18-10-2010, 10:00 AM
Dual Link Failure Resiliency through Backup Path Mutual Exclusion.ppt (Size: 684 KB / Downloads: 102)
Dual Link Failure Resiliency through
Backup Path Mutual Exclusion
Backup Path Mutual Exclusion
Abstract
Networks employ link protection to achieve fast recovery from link failures. While the first link failure can be protected using link protection, there are several alternatives for protecting against the second failure. This paper formally classifies the approaches to dual-link failure resiliency. One of the strategies to recover from dual-link failures is to employ link protection for the two failed links independently, which requires that two links may not use each other in their backup paths if they may fail simultaneously.
Such a requirement is referred to as backup link mutual Exclusion (BLME) constraint and the problem of identifying a backup path for every link that satisfies the above requirement is referred to as the BLME problem. This paper develops the necessary theory to establish the sufficient conditions for existence of a solution to the BLME problem. Solution methodologies for the BLME problem is developed using two approaches by
1) Formulating the backup path selection as an integer linear program
2) Developing a polynomial time heuristic based on minimum cost Path routing.
PROBLEM ANALYSIS:-
Link protection recovers from a single link failure by rerouting connections around the failed link.
Such a recovery may be achieved transparent to the source and destination of the connections passing through the failed link.
Algorithms for protection against link failures have traditionally considered single-link failures.
Dual link failures are becoming increasingly important due to two reasons.
First, links in the networks share resources and the failure of such shared resources result in the failure of multiple links.
Second, the average repair time for a failed link is in the order of a few hours to few days and this repair time is sufficiently long for a second failure to occur.