Traffic Engineering with MPLS

Link Protection

Link protection can be divided into four sections:

• Prefailure configuration

• Failure detection

• Connectivity restoration

• Post-failure signalling

The following sections examine each of these topics in detail.

Prefailure Configuration

You need to note one subtle point: Link protection, like all other TE applications, is unidirectional. In order to protect LSPs flowing from A to B across a link, you need protection in the A→B direction. To protect LSPs flowing from B to A across the same link, you also need to build a protection LSP in the B→A direction. Most of the configurations or concepts presented in this chapter are unidirectional unless specified otherwise.

There are two places where you have to configure things related to link ...