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1.
Providing grooming capability to optical crossconnects (OXCs) in wavelength division multiplexing (WDM) networks can allow
an effective use of the network bandwidth, however, it increases the node cost that operators must sustain when compared to
a non-grooming network. Therefore, operators might consider using sparse grooming instead of full grooming networks. In this
article we consider sparse groomed optical networks. Our contribution is 2-fold. First, we address the grooming placement
problem that seeks for a set of grooming nodes in the network that leads to the highest overall throughput. This problem is
separated into two sub-problems: (i) selection of nodes having grooming capability; (ii) maximization of network throughput
assuming the grooming nodes found by the previous step. These two sub-problems are mathematically formulated for different
OXC placing strategies considering a static traffic scenario. In the second part, we design a practical heuristic grooming
algorithm suitable for dynamic traffic scenarios. The benefit of using sparse grooming nodes, when compared with a non-grooming
scenario, is evaluated in terms of throughput and optical port utilization. Our analysis differs of previous ones since it
considers grooming at a granularity coarser than the traffic granularity, which is an important aspect since network cost
improvement can be obtained at the expense of irrelevant performance impairments. Results show that the insertion of coarse
granularity OXCs can be a viable solution for network throughput increase since this can be done at the expense of relatively
few or no extra optical ports.
相似文献
M. C. R. MedeirosEmail: |
2.
We consider the problem of traffic grooming in WDM ring networks. Traffic grooming is a variant of the well-known logical topology design problem, and is concerned with the development of techniques for combining low speed traffic components onto high speed channels in order to minimize network cost. Previous studies have focused on aggregate representations of the network cost. In this work, we consider a Min-Max objective, in which it is desirable to minimize the cost at the node where this cost is maximum. Such an objective is of high practical value when dimensioning a network for unknown future traffic demands and/or for dynamic traffic scenarios. We present new theoretical results which demonstrate that traffic grooming with the Min-Max objective is NP-complete even when wavelength assignment is not an issue. We also present new polynomial-time traffic grooming algorithms for minimizing the maximum electronic port cost in both unidirectional and bidirectional rings. We evaluate our algorithms through experiments with a wide range of problem instances, by varying the network size, number of wavelengths, traffic load, and traffic pattern. Our results indicate that our algorithms produce solutions which are always close to the optimal and/or the lower bound, and which scale well to large network sizes, large number of wavelengths, and high loads. We also demonstrate that, despite the focus on minimizing the maximum cost, our algorithms also perform well in terms of the aggregate electronic port cost over all ring nodes. 相似文献
3.
The cost of an optical network in wavelength division multiplexing (WDM) networks can be reduced using optical reconfigurable
optical add/drop multiplexers (ROADMs), which allow traffic to pass through without the need for an expensive optical-electro-optical
(O-E-O) conversion. Waveband switching (WBS) is another technique to reduce the network cost by grouping consecutive wavelengths
and switching them together using a single port per waveband. WBS has attracted the attention of researchers for its efficiency
in reducing switching complexity and therefore cost in WDM optical networks. In this paper, we consider the problem of switching
wavelengths as non-overlapping uniform wavebands, per link, for mesh networks using the minimum number of wavebands. Given
a fixed band size b
s
, we give integer linear programming formulations and present a heuristic solution to minimize the number of ROADMs (number
of wavebands) in mesh networks that support a given traffic pattern. We show that the number of ROADMs (or number of ports
in band-switching cross-connects) can be reduced significantly in mesh networks with WBS compared to wavelength switching
using either the ILP or the heuristic algorithm. We also examine the performance of our band assignment algorithms under dynamic
traffic. 相似文献
4.
Girish V. Chowdhary A. Mahendra Varman C. Siva Ram Murthy 《Optical Switching and Networking》2006,3(2):89-103
In this paper, we address the problem of survivable multicast traffic grooming in WDM bidirectional ring networks. The rapid growth of multicast applications such as video conferencing, distance learning, and online auction, has initiated the need for cost-effective solutions to realize multicasting in WDM optical networks. Many of these applications, being time critical and delay sensitive, demand robust and fault-tolerant means of data communication. The end user traffic demands in metro environment are in fractional bandwidth as compared to the wavelength channel capacity. Providing survivability at connection level is resource intensive. Hence cost-effective solutions that require minimum resources for realizing survivable multicasting are in great demand. In order to realize multicast traffic grooming in bidirectional ring networks, we propose a node architecture based on Bidirectional Add Drop Multiplexers (BADM) to support bidirectional add/drop functionality along with traffic duplication at each node. We also propose two traffic grooming algorithms, namely Survivable Grooming with Maximum Overlap of Sessions (SGMOS) and Survivable Grooming with Rerouting of Sessions (SGRS). Extensive simulation studies reveal that the proposed algorithms consume minimum resources measured in terms of BADM grooming ports, backup cost, and wavelengths. 相似文献
5.
As the number of wavelengths in a single optical fiber increases, so does the number of ports needed for wavelength switching
in optical cross-connects (OXCs), which may significantly increase the cost and difficulty associated with controlling large
OXCs. Waveband switching (WBS) treats several wavelengths as a bundle that is switched through a single port if they share
the same switch route, so that the number of ports needed can be reduced. On the other hand, light-trails in wavelength division
multiplexing (WDM) optical networks allow intermediate nodes on established optical paths to access the data paths whereas
light-paths only allow two end nodes to access the data paths. Therefore, light-trails offer significantly better flexibility
for service provisioning and traffic grooming. In this article, we study service provisioning using light-trails in WDM optical
networks with the WBS capability under a static traffic model. For comparison, integer linear programs are formulated for
establishing light-trails with and without WBS. Numerical studies show that in certain cases, service provisioning with WBS
in light-trail networks can reduce the number of ports needed while providing a more flexible sub-wavelength service provisioning
capability. However, contrary to intuition, in most cases applying the WBS technique requires more ports in OXCs in light-trail
networks. This study provides insights into the network design problem that applies the WBS technology to light-trail based
optical networks. 相似文献
6.
7.
The bandwidth of a wavelength channel in WDM optical networks is very high compared to the user’s requirements for various
applications. Therefore, there is a scope for better utilization of channel bandwidth by traffic grooming, in which several
user’s channels are multiplexed for transmission over a single channel. Several research works have been reported on traffic
grooming routing and wavelength assignment (GRWA) for static and dynamic traffic pattern under centralized environment. Distributed
dynamic grooming routing and wavelength assignment (DDGRWA) is a new and quite unexplored area in WDM optical mesh networks.
This article introduces the concept of distributed traffic grooming in WDM mesh networks which also includes virtual topology
construction, reconfiguration, routing and wavelength assignment in the distributed environment assuming incoming traffic
to be dynamic in nature. We have also presented simulation results of our algorithm on dynamically generated traffic under
various network topologies. 相似文献
8.
Hongyue Zhu Hui Zang Keyao Zhu Mukherjee B. 《Networking, IEEE/ACM Transactions on》2003,11(2):285-299
As the operation of our fiber-optic backbone networks migrates from interconnected SONET rings to arbitrary mesh topology, traffic grooming on wavelength-division multiplexing (WDM) mesh networks becomes an extremely important research problem. To address this problem, we propose a new generic graph model for traffic grooming in heterogeneous WDM mesh networks. The novelty of our model is that, by only manipulating the edges of the auxiliary graph created by our model and the weights of these edges, our model can achieve various objectives using different grooming policies, while taking into account various constraints such as transceivers, wavelengths, wavelength-conversion capabilities, and grooming capabilities. Based on the auxiliary graph, we develop an integrated traffic-grooming algorithm (IGABAG) and an integrated grooming procedure (INGPROC) which jointly solve several traffic-grooming subproblems by simply applying the shortest-path computation method. Different grooming policies can be represented by different weight-assignment functions, and the performance of these grooming policies are compared under both nonblocking scenario and blocking scenario. The IGABAG can be applied to both static and dynamic traffic grooming. In static grooming, the traffic-selection scheme is key to achieving good network performance. We propose several traffic-selection schemes based on this model and we evaluate their performance for different network topologies. 相似文献
9.
In this article, we consider traffic grooming and integrated routing in IP over WDM networks. The challenges of this problem
come from jointly considering traffic grooming, IP routing, and lightpath routing and wavelength assignment (RWA). Due to
the high bandwidth of optical fiber, there exists a mismatch between the capacity needed by an IP flow and that provided by
a single lightpath. Traffic grooming is therefore used to increase the network utilization by aggregating multiple IP flows
in a single lightpath. However, traffic grooming incurs additional delays that might violate Quality-of-Service (QoS) requirements
of IP users. In this work, the tradeoff between traffic grooming and IP QoS routing is well-formulated as a mixed integer
and linear optimization problem, in which the revenue from successfully provisioning IP paths is to be maximized. Problem
constraints include IP QoS, routing, optical RWA, and the WDM network capacity. We propose a novel Lagrangean relaxation (LGR)
algorithm to perform constraint relaxation and derive a set of subproblems. The Lagrangean multipliers are used in the proposed
algorithm to obtain a solution in consideration of grooming advantage and resource constraints simultaneously. Through numerical
experiments and comparisons between the proposed algorithm and a two-phase approach, LGR outperforms the two-phase approach
under all experimental cases. In particular, the improvement ratio becomes even more significant when the ratio of IP flow
to the wavelength capacity is smaller. 相似文献
10.
Traffic grooming in an optical WDM mesh network 总被引:7,自引:0,他引:7
In wavelength-division multiplexing (WDM) optical networks, the bandwidth request of a traffic stream can be much lower than the capacity of a lightpath. Efficiently grooming low-speed connections onto high-capacity lightpaths will improve the network throughput and reduce the network cost. In WDM/SONET ring networks, it has been shown in the optical network literature that by carefully grooming the low-speed connection and using wavelength-division multiplexer (OADM) to perform the optical bypass at intermediate nodes, electronic ADMs can be saved and network cost will be reduced. In this study, we investigate the traffic-grooming problem in a WDM-based optical mesh topology network. Our objective is to improve the network throughput. We study the node architecture for a WDM mesh network with traffic-grooming capability. A mathematical formulation of the traffic-grooming problem is presented in this study and several fast heuristics are also proposed and evaluated 相似文献
11.
12.
This paper considers the on-line traffic grooming problem in WDM–TDM switched optical mesh networks without wavelength conversion
capability. In such a network, provisioning of connection requests with fractional wavelength capacity requirements is achieved
by dividing a wavelength into multiple time slots and multiplexing traffic on the wavelength. In this paper, we present an
on-line traffic grooming algorithm for the concerned problem. The objective is to efficiently route connection requests with
fractional wavelength capacity requirements onto high-capacity wavelengths and balance the load on the links in the network
at the same time. To do so, we propose a cost function, which not only encourages grooming new connection requests onto the
wavelengths that are being used by existing traffic, but also performs load balancing by intelligently increasing the cost
of using wavelengths on links. The performance results obtained by experiments on a representative sized mesh network show
that the proposed algorithm outperforms the other existing algorithms. 相似文献
13.
Advances in wavelength-division multiplexing technology have made it possible to design point-to-point transmission systems with unprecedented per-wavelength high capacity. This capacity may be exploited to design optical networks, in which end nodes are interconnected by circuits consisting of wavelengths. Contrary to early expectations, however, most of today's end-to-end applications require only sub-wavelength bandwidth. This bandwidth mismatch makes wavelength circuits inefficient in many cases, unless multiple traffic flows are time multiplexed together on the same wavelength. This practice is often referred to as traffic grooming. In this survey the authors address the issue of achieving efficient traffic grooming in static WDM networks. A great deal of discussion is devoted to the problem of determining which network solution is the most cost effective, taking into account the network topology, volume of traffic, possible optical impairments at high transmission rates, and cost ratio between electronic and optical components. 相似文献
14.
光网络中基于组播树的静态业务疏导算法 总被引:2,自引:1,他引:1
为了减少波分复用(WDM)网络中波长资源消耗,将组播路由算法的思想运用于静态业务疏导的计算,通过建立业务疏导树来实现静态业务疏导.为了减少疏导树的数量,从而减少网络中波长资源的消耗,将节点间的业务请求分组归并,利用装包算法使业务分组的数量最少,并通过构建最小生成树实现传输路径共享.仿真结果表明,本文的算法可以有效地减少... 相似文献
15.
Traffic grooming in WDM networks 总被引:22,自引:0,他引:22
The emergence of wavelength-division multiplexing technology has led to a tremendous increase In the available transmission capacity in wide area networks. Consequently, these networks may no longer be limited by the transmission bandwidth, but rather by the processing capability of electronic switches, routers, and multiplexers in the network. This realization has led to a new wave of research aimed at overcoming the electronic bottleneck by providing optical bypass at the WDM layer. Traffic grooming can be used as a bypass mechanism by which low-rate circuits are assigned to wavelengths in order to minimize the amount of electronic multiplexing equipment. This topic has received a significant amount of attention in both the research and commercial arenas. We give an overview of the traffic grooming problem and survey some representative work in this area. While most work has focused on grooming in SONET rings, grooming traffic in general mesh networks is an important emerging problem 相似文献
16.
Chunsheng Xin Chunming Qiao Sudhir Dixit 《Selected Areas in Communications, IEEE Journal on》2004,22(9):1658-1669
Traffic grooming is an important task in interworking between the wavelength-division multiplexing (WDM) optical network that supplies "pipes" at the wavelength granularity, and the attached client networks that usually require connections of subwavelength granularity. The focus of this paper is to conduct performance analysis of grooming dynamic client traffic in WDM optical networks with a mesh topology. This paper first briefly introduces the traffic grooming problem in WDM optical networks and the issues related to performance analysis. It then develops two link blocking models, an exact model based on the stochastic knapsack problem and an approximation model based on an approximate continuous time Markov chain (CTMC). The end-to-end performance analysis is conducted using the reduced load approximation. The result obtained from analysis is shown to be accurate compared with the numerical result obtained from simulation. 相似文献
17.
Traffic grooming for survivable WDM networks - shared protection 总被引:4,自引:0,他引:4
Canhui Ou Keyao Zhu Hui Zang Sahasrabuddhe L.H. Mukherjee B. 《Selected Areas in Communications, IEEE Journal on》2003,21(9):1367-1383
We investigate the survivable traffic-grooming problem for optical mesh networks employing wavelength-division multiplexing (WDM). In the dynamic provisioning context, a typical connection request may require bandwidth less than that of a wavelength channel, and it may also require protection from network failures, typically fiber cuts. Based on a generic grooming-node architecture, we propose three approaches for grooming a connection request with shared protection: protection-at-lightpath level (PAL); mixed protection-at-connection level (MPAC); separate protection-at-connection level (SPAC). In shared-mesh protection, backup paths can share resources as long as their corresponding working paths are unlikely to fail simultaneously. These three schemes explore different ways of backup sharing, and they trade-off between wavelengths and grooming ports. Since the existing version of the problem for provisioning one connection request with shared protection is NP-complete, we propose effective heuristics. Under today's typical connection-bandwidth distribution where lower bandwidth connections outnumber higher bandwidth connections, we find the following: 1) it is beneficial to groom working paths and backup paths separately, as in PAL and SPAC; 2) separately protecting each individual connection, i.e., SPAC, yields the best performance when the number of grooming ports is sufficient; 3) protecting each specific lightpath, i.e., PAL, achieves the best performance when the number of grooming ports is moderate or small. 相似文献
18.
In recent years, minimization of add-drop multiplexers (ADMs) in wavelength division multiplexing (WDM) optical networks has gained lots of attention in both the research and commercial areas. This motivates the research presented in this paper. A heuristic algorithm is formulated for static traffic grooming in WDM uni-directional ring networks with an eye to minimize the number of required ADMs. The distinguished feature of the proposed heuristic is that it pairs up the calls of a given static traffic to approach the solution. The proposed heuristic is compared with the previous approach with same network configuration and traffic matrix to establish its effectiveness. 相似文献
19.
In Wavelength Division Multiplexing (WDM) networks, the huge capacity of wavelength channels is generally much larger than the bandwidth requirement of individual traffic streams from network users. Traffic grooming techniques aggregate low-bandwidth traffic streams onto high-bandwidth wavelength channels. In this paper, we study the optimization problem of grooming the static traffic in mesh Synchronous Optical Network (SONET) over WDM networks. The problem is formulated as a constrained integer linear programming problem and an innovative optimization objective is developed as network profit optimization. The routing cost in the SONET and WDM layers as well as the revenue generated by accepting SONET traffic demands are modelled. Through the optimization process, SONET traffic demands will be selectively accepted based on the profit (i.e., the excess of revenue over network cost) they generate. Consiering the complexity of the network optimization problem, a decomposition approach using Lagrangian relaxation is proposed. The overall relaxed dual problem is decomposed into routing and wavelength assignment and SONET traffic routing sub-problems. The subgradient approach is used to optimize the derived dual function by updating the Lagrange multipliers. To generate a feasible network routing scheme, a heuristic algorithm is proposed based on the dual solution. A systematic approach to obtain theoretical performance bounds is presented for an arbitrary topology mesh network. This is the first time that such theoretical performance bounds are obtained for SONET traffic grooming in mesh topology networks. The optimization results of sample networks indicate that the roposed algorithm achieves good sub-optimal solutions. Finally, the influence of various network parameters is studied. 相似文献
20.
《Networking, IEEE/ACM Transactions on》2008,16(5):1226-1238