Optimal and guaranteed alternative LSP for multiple failures

Abstract

Absfrmf-Fast rerouting mechanism are being studied in order to protection techniques. The pre-established altemative LSP is better provide fault tolerance for U P in an MPLS network in ease Of node Or link failure. For QoS promion protected LSP -e handled apart from non-protected LSP. Rerouting mechanisms when applied on protected Lsp tske into Becount QoS This paper presents a mechanism that is able to handle multiple failure a~onp, an LSP while for critical traffic than the alternative LSp established on demand after the occurrence of failure [6], [7]. several schemes haye bee,, proposed for selecting the best route(s) from several candidates based on different criteria [91,[101,[111. using an optimal alternative LSP. The &outing decision is taken close to the point of failure reducing the restoration time. The use of preestablkhed alternative LSP also reduces the restoration time and avoids blocking when looking for an alternative path. The proposal is based on B hybrid approach of segment repair and path repair and provides a new alternative LSP using dynamic rerouting once the protected one has been rerouted. In this way there is always an sltemative I S P for each protected LSP. The oyer all perlomanee (recovery time, end-to. end delay, packet losses, and network resource utilization) b compared with existing protection mechanisms by simulation. The proposed hybrid approach, Optimal and Guaranteed Allemalive Path (OGAP), avoids the possible use of a non-optimal alternative LSP to reroute the protected traffic and provides the flexibility of alternative mute selection and setup as well as better resource utilization. Moreover, our proposal guarantees st least one alternative LSP at any time for the trafiie on the pmteeted LSP.