支持多通道传输的光子网格资源并行调度策略

为满足分布式业务对资源使用灵活性和网络高带宽性的要求,实现高性能光网络,对光子网格体系结构进行了研究,并提出支持多通道传输的光子网格资源并行调度策略. 利用可分负载均衡策略分割数据或执行大文件分片,结合多波长并行预留机制,在应用驱动下按需分配光路资源. 构建光子网格实验平台,以电力分布式潮流数据传输应用为例验证所提策略的有效性. 实验结果表明,在应用驱动下并行调度策略能提供灵活的光网络资源分配,有效提高分布式业务的传输性能及光网络资源利用效率.     

Grid-Controlled Lightpaths for High Performance Grid Applications

Grid applications call for high performance networking support. One attractive solution is to deploy Grids over optical networks. However, resource management in optical domains is traditionally very rigid and cannot successfully meet the requirements of Grid applications, such as flexible provisioning and configuration. In this paper, we present a customizable resource management solution for optical networks where users can create lightpaths on demand and manage their own network resources. Thanks to a Grid-centric system architecture, lightpath resources can be shared among users and easily integrated with data and computation Grids.     

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.     

Design of low‐power all‐optical networks under the constraint of four‐wave mixing

In this paper, we propose a static lightpath establishment method to design low‐power all‐optical networks under the constraint of four‐wave mixing (FWM). Since the FWM causes nonlinear interchannel crosstalk, it degrades the communication quality of optical signals. The FWM crosstalk effect becomes strong in a fiber as the number of passing optical signals increases. Therefore, we should reduce the number of optical signals passing through the same fiber from the perspective of the FWM. Meanwhile, in order to enhance the power efficiency of optical amplifiers, which are deployed at each optical fiber, it is preferred that multiple optical signals are transmitted in the same fiber. In order to decrease the power consumption while keeping high communication quality, the proposed method statically selects routes, wavelengths, and fibers for each traffic demand, considering the FWM crosstalk effect and the usage efficiency of the optical amplifiers. We show the performance of the proposed method through numerical experiments.     

网状WDM网络的抗毁设计

本文使用整数线性规划法对多光纤网状WDM网络进行抗毁设计,使用的保护策略为共享通道保护和共享链路保护,网络设计的优化目标是使全网铺设的光纤总长度最短。然后以类CERNET为例,求解出不同保护策略下网络需要的光纤总长度,并分析了它们各自的特点以及波长转换对目标函数值的影响。     

Algorithms for Dynamic Routing in All-Optical Networks

In this paper, we have studied a number of algorithms for routing in all-optical wavelength routed networks. We have considered situations where a lightpath is dynamically created in response to a request for communication and the WDM channels constituting the lightpath are reclaimed when the communication is over. We have looked at two schemes for dynamic wavelength allocation. In the first scheme we have assumed the existence of a central agent to maintain a database of existing lightpaths where the central agent attempts to generate a new lightpath in response to a request for communication. In the second scheme, we attempt to generate a new lightpath using a distributed algorithm. In the first scheme we have exploited the existence of multiple paths between any pair of nodes in a network in order to reduce the blocking probability. For the second scheme, we have proposed three distributed strategies to determine, if possible, a lightpath when there is a request for communication. Each of these strategies have their advantages and disadvantages in terms of the expected blocking probability and the set-up time. We have studied the performances of both the schemes using Monte Carlo simulation.     

Routing wavelength and time-slot reassignment algorithms for TDM based optical WDM networks

In this paper, we consider the problem of maximizing the time of first lightpath request rejection, T in the circuit-switched time division multiplexed (TDM) wavelength-routed (WR) optical WDM networks. TDM is incorporated into WDM, to increase the channel utilization when the carried traffic does not require the entire channel bandwidth. In TDM–WDM network, multiple sessions are multiplexed on each wavelength by assigning a sub-set of the TDM slots to each session. Thus, given a session request with a specified bandwidth, a lightpath has to be established by using the routing, wavelength and time-slot assignment (RWTA) algorithms. If the lightpath cannot be established, lightpath request rejection or call blocking occurs. As each lightpath is substantial revenue and long-lived, lightpath request rejection is highly unfavourable in the optical backbone networks. In this paper, we are proposing an intelligent routing, wavelength and time-slot reassignment algorithm for multi-rate traffic demands, where, when a call gets blocked, the already established calls in the network are rerouted, wavelength and time-slot reassigned so as to accommodate the blocked call. Since we are talking of slow arrivals and long holding times for the lightpaths, it is possible to do this reassignment while provisioning a new call. Simulation based analyses are used to study the performance of the proposed reassignment algorithm. The results show that the proposed reassignment algorithm can be used to maximize the time of first call blocking, thereby accommodating more calls in the network before upgrading the network capacity.     

CLEP——一种新的全光网络光路建立协议

本文提出了一种波长交换光网络中混合模式的光路建立协议CLEP,该协议充分利用现有基于正向预留的CR-LDP协议和基于反向预留的RSVP-TE协议各自的特点,通过使用混合模式的光路建立机制,使得信令协议在控制消息负载、实现复杂度、连接阻塞概率和连接建立时间等方面具有更好的性能.     

A Novel Distributed Protocol for Path Selection in Dynamic Wavelength-Routed WDM Networks

This paper solves the problem of path selection for WDM mesh networks with a special focus on the implementation in middle-sized networks, such as metropolitan-area networks (MANs). A novel routing and signaling protocol, called asynchronous criticality avoidance (ACA), is proposed to improve the network performance. With the ACA protocol, a specific set of wavelength channels are defined as critical links between a node pair according to dynamic link-state. Criticality information is defined as the critical links and the associated information, which is coordinated and disseminated by each source node to every other source node as an inter-arrival critical coordination. Routing and wavelength assignment is performed along with the criticality avoidance mechanism, in which path selection process is devised to take the criticality information into consideration. Simulation is conducted in 22- and 30-node networks to examine the proposed approach. The simulation results show that the ACA protocol significantly outperforms the fixed-path least-congested (FPLC) and adaptive dynamic routing (ADR) schemes under the fixed alternate routing architecture.     

Wavelength‐transparent IP‐over‐CWDM network with stackable ROADMs for best effort performance

Stackable reconfigurable optical add/drop multiplexers (S‐ROADMs) have been proposed for use in IP over coarse wavelength‐division multiplexing (CWDM) networks so as to provide capabilities of remote lightpath reconfiguration and manual ROADM reconfiguration under the best effort transmission specified by the service level agreement. The S‐ROADM can be constructed by connecting modules with different wavelengths required in the node. The experimental results clarify that the S‐ROADM can add/drop or pass through the wavelengths successfully, providing no limit to the passing‐through (PT) wavelengths, that is, ensuring the wavelength transparency in the network. The S‐ROADMs could remove congestions by adding a lightpath remotely within a recovery time with degraded SLA. The transmission break time was also within the recovery time when adding a module manually to the in‐service S‐ROADM to increase bandwidth to be provided to new users. As a result, the S‐ROADMs provide more flexible CWDM networks in terms of scalability and reconfigurability. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.