MPLS local protection

[2][3][4][5][6] This node which redirects the traffic onto the preset backup path is called the Point of Local Repair (PLR), and the node where a backup LSP merges with the primary LSP is called Merge Point (MP).

For comparison, when recovery mechanisms are employed at the IP layer, restoration may take several seconds which is unacceptable for real-time applications (such as VoIP).

In contrast, MPLS local protection meets the requirements of real-time applications with recovery times comparable to those of shortest path bridging networks or SONET rings (< 50 ms).

Maintaining state information for backup paths protecting individual LSPs, as in the one-to-one approach, is a significant resource burden for the PLR.

Moreover, periodic refresh messages[7] sent by the PLR, in order to maintain each backup path, may become a network bottleneck.

Fig.1 Fast Reroute operation
An illustration of MPLS local protection Faults Modes. Note that complete network is not shown only primary and backup paths are shown. Furthermore, nodes traversed by a backup path are not shown.