Algorithms for determining a node-disjoint path pair visiting specified nodes

Abstract

The problem of calculating the shortest path that visits a given set of nodes is at least as difficult as the traveling salesman problem, and it has not received much attention. Nevertheless an efficient integer linear programming (ILP) formulation has been recently proposed for this problem. That ILP formulation is firstly adapted to include the constraint that the obtained path can be protected by a node-disjoint path, and secondly to obtain a pair of node disjoint paths, of minimal total additive cost, each having to visit a given set of specified nodes. Computational experiments show that these approaches, namely in large networks, may fail to obtain solutions in a reasonable amount of time. Therefore heuristics are proposed for solving those problems, that may arise due to network management constraints. Extensive computational results show that they are capable of finding a solution in most cases, and that the calculated solutions present an acceptable relative error regarding the cost of the obtained path or pair of paths. Further the CPU time required by the heuristics is significantly smaller than the required by the used ILP solver.

LARAC-SN and Mole in the Hole: Enabling Routing through Service Function Chains

“…That is, the set of specified nodes can be visited in any order. Recent work also studied this problem [12]- [15]. In this paper, we consider that the order in which the nodes have to be visited is fixed.…”

“…Several papers propose a special-purpose algorithm for dealing with the SNE of specific problems [9]- [15], [18]- [21]. Our proposed LARAC-SN algorithm falls into this category for the constrained shortest path (CSP) problem.…”

Enhanced method of fast re-routing with load balancing in software-defined networks

“…When solving the fast re-routing problem in SDN, we use the functional model described in [23][24][25]. It belongs to the class of flow-based solutions and focuses on the optimal use of available network resources during the process of routing in network.…”

“…This is primarily because the calculation of the required routes is carried out on the SDN-controllers, mainly centralized by solving quite complex computationally optimization problems [13][14][15][16][17][18][19][20][21][22][23][24][25]. Implementation of the same principles of fault-tolerant routing is characterized by the fact that along with many primary routes it is necessary to calculate the backup paths using various schemes for protecting network elements: a link, a node or a path.…”

“…As shown by the analysis, on the one hand, the need to calculate a set of backup paths along with the primary routes implies a significant increase in the dimensionality of the formulated optimization problem [23][24][25]. On the other hand, the formalization of path protection schemes and their bandwidth also, as a rule, leads to a nonlinear formulation of the problem [24,25].…”