ISP’s Internet Backbone Augmentation using Virtual Link Configuration in Link-state Routing

Abstract

This paper addresses the backbone augmentation problem arising from ISP’s hierarchical link-state routing operations. Focusing on Virtual Link (VL) configuration, proposed is an efficient augmentation scheme of increasing redundancy of the original backbone topology. A VL restores hidden information from introducing hierarchy in the topological database of each backbone router, thereby increasing redundancy of the backbone and preventing partition of the backbone even if some links fail. With given potential VL locations and the original backbone topology, we propose a bi-objective efficient VL configuration model that explicitly evaluates the benefit side as well as the cost side of VL configurations, and fully leverages the trade-off between both sides. Furthermore, provided is an efficient branch-and-bound algorithm (implicit enumeration) with good lower and upper bounds so that solution speed can be accelerated in most cases. To our knowledge, this is the first try to attack the VL configuration problem systematically. For an ISP with its own domain, the proposed model and algorithm are expected to relieve network administrators burden of configuring VLs, support making the backbone more tolerable to backbone link failures, and finally, provide a practical vehicle for reliable link-state hierarchical routing indispensable to overall service quality.