Artificial Bee Colony model for routing and wavelength assignment problem

지난 수 십 년간 통신 기술의 발전과 웹 서비스의 팽창은 인터넷 사용자 수의 폭발적인 증가와 화상회의, 가상 증감 현실, 인터넷 게임 등 실시간 멀티미디어 멀티캐스트 서비스의 급격한 증가를 초래했다. 고밀도 파장분할다중화기술에 기반한 DWDM(Dense-Wavelength Division Multiplexing) 기술은 인터넷 사용자의 증가와 그에 따른 대역폭 요구를 수용하기 위한 방안으로 국가나 글로벌 영역 범위의 차세대 인터넷망 구현을 위한 백본망 기술로 여겨지며, 이러한 DWDM 전달망에서는 멀티캐스트 연결 요구에 대해 최적의 경로를 선택하고 선택된 경로에 효율적으로 파장을 할당하는 멀티캐스트 RWA(Routing and Wavelength Assignment) 문제가 파장 대역폭의 효율적인 활용 측면에서 매우 중요하게 다루어지고 있다. 주어진 파장 수 환경에서 최대한 많은 수의 멀티캐스트 연결을 달성하는 문제는 일반적으로 Non -deterministic Polynomial-time-complete 문제로 여겨지는 데, 본 논문에서는 가상소스를 기반으로 노드의 능력에 따른 차등화로 우선 순위를 적용하여 휴리스틱하게 멀티캐스트 라우팅 경로를 효율적으로 선정하는 DVS-PMIPMR (Differentiated Virtual Source-based Priority Minimum Interference Path Multicast Routing) 알고리즘을 제안한다. 마지막으로 같은 조건에서 더 많은 수의 멀티캐스트 라우팅 패스의 연결이 가능함을 시뮬레이션 및 성능분석 증명한다. Over the past decade, the improvement of communications technologies and the rapid spread of www (World Wide Web) have brought on the exponential growth of users using Internet and real time multimedia multicast services like video conferencing, tele-immersive virtual reality, and Internet games. The dense-wavelength division multiplexing (DWDM) networks have been widely accepted as a promising approach to meet the ever-increasing bandwidth demands of Internet users, especially in next generation Internet backbone networks for nation-wide or global coverage. A major challenge in the next generation Internet backbone networks based on DWDM technologies is the resolution of the multicasting RWA (Routing and Wavelength Assignment) problem; given a set of wavelengths in the DWDM network, we set up light-paths by routing and assigning a wavelength for each connection so that the multicast connections are set-upped as many as possible. Finding such optimal multicast connections has been proven to be Non-deterministic Polynomial-time-complete. In this paper, we suggest a new heuristic multicast routing and wavelength assignment method for multicast sessions called DVS-PMIPMR (Differentiated Virtual Source-based Priority Minimum Interference Path Multicast Routing algorithm). We measured the performance of the proposed algorithm in terms of number of wavelength and wavelength channel. The simulation results demonstrate that DVS-PMIPMR algorithm is superior to previous multicast routing algorithms.

The routing and wavelength assignment (RWA) problem is a classic and challenging problem in wavelength-division multiplexing (WDM) optical networks and has shown to be NP-hard. This paper studies the min-RWA problem with the objective of minimizing the number of required wavelengths and presents a new powerful neighborhood called Shift-and-Shaking (SAS). The proposed SAS integrates a high-level shift move to change the wavelength of one lightpath and two low-level ejection chain-based shaking (ECS) procedures to find the best routings for the related lightpaths. This new neighborhood is embedded into a simple iterated local search algorithm, called SAS-ILS, for solving min-RWA. The proposed SAS-ILS is tested on three sets of totally 113 widely studied instances in the literature. Comparison with other state-of-the-art algorithms shows that the SAS-ILS is able to improve 22 previous best known results, while matching the best known results for the remaining ones within short computational time.

This paper proposes the optimal design of lightpath Routing and Wavelength Assignment (RWA) problem in Wavelength Division Multiplexing (WDM) networks without wavelength conversion. We formulate RWA as a mixed Integer Linear Programming (ILP) problem where the objective is to minimize the cost of wavelength assignment to the fiber links in the network. The Lagrangean relaxation technique and the optimization-based heuristics are used to solve this problem. Two sets of computational experiments are performed to test the algorithms for the maximum carried traffic and minimum wavelength requirements in three different network topologies (GTE, ARPA, OCT network). Based on solution quality to the computational experiments, the error gaps between the upper bound and the lower bound are close enough that the near optimal solutions could be obtained. On the other hand, we also show that the solution quality degrade gracefully under more and more heavy traffic network environment. By assessing solution quality and the computational time, we propose the efficient and effective optimization-based algorithms based on the Lagrangean relaxation method for the RWA problem in the WDM networks without wavelength conversion.

In this paper, we compare performance of fixed-grid Wavelength Division Multiplexing (WDM) and Elastic Optical Networks (EONs) in dynamic provisioning of many-to-many (m2m) flows. Currently, with a growth of services relying on many-to-many communication paradigm such as distributed computing, inter-Data Center communication, content delivery networking or other requiring high-bandwidth in group communication, it is vital to deliver new solutions facilitating these demanding transmissions. Therefore, the authors investigate provisioning of m2m traffic in high-performance optical networks. This work focuses on dynamic Routing and Wavelength Assignment (RWA) problem in WDM networks as well as Routing and Spectrum Allocation (RSA) problem in EONs for m2m flows using replicated communication through auxiliary rendezvous servers.

In an all-optical WDM network; optical fibers are used to transmit data followed by WDM technology. An optical fiber carries light along its length path at high rates and with little loss. Several wavelengths on a single fiber can be used to transfer data, when using wavelength-division multiplexing. In this way, several data transmissions at very high speed can take place on a single fiber. The routing and wavelength assignment (RWA) problem consists of finding a path and a wavelength for a set of data connections. The objective is typically to maximize the profit of established data by achieving as much as possible lightpath for transmitting optical signal (max-RWA). The RWA is NP-hard, thus much research has been conducted to finding a good way of approaching the RWA. This work mainly focuses on the analyzes work RWA problem based on integer linear programming (ILP) and reliable heuristics for variant topology of WDM networks. For performance analysis heuristics method as well as others variants of solution for RWA problem also had been implemented which results give some interesting observation about resources as well as optimal solution.

This paper addresses the problem of routing and wavelength assignment (RWA) in multifiber WDM networks with limited resources. Given a traffic matrix, the number of fibers per link, and the number of wavelengths a fiber can support, we seek to maximize the carried traffic of connections. We formulate the problem as an integer linear program (ILP), and show that the lightpaths selected by this formulation can indeed be established by properly configuring the optical switches. An upper bound on the carried traffic can be computed by solving the linear programming (LP)-relaxation of the ILP formulation. It is shown that this bound can be also computed exactly, and in polynomial-time, by solving a significantly simplified LP which considers only one wavelength. The bound can, thus, easily scale to an arbitrarily large number of wavelengths. Furthermore, we demonstrate that any instance of the RWA problem is also an instance of the more general maximum coverage problem. This allows us to take a greedy algorithm for maximum coverage and obtain an algorithm which provides solutions for the RWA problem that are guaranteed to be within a factor of (1-(1/e)) of the optimal solution. Each iteration of the greedy algorithm selects a set of lightpaths that realizes, using one wavelength, the maximum number of connection requests not previously realized. Computational results confirm the high efficiency of our proposed algorithm.

In this paper we consider the routing and wavelength assignment problem in a wavelength routed all optical network. Inspired by techniques from artificial intelligence, in particular the Blocking Island (BI) abstraction, we propose a simple and intelligent routing and wavelength assignment (RWA) algorithm: BI_RWA. This algorithm can be used in arbitrarily connected optical networks. In addition, it is general enough such that with some simple modifications, it can be applied to different optical networking scenarios: static or dynamic traffic, single or multiple fiber links between node pairs, with or without wavelength converters. We have conducted simulation experiments to evaluate the performance of our algorithm. The simulation is carried out in two parts: static traffic and dynamic traffic. The results will demonstrate that our RWA algorithm outperforms state-of-the-art related algorithms.

For WDM networks with multi-granularity switching, optical tunnel allocation (OTA) deals with the real-time establishment of optical tunnels between optical nodes through various optical multi-granularity switching devices. OTA is in principle a dynamic routing and wavelength assignment (RWA) problem with multi-granularity switching devices taken into account. In this paper, we propose a novel approximation approach, called Lagrangean relaxation with heuristics (LRH), aimed to resolve RWA considering both fiber and lambda switches. Such RWA is first formulated as a combinatorial optimization problem in which the bottleneck link utilization is to be minimized. To tackle the problem, the LRH approach performs constraint relaxation and derives a lower-bound solution index according to a set of Lagrangean multipliers generated through subgradient-based iterations. In parallel, using the generated Lagrangean multipliers, the LRH approach employs a new heuristic algorithm to arrive at a near-optimal upper-bound solution. Through numerical results and comparisons, we delineate that the LRH approach achieves a near-optimal solution, which is profoundly tight to its lower bound, at the expense of low computational time complexity.

WDM networks are increasingly gaining popularity as the backbone networks all over the world. In WDM network planning, electronic equipments like ADMs contribute heavily towards the capital expenditure of the network (Each ADM costs $50,000-$200,000). In WDM rings, determining minimum number of ADMs is NP-Hard. All the previous works have focused on Wavelength Assignment problem by keeping the routing fixed. In this paper, we suggest an integrated topology independent procedure called M3AWI (Minimum Average Minimum Weight Minimum Intersection). M3AWI is used to solve problems on four different types of routing namely, clockwise routing, Anti-clockwise routing, shortest-path routing, and hybrid routing. Our experimental results show that the combined Routing and Wavelength assignment (RWA) algorithms on an average save around 10% of the ADMs.We have also shown that the distribution of lightpaths is an important parameter to the service providers for selecting a routing policy.

We study the routing and wavelength assignment (RWA) problem in multi-segment optical networks. In these networks, each segment has different resource availability or hardware characteristics. The differences between multi-segment optical networks and homogeneous optical networks are discussed. We then present a resource abstraction technique called blocking island and define a multi-segment BIG (blocking island graph) network model. Using a minimum splitting routing heuristic introduced in the context of the blocking island paradigm in conjunction with the multi-segment BIG model, we propose a general RWA algorithm that takes a combined view of the network resource to integrate routing, wavelength assignment and gateway selection in a single routing framework. Using simulation, we demonstrate the effectiveness of our proposed algorithm by comparing it with other state-of-the-art heuristics in this area.

In Optical Burst Switching (OBS) networks, one of the main problems is collision between bursts. Most of the previous collision avoidance algorithms divide the Routing and Wavelength Assignment (RWA) problem into two partial problems and treat them separately. This paper focuses on the collision avoidance problem in distributed OBS networks. Our proposal involves cooperation between the routing and the wavelength assignment tasks. The main idea is to classify each wavelength at an output link of a node as suited either to sending or to relaying data bursts. The wavelength most suitable for transmitting bursts changes along the transmission route. Thus, we introduced a novel index called the Suitability Index (SI). The SI is a priority index assigned to each pair of output link and wavelength, and its value represents the suitability of that pair for sending or relaying data bursts. The proposed method uses the SI for both routing selection and wavelength assignment. Simulation results show that the proposed method can reduce the burst loss probability, particularly for long distance transmissions. As a result, unfairness in the treatment of short hop and long hop bursts can be reduced.

The advent of WDM technology has resulted in transmission capacities that have increased manifold in recent years. The most common architecture used for establishing communication in WDM optical networks is wavelength routing, where data are transmitted over all-optical WDM channels, called lightpaths, which may span multiple consecutive fibers. A lightpath is realized by determining a path between the source and the destination and allocating a free wavelength on all the links of the path. The selection of the path and the wavelength to be used by a lightpath is an important optimization problem, known as the routing and wavelength assignment (RWA) problem (Ramaswami & Sivarajan, 1995). In the absence of wavelength conversion, a lightpath must be assigned a common wavelength on each link it traverses; this restriction is referred to as the wavelength continuity constraint. However, two lightpaths may occupy the same wavelength, as long as they use disjoint sets of links; this property is known as wavelength reuse. The RWA problem is usually considered under two alternative traffic models. Static Lightpath Establishment (SLE) addresses the case where the set of connections is known in advance and Dynamic Lightpath Establishment (DLE) considers the case where connection requests arrive randomly, over an infinite time horizon, and are served one-by-one.

In this chapter we study the planning (offline) problem in WDM networks. In such networks, the signal quality of transmission (QoT) degrades due to physical-layer impairments, making necessary the use of regeneration at some intermediate nodes for certain lengthy lightpaths. Because of physical effects, routing choices made for one lightpath affect and are affected by the choices made for the other lightpaths. This interference among the lightpaths is particularly difficult to formulate in a planning algorithm, since in this version of the problem, we start without any established connections, and the utilization of lightpaths is the variable of the problem. We present a way to formulate inter-lightpath interference as additional constraints on the routing and wavelength assignment (RWA) problem. We initially present algorithms to solve the problem of planning a transparent all-optical WDM network, that is, a WDM network without regeneration capability. Then, we turn our attention to translucent WDM optical networks and present a series of algorithms that choose the regeneration sites and the number of regenerators required on these sites, solving the regenerator placement and the RWA problem for a given set of requested connections.

The foreseeable lightpath demands (FLD) include scheduled lightpath demands (SLD) and predictable lightpath demands (PLD, lightpath demands that can be approximatively forecasted through the history traffic record). Since the time disjointness each FLD, the network planner can design the capacity of the network more compactly. We formulate the routing and wavelength assignment (RWA) problem when network dimensioning is coupled as the Integer linear programming (ILP) which includes the link formulation and path formulation. To reduce the computing complexity, a new routing algorithm based on the consideration of backup path is proposed. The software experiment is run and shows that the gain is about 20% when the backup path needs to be setup. At last we propose a new RWA algorithm to adapt the FLDs and dynamic traffic into the wavelength routing network.

A post-optimization method for the routing and wavelength assignment problem applied to scheduled lightpath demands