Survivable networks based on optimal routing and WDM self-healing rings

Abstract

The design of survivable all-optical networks based on self-healing WDM rings (SHR/WDM) to provide 100% protection from any single link failure requires the joint solution of three sub-problems. These are the ring cover of the mesh topology (the RC sub-problem), the routing of working lightpaths between node pairs to support traffic demands (the WL sub-problem) and the selection of the SHR/WDM spare wavelengths for the protection of every link traffic (the SW subproblem). This paper presents an integer linear programming (ILP) formulation of the problem of minimizing the total wavelength mileage (λ-miles) required to support a set of given traffic demands in a given network topology using SHR/WDM employing 1:N line protection mechanism (the WRL problem). This formulation allows to jointly and optimally solve the three subproblems, and yields up to 15% reduction of the total λ-miles required by existing solutions that separately resolve the sub-problems. A simplified sub-optimal solution of the WRL problem is also provided, that yields results few percent worse than the optimal solution and that is tractable for networks whose size is on the order of the pan-European network, i.e., 19 nodes

Dynamic lightpath protection in WDM mesh networks under wavelength-continuity and risk-disjoint constraints

“…In protection schemes, backup resources are pre-computed and reserved for each connection before a failure occurs [5] [6]. In restoration schemes, an alternate route is discovered dynamically for each interrupted connection after a failure occurs [7] [8].…”

Design and operation of mesh-restorable WDM networks

“…In [50], randomized rounding technique was used to convert fractional flows provided by the LP solution to integer flows, and graph coloring algorithms were used to assign wavelengths to the lightpaths. The problem of minimizing the total wavelength mileage, in a network with arbitrary topology, to provide shared line protection was studied in [53]. In [54], the authors proposed an efficient approach for solving the wavelength mileage problem.…”

Designing physical topologies that enable survivable routing of logical rings

“…The five logical links of this ring can be routed on the physical topology as shown in Figure 1a, where each physical link is labeled with the logical link that traverses it. For example logical link (1,3) traverses physical links (1,5) and (5,3). As can be seen from the figure, no physical link supports more than one logical link.…”

“…While there has been a great deal of work in the area of optical layer protection [1][2][3][4][5][6][7][8], this survivable routing formulation is a new approach to network protection that has significant implications on the design of future WDM-based networks. Most previous work in WDM network protection has focused on restoration mechanisms that restore all lightpaths in the event of a physical link failure.…”

“…Most previous work in WDM network protection has focused on restoration mechanisms that restore all lightpaths in the event of a physical link failure. Link based restoration recovers from a link failure by restoring the failed physical link, hence simultaneously restoring all of the associated lightpaths [1,2,5]. This is often done using optical loop-back protection [1,2,4].…”