Efficiently grooming low-rate traffic flows into high-capacity lightpaths will improve the network throughput and resource utilization. In this paper, we study the traffic -grooming algorithm for WDM mesh networks. A novel dynamic grooming graph is proposed, which models the number of transceivers per node and the number of wavelength per fiber in addition to the combined information of IP layer and WDM layer, while taking into account the constraints of wavelength continuity in optical domain. Based on the grooming graph, a new dynamic traffic-grooming algorithm, namely Integrated Grooming Algorithm (IGA), is developed to provide an efficient solution to the traffic-grooming problem in WDM optical mesh networks. This algorithm is evaluated via simulations and results reveal that satisfactory performance of the proposed algorithms can be achieved.
This paper investigates the problem of dynamically establishing dependable connections in traffic-grooming wavelength division multiplexing (WDM) mesh networks, and proposes a dynamic shared sub-path protection (SSPP) scheme for multi-granularity traffic. To establish a dependable connection, SSPP searches a primary path for each connection request, and then it segments the found path into several equal-length sub-paths, and computes their corresponding backup paths, respectively. In SSPP, if two sub-paths are fiber-disjoint then their backup paths can share backup resources to obtain the optimal spare capacity. Based on dynamic traffic with different load, the performance of SSPP has been investigated via simulations. The results show that SSPP can make the tradeoffs between the resource utilization and the restoration time.
Optical fiber links, due to sharing some common physical resources, e.g., fiber cable, conduit and Right of Way, have certain failure-dependent. The term "Shared Risk Link Groups (SRLG)" is introduced to describe the relationship between links with shared risk; SRLG diversity has become the important constraint of protection design problem. This paper addresses SRLG-constraint-based shared-path protection design problem with differentiated reliability. Via
SRLG conditional failure probability concept, we propose an efficient PSD-SPP (Partial SRLG-disjoint Shared-Path Protection) algorithm to solve the protection design problem with differentiated reliability under the consideration of links failure-dependence. Simulation result shows that this algorithm not only efficiently satisfies the user-specific requirement, but also effectively decreases the network-blocking ratio.
In WDM networks, the bandwidth request of a traffic stream is usually much lower than the capacity of a wavelength. Traffic grooming can aggregate low-rate connections onto high-capacity lightpaths to make efficient use of the bandwidth. But most of the researches related to traffic grooming focused on ring networks, and fewer concerns are about the dependable traffic grooming of low-rate connections in WDM mesh networks. In our study, we present a Hamiltonian Cycle Protection based Traffic Grooming algorithm (HCPTG) considering both the survivability and traffic grooming in WDM mesh networks. Simulation results show that good performance can be achieved in terms of capacity efficiency.
This paper investigates the diverse routing in a wavelength division multiplexing (WDM)-based optical network under SRLG-disjoint constraints. In operational optical networks there are a lot of traffic flows within every lightpath. Any failure of one Iightpath will lead to a great loss. So we should provide path protection for the working lightpath. The concept of Shared Risk Link Groups (SRLG) is introduced in optical networks by IETF, which is defined as a group of links that share a common risk component whose failure can potentially cause the failure of all the links in the group. This concept groups all of the entities, such as wavelengths and links, etc., that are affected by a single failure. Now when path protection is employed, for any lightpath connection request, we compute two SRLG-disjoint lightpaths, one as working path and the other as protection path. There are some literatures, which propose methods for link-disjoint paths pair or node-disjoint paths pair, but few algorithms for SRLG-disjoint paths pair. The SRLG-disjoint constraints entail the general constraint-based path computation algorithms. Since this problem is an NIP-complete problem and there is no algorithm which could be used to solve this path computation in polynomial time. This paper presents a heuristic algorithm, Low-cost Pair of SRLG-Disjoint Paths Algorithm (LPSD), to solve this problem. LPSD can compute two SRLG-Disjoint paths simultaneously, and the total cost of the two paths is near optimal. Analysis and simulation are also given out.
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