MPLS LDP-IGP synchronization provides a means to synchronize LDP and IGPs to minimize MPLS packet loss.
MPLS LDP-IGP synchronization also provides the following benefits:
MPLS LDP-IGP synchronization may be enabled on an interface or globally. LDP determines convergence (receipt of all labels) for a link through one of two methods:
The following figure provides an example of LDP-IGP synchronization.
When the LDP peer is not reachable, the IGP establishes the adjacency to enable the LDP session to be established. When an IGP adjacency is established on a link but LDP-IGP Synchronization is not yet achieved or is lost, the IGP advertises the maximum metric (max-metric) on the link.