Overview of LDP Reliability

Reliability measures are used to ensure the reliability of LSPs. LSPs are paths established through LDP.

LDP LSP reliability technologies are necessary for the following reasons:

If a node or link on a working LDP LSP fails, reliability technologies are used to establish a backup LDP LSP and switch traffic to the backup LDP LSP, while minimizing packet losses in the process.
If a node on a working LDP LSP encounters a control plane failure but the forwarding plane is still working, reliability technologies ensure traffic forwarding during fault recovery on the control plane.

MPLS provides multiple reliability technologies to ensure the high reliability of key services transmitted over LDP LSP. The following table describes the LDP reliability technologies.

**Table 1** LDP reliability technologies
Reliability Technology	Description	Function
Fault detection	Rapidly detects faults on LDP LSPs of an MPLS network and triggers protection switching.	BFD for LDP LSP
Traffic protection	Ensures traffic is switched to the backup LDP LSP and minimizes packet loss when the working LDP LSP fails.	Synchronization Between LDP and IGP
Traffic protection	Ensures nonstop forwarding on the forwarding plane when the control plane fails on a node.	LDP GR