Design of a fast restoration mechanism for virtual path-based ATM networks

In this paper, we propose a fast restoration mechanism for virtual path-based ATM networks. Given an ATM network topology, the capacity of each physical link, and the primary virtual path (VP) layout at system initialization, the proposed mechanism pre-assigns to each primary VP one backup VP such that (P1) the failure of a single node/link does not lead to the failure of both the primary and backup VPs, (P2) the alternate backup VP is routed on a path with the shortest hop count among all possible paths with sufficient bandwidth between the two VP terminators, and (P3) the maximum link load is minimized. During system operation, if a physical node/link fails, the proposed mechanism restores the VPs that traverse the failed node/link simply by redirecting cells on the failed VPs to their corresponding backup VPs. Moreover, the proposed mechanism also locates (i) new VPs for injured backup VPs that traverse the failed node/link, and (ii) second-generation backup VPs for newly-activated backup VPs that replace their corresponding failed primary VPs, both in a decentralized manner. We elaborate on all the component algorithms, and discuss how to configure the functionalities as software daemons that reside at each network node. The proposed mechanism is shown via event-driven simulation to be practically feasible in fast restoring failed VPs in a cost effective manner.