Citation Context

...ificantly large adverse impact on the economy. In the last few years researchers have been examining survivability issues in WDM networks [1], [2], [5], [7], [14], [17], [18], [19], [20], [22], [23], =-=[27]-=-, [31], [32], [33]. Two techniques, protection at the WDM layer and restoration at the IP layer have emerged as the two main contenders for fault management in optical networks [21], [26]. Protection ...

Citation Context

...04 IEEE IEEE INFOCOM 2004sis minimized. We call it a Min-Min problem, as opposed to the Min-Sum problem above. The Min-Min problem is also different from the so-called Min-Max problem studied in [9], =-=[10]-=- where the objective was to minimize the length of the longer one of the two paths (to be used as a BP). Specifically, as another major contribution, we prove that the Min-Min problem above is also NP...

Citation Context

...e first shortest path negative. Shaikh [23] made an extension to Bhandari’s algorithm [1] to solve the span-disjoint paths problem in more complicated structured optical networks. It is proved in [16]=-=[22]-=- that the LPP problem will be NP-complete if it is required that the maximal length of the two disjoint paths, i.e. max(l(P1), l(P2)), is minimized. In addition, Ho and Mouftah [10] proposed another o...

Citation Context

...e online process of comparing relative costs of different primary-backup route candidates, it is still an inelegant bruteforce technique that could potentially be optimized. Efficient solutions exist =-=[42, 43, 39]-=- for the problem of finding the minimum-cost disjoint route-pair (MinCostPP), where the cost metric is simply the sum of weights for each link in the disjoint route-pair. The problem handled by LCBR h...

Citation Context

...int primary-backup path pair and assigning wavelength(s) to each path is known as the survivable routing and wavelength assignment (S-RWA) problem and has been extensively studied [1], [2], [7], [8], =-=[9]-=-. Typically, routing heuristics prefer the path pair with least cost from a source to a destination to carry the traffic, where the path cost is defined to be the sum of the costs of all the links alo...

Citation Context

...restoration methods have been studied and implemented for the mesh topology, such as automatic protection switching (APS), dedicated path protection, shared backup path protection (SBPP), p-cycles... =-=[28, 32, 41, 88, 89, 34]-=-. These 149 protection techniques have variations in terms of complexity, spare capacity usage and restoration speed. Thus, from the network designer’s perspective, each method has its own advantages ...

Citation Context

...-step approaches can be used to find the set of disjoint path-pairs. They are simple and computationally efficient. However, since these approaches provision traffic streams sequentially without back-tracking, sometimes no solution may be found even when a feasible solution does exist. In fact, the graph theory approach is more applicable 432 New Frontiers in Graph Theory www.intechopen.com Graph Theory for Survivability Design in Communication Networks 13 in online provisioning than in offline provisioning. These approaches have been extensively studied in the literature (Patre et al., 2002; Sen et al., 2001; Xin et al., 2002; Zhang et al., 2003). Authors in (Xin et al., 2002) investigated survivable routing based on both the two-step and the one-step approaches, namely Separate Path Selection (SPS) and Joint Path Selection (JPS) respectively. These approaches aim to optimise the network resource utilisation of each traffic connection by minimising the total cost of the primary and backup paths. The performance of these approaches is evaluated for different protection path cost functions. The results have shown that JPS performs substantially better than SPS and also scales very well in terms of ...

Citation Context

...graphical distance it has, is minimized. We call it a MinMin problem, as opposed to the Min-Sum problem above. The Min-Min problem is also different from the so-called MinMax problem studied in [10], =-=[11]-=- where the objective was to minimize the length of the longer one of the two paths (to be used as a BP). Specifically, as another major contribution, we prove that the Min-Min problem above is also NP...