Approximating Some Network Design Problems with Node Costs
APPROX '09 / RANDOM '09 Proceedings of the 12th International Workshop and 13th International Workshop on Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques
Tree embeddings for two-edge-connected network design
SODA '10 Proceedings of the twenty-first annual ACM-SIAM symposium on Discrete Algorithms
Approximating fault-tolerant group-Steiner problems
Theoretical Computer Science
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We consider approximation algorithms for buy-at-bulk network design, with the additional constraint that demand pairs be protected against edge or node failures in the network. In practice, the most popular model used in high speed telecommunication networks for protection against failures, is the so-called 1+1 model. In this model, two edge or node-disjoint paths are provisioned for each demand pair. We obtain the first non-trivial approximation algorithms for buy-at-bulk network design in the 1+1 model for both edge and node-disjoint protection requirements. Our results are for the single-cable cost model, which is prevalent in optical networks. More specifically, we present a constant-factor approximation for the single-sink case, and an {\rm O}(\log ^3 n) approximation for the multi-commodity case. These results are of interest for practical applications and also suggest several new challenging theoretical problems.