297 research outputs found
Heuristic Solution to Protect Communications in WDM Networks using P-cycles
Optical WDM mesh networks are able to transport huge amount of information.
The use of such technology however poses the problem of protection against
failures such as fibre cuts. One of the principal methods for link protection
used in optical WDM networks is pre-configured protection cycle (p-cycle). The
major problem of this method of protection resides in finding the optimal set
of p-cycles which protect the network for a given distribution of working
capacity. Existing heuristics generate a large set of p-cycle candidates which
are entirely independent of the network state, and from then the good sub-set
of p-cycles which will protect the network is selected. In this paper, we
propose a new algorithm of generation of p-cycles based on the incremental
aggregation of the shortest cycles. Our generation of p-cycles depends on the
state of the network. This enables us to choose an efficient set of p-cycles
which will protect the network. The set of p-cycles that we generate is the
final set which will protect the network, in other words our heuristic does not
go through the additional step of p-cycle selectio
Unidirectional Quorum-based Cycle Planning for Efficient Resource Utilization and Fault-Tolerance
In this paper, we propose a greedy cycle direction heuristic to improve the
generalized redundancy quorum cycle technique. When applied using
only single cycles rather than the standard paired cycles, the generalized
redundancy technique has been shown to almost halve the necessary
light-trail resources in the network. Our greedy heuristic improves this
cycle-based routing technique's fault-tolerance and dependability.
For efficiency and distributed control, it is common in distributed systems
and algorithms to group nodes into intersecting sets referred to as quorum
sets. Optimal communication quorum sets forming optical cycles based on
light-trails have been shown to flexibly and efficiently route both
point-to-point and multipoint-to-multipoint traffic requests. Commonly cycle
routing techniques will use pairs of cycles to achieve both routing and
fault-tolerance, which uses substantial resources and creates the potential for
underutilization. Instead, we use a single cycle and intentionally utilize
redundancy within the quorum cycles such that every point-to-point
communication pairs occur in at least cycles. Without the paired
cycles the direction of the quorum cycles becomes critical to the fault
tolerance performance. For this we developed a greedy cycle direction heuristic
and our single fault network simulations show a reduction of missing pairs by
greater than 30%, which translates to significant improvements in fault
coverage.Comment: Computer Communication and Networks (ICCCN), 2016 25th International
Conference on. arXiv admin note: substantial text overlap with
arXiv:1608.05172, arXiv:1608.05168, arXiv:1608.0517
Design of survivable WDM network based on pre-configured protection cycle
Wavelength Division Multiplexing (WDM) is an important technique which allows the trans- port of large quantities of data over optical networks. All optical WDM-based networks have been used to improve overall communication capacity and provide an excellent choice for the design of backbone networks. However, due to the high traffic load that each link can carry in a WDM network, survivability against failures becomes very important. Survivability in this context is the ability of the network to maintain continuity of service against failures, since a failure can lead to huge data losses. In recent years, many survivability mechanisms have been studied and their performance assessed through capacity efficiency, restoration time and restorability. Survivability mechanisms for ring and mesh topologies have received particular attention
Protection and restoration algorithms for WDM optical networks
Currently, Wavelength Division Multiplexing (WDM) optical networks play a major role in supporting the outbreak in demand for high bandwidth networks driven by the Internet. It can be a catastrophe to millions of users if a single optical fiber is somehow cut off from the network, and there is no protection in the design of the logical topology for a restorative mechanism. Many protection and restoration algorithms are needed to prevent, reroute, and/or reconfigure the network from damages in such a situation. In the past few years, many works dealing with these issues have been reported. Those algorithms can be implemented in many ways with several different objective functions such as a minimization of protection path lengths, a minimization of restoration times, a maximization of restored bandwidths, etc. This thesis investigates, analyzes and compares the algorithms that are mainly aimed to guarantee or maximize the amount of remaining bandwidth still working over a damaged network. The parameters considered in this thesis are the routing computation and implementation mechanism, routing characteristics, recovering computation timing, network capacity assignment, and implementing layer. Performance analysis in terms of the restoration efficiency, the hop length, the percentage of bandwidth guaranteed, the network capacity utilization, and the blocking probability is conducted and evaluated
Efficient p-Cycle Design by Heuristic p-Cycle Selection and Refinement for Servivable WDM Mesh Networks
Using p-Cycles to protect against single span failures in Wavelength-Division Multiplexing (WDM) networks has been widely studied. p-Cycle retains not only the speed of ring-like restoration, but also achieves the capacity efficiency over mesh networks. However, in selecting an optimal set of p-cycles to achieve the minimum spare capacity and fast computational time is an NP-hard problem. To address this issue, we propose a heuristic approach to iteratively select and refine a set of p-cycles, which contains two algorithms: the Heuristic p-Cycle Selection (HPS) algorithm, and the Refine Selected Cycles (RSC) algorithm. Our simulation results show that the proposed approach is within 3.5% redundancy difference from the optimal solution with very fast computation time even for large networks
Survivable mesh-network design & optimization to support multiple QoP service classes
Every second, vast amounts of data are transferred over communication systems around the world, and as a result, the demands on optical infrastructures are extending beyond the traditional, ring-based architecture. The range of content and services available from the Internet is increasing, and network operations are constantly under pressure to expand their optical networks in order to keep pace with the ever increasing demand for higher speed and more reliable links
A new ILP-based p-cycle construction algorithm without candidate cycle enumeration
The notion of p-cycle (Preconfigured Protection Cycle) allows capacity efficient schemes to be designed for fast span protection in WDM mesh networks. Conventional p-cycle construction algorithms need to enumerate/pre-select candidate cycles before ILP (Integer Linear Program) can be applied. In this paper, we propose a new algorithm which is only based on ILP. When the required number of p-cycles is not too large, our ILP can generate optimal/suboptimal solutions in reasonable amount of running time. © 2007 IEEE.published_or_final_versio
Practical issues for the implementation of survivability and recovery techniques in optical networks
A Hybrid p-Cycle Search Algorithm for Protection in WDM Mesh Networks
p-Cycle is a type of shared link protection for survivable wavelength-division multiplexing (WDM) mesh networks. p-Cycle not only retains ring-like restoration speeds, but also achieves capacity efficiency in mesh networks. However, finding the optimal set of p-cycles to protect all traffic demands within a reasonable response time is difficult. This is particularity true with dense meshes or large networks, because the number of candidates is huge. Generally, p-cycles are determined by using either Integer Linear Programming (ILP) or specifically designed heuristic algorithms. However, both methods need a set of efficient candidate cycles to tradeoff between the computational time and the optimality of solutions. For this reason, constructing an efficient set of candidate p-cycles is crucial and imperative. In this paper, we propose the Span-weighted Cycle Searching (SCS) algorithm to generate and select an adequate number of p-cycles to minimize the spare capacity, while achieving 100% restorability, within low computational complexity
- …