On stacking bi-directional self-healing-rings on a conduit ring

In this paper, we consider a network design problem of stacking multiple bi-directional self-healing-rings (BSHRs) on a given physical conduit ring in order to meet given demand requirements. The objective is then to find a cost-minimizing solution which not only specifies how many and what kinds of BSHR rings to install, but also indicates how to split the demand requirements among the installed BSHRs. The problem has been formulated as an IP model and then reformulated to a set-partitioning model via the column generation approach. An iterative solution method of alternating between two phases of generating and fixing columns was developed and tested with three different demand patterns. Computational experience gained from a total of more than 100 test runs for each demand pattern strongly supports the real-world applicability of the proposed model and the solution method. q 2003 Elsevier Science Ltd. All rights reserved.