Switching Networks With Minimum Number of Limited-Range Wavelength Converters

We study the problem of determining the minimum number of limited-range wavelength converters needed to construct strictly, wide-sense, and rearrangeably nonblocking optical cross-connects for both unicast and multicast traffic patterns. We give the exact formula to compute this number for rearrangeably and wide-sense nonblocking cross-connects under both the unicast and multicast cases. We also give optimal cross-connect constructions with respect to the number of limited-range wavelength converters.     

Connection Establishment of Label Switched Paths in IP/MPLS over Optical Networks

We propose and investigate three connection admission control policies for the establishment of label switched paths (LSPs) in IP/MPLS over optical networks. We show that the policy of establishing LSPs first in the optical layer achieves a better blocking performance. We examine the effect of the number of add/drop ports of optical cross-connects (OXCs) on the LSP blocking performance. We show that there exists a lower bound for the number of add/drop ports of OXCs for the network to achieve almost the best LSP blocking performance.     

基于调频调幅方式的光标记网络的传输性能

数值模拟了IP-over-WDM光网络中基于频移键控/幅移键控(FSK/ASK)正交调制的光标记信号/净荷的传输性能.结果表明,ASK净荷的传输同时受到调制器消光比、接收光功率及光纤色散的影响;FSK光标记信号则主要受到调制器消光比和接收光功率的影响,几乎不受光纤色散因素的影响.     

Group-Scheduling for Multi-Service Optical Burst Switching (OBS) Networks

We propose a new burst scheduling mechanism for Optical Burst-Switched (OBS) networks. The new approach is made possible by gathering data bursts into groups and performing the scheduling decision for each group collectively. In OBS group-scheduling, bursts will not be considered for scheduling until a pre-defined time period elapses, during which the group of burst header packets would be gathered. By transforming a set of data bursts into a set of corresponding time intervals, the problem of scheduling these bursts is transformed into a combinatorial optimization problem. Graph algorithms are applied to obtain the maximum number of non-overlapping bursts. The proposed OBS group-scheduling scheme is shown to improve the performance of OBS networks over existing scheduling schemes in terms of burst loss probability and channel utilization. With an extension through a sequential optimization, using a Branch-and-Bound technique, the proposed scheme can support multiple classes of service. It is shown that the new scheduling approach has several desired characteristics including fairness and service differentiability among classes in terms of burst loss probability and channel utilization.     

Sparse Regeneration in Translucent Wavelength-Routed Optical Networks: Architecture,Network Design and Wavelength Routing

In this paper we study an alternate network architecture, called translucent network, to the fully transparent and fully opaque network architectures. In a translucent wavelength-routed optical network, a technique called sparse regeneration is used to overcome the severe lightpath blocking due to signal quality degradation and wavelength contention in a fully transparent network while using much less regenerators than in a fully opaque network. In this paper, we present a node model and a network model that perform sparse regeneration. We address the problem of translucent network design by proposing several regenerator placement algorithms based on different knowledge of future network traffic patterns. We also address the problem of wavelength routing under sparse regeneration by incorporating two regenerator allocation strategies with heuristic wavelength routing algorithms. We compare the performance of different regenerator placement algorithms and wavelength routing schemes through simulation experiments. The benefit of sparse regeneration is quantitatively measured under different network settings.This work was supported by NSF grants (ANI-0074121 and EPS-0091900).Portions of this work have appeared in the Proceedings of the OSA Optical Fiber Communications (OFC 1999) Conference [6] and the Proceedings of the IEEE Global Telecommunications (GLOBECOM 2001) Conference [12].     

基于正交调制的IP-over-WDM光标记交换网络及其传输性能的研究

详细阐述了基于正交调制格式的IP-over-WDM光标记交换网络的网络体系结构,给出了边缘路由器的结构图与核心路由器的实现方法,数值模拟了IP-over-WDM光网络中基于频移键控/幅移键控正交调制的光标记信号/净荷的传输性能,最后给出了基于正交调制格式的IP-over-WDM光标记传输实验,实验结果表明了所述方案的可行性。     

Dynamic Routing and Wavelength Assignment Using Cost Based Heuristics in WDM Optical Networks

Dynamic routing and wavelength assignment problem in optical networks is a two-step problem that is influenced by the choice of a successful optimal path selection and wavelength assignment. Proper selection techniques reduce the number of wavelengths required in the network and thereby improves traffic grooming. Heuristic algorithms and integer linear programming models help in selection of route and wavelength separately. Hence, the computation time is large which makes the system slow. A cost function is computed which uses independent parameters in the network for the selection of route and wavelength for a call. The heuristic reduces computation time by combining the search of route and wavelength to be assigned. In addition, the network performance is analyzed with and without alternate routing along with proposed heuristics. The selection of proper route and wavelength finding technique is very essential since it improves the grooming factor of the network thereby allowing more traffic support by the network. Our objective is to investigate and propose a cost based heuristics for dynamic traffic routing and wavelength Assignment in WDM optical networks. For this we plan to develop cost functions and heuristics to compute the route and wavelength assignment strategy. Here, our objective is to reduce the computation time for selection of route and wavelength assignment strategy by weighted cost function. The function has to include network parameters for its processing. Our work provides an overview about DRWA by applying cost based heuristics in WDM networks. This paper explains the proposed cost function and its applications in line with selection of independent parameters. The details of other functions like cost function formulation, hop-based route assignment, available wavelength based route assignment, mathematical analysis of proposed cost function are also explained. Results and discussions based on the findings are presented.

     

光交换的时间及空间结构分析

拓扑学上的光网络由边(光传输)和节点(光交换)组成。从业务属性出发,基于连接和无连接方式,分析了光交换的时间结构,包括光分组和光突发的时间结构,以及不同动态性的光电路交换的时长及其度量标准,结合实验结果分析了最短光电路交换的时长极限。从多端口和大容量的要求出发,重点讨论了基于微电子机械系统(MEMS)开关、波长选择开关(WSS)和阵列波导光栅(AWG)的三种光交换结构。分析了光交换结构的扩展方法,并讨论了光交换的几个具有挑战性的问题,包括缓存和能耗问题。通过分析,希望从时间和空间两个维度更清晰地认识光交换的本质及其与电交换的异同。     

High-Speed Optical Time-Division Multiple-Access (OTDMA) Networks Using Optical Signal Processing

In this paper, we design high-speed optical fiber networks based on the time-division multiple-access (TDMA) technique. To achieve an ultrahigh throughput, optical signal processing should be used in the network. We present a feasible scheme to implement optical TDMA networks, with the emphasis on optical clock distribution, synchronization, and optical time demultiplexing. Since the proposed network uses two wavelengths to carry optical TDMA and clock signals respectively, at each TDMA receiver slot synchronization is feasibly achieved by using simple optical delay lines to process the separated optical clock and TDMA signals. This in turn allows us to build a large-scale distribution network which is attractive for future HDTV broadcasting applications. Using the proposed scheme also allows to implement a high-capacity broadcast and select optical TDMA network for real-time data communications.     

Comparative Account of Bandwidth Efficiency in Optical Burst Switching and Optical Circuit Switching Networks

The performance of Optical Burst Switched (OBS) networks is compared to that of Optical Circuit Switched (OCS) networks in terms of bandwidth efficiency. Two traffic flow models are employed to investigate the effects of traffic grooming, packetization, buffering and burst assembly on bandwidth efficiency and utilization. Traffic is represented by fluid-flow continuous bit streams in the first model and by packet-based discrete flows in the second model. It is shown that the parameters of traffic characteristics and burst assembly have significant impact on the relative bandwidth savings of OBS. The bandwidth efficiency of OBS compared to OCS should not be taken for granted and has to be examined carefully on a case by case basis.     

基于多重光正交码光标签的光分组交换系统实验研究

采用多个光正交码串行排列组成的多重光正交码(MOOC)标签格式,提高了可用标签的数目;构建了基于MOOC标签的光分组交换系统(OPS),对该系统中的各项关键技术,包括光分组信号产生单元、光标签处理单元、交换控制单元,光交换矩阵等进行了分析和研究;完成了光分组交换系统演示实验,并对实验结果进行了讨论.     

GMPLS技术及其路由算法

通用多协议标签交换（ GMPLS）是由多协议标签交换（MPLS）发展而来,它是MPLS向光层扩展的必然产物.GMPLS将时隙、波长和光纤端口作为标签用子数据转发,通过采用扩展的信令、路由协议和新增的链路管理机制以适应对智能光网络进行动态控制和传送信令的要求,动态提供网络资源并增加网络的存活性.本文着重比较了GMPLS与MPLS,说明其如何改进MPLS,并提供了GMPLS在光控制平面的应用解决方案.最后,谨慎分析了GMPLS的前景及其需要解决的问题