Each PLR signals a detour LSP that avoids the downstream node. If the downstream node cannot be avoided, a detour LSP that avoids the downstream link is signaled.

The detour LSP can take one or more hops before merging back on the protected LSP.

The merge point of the protected LSP must be the next-next-hop node

The ingress router will set the local protection desired flag in the session attribute object of the path message to inform all routers along the protected LSP path to establish detour LSPs.

The label recording desired flag must be set in the session attribute object in order for the PLR to know what label to swap when using the detour LSP.