Dual Link Failure Resiliency through Backup Path Mutual Exclusion

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 Description:

    The ever-increasing transmission speed in the communication networks calls for efficient fault-tolerant network design. Today’s backbone networks employ optical communication technology involving wavelength division multiplexing

(WDM). A link between two nodes comprises of multiple fibers carrying several tens of wavelengths with transmission speed on a wavelength at 40 Gb/s. Due to the large volume of information transported, it is necessary to reduce the resource unavailability time due to failures. Hence, efficient and fast recovery techniques from node and link failures are mandated in the design of high-speed

  networks.  As link failures are the most common case of the failures seen in the networks, this paper restricts its   scope to link failures alone.

 Optical networks of today operate in a circuit-switched manner as optical header processing and buffering technologies are still in the early stages of research for wide-scale commercial deployment. Protecting the circuits or connections

 established  in such networks against single-link failures may be achieved in two ways: path protection or link protection.

Path protection attempts to restore a connection on an end-to-end

basis by providing a backup path in case the primary (orworking) path fails.

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.

Existing System:

     Due to the large volume of information transported, it is necessary to reduce the resource unavailability   time due to failures. Hence, efficient and fast recovery techniques from node and link failures are mandated in the design of high-speed networks. Link protection recovers from a single link failure by    re-routing 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.

Proposed System:

§   Dual-link failure resiliency strategies are classified based on the nature in which the connections are recovered from first and second failures this project develops the necessary theory to prove the sufficient conditions for the existence of a solution to the BLME problem. Solution methodologies to the BLME problem are developed using two approaches by:

1)      formulating the BLME problem as an integer linear program (ILP)

2)      Developing a polynomial time heuristic algorithm based on minimum cost path routing.

System Requirements:

Hardware Requirements
Hard disk                  :           40GB
RAM                           :           265MBormore
Processor Speed       :           3.00GHz
Processor                  :           Pentium III Processor or  more

       Software Requirements

Ø  JDK1.5

Ø  Java Swing

Ø  SQL 2000