This is the remote Label Switch Router identifier component of the same composite TE-tunnel index, identifying the tail-end router of the outer tunnel carrying this pseudowire's outbound traffic, and it's zero when there's no TE tunnel involved. Comparing this against the pseudowire's actual intended far-end PE confirms the TE tunnel is actually heading toward the right destination for this VC rather than some other TE-tunnel endpoint sharing the same tunnel number. A mismatch here would explain a pseudowire that signals successfully but somehow ends up on the wrong physical path across the core.