LDP Label Withdrawal Timer

The label withdrawal timer delays sending a label withdrawal message for a forwarding equivalence class (FEC) to a neighbor. When an interior gateway protocol (IGP) link to a neighbor fails, the label associated with the FEC has to be withdrawn from all the upstream routers if the neighbor is the next hop for the FEC. After the IGP converges and a label is received from a new next hop, the label is readvertised to all the upstream routers. This is the typical network behavior. By delaying label withdrawal by a small amount of time (for example, until the IGP converges and the router receives a new label for the FEC from the downstream next hop), withdrawing the label and sending a label mapping soon could be avoided. If the router receives the new label before the timer runs out, the label withdrawal timer is canceled. However, if the timer runs out, the label for the FEC is withdrawn from all of the upstream routers. By default, LDP waits for 60 seconds before withdrawing labels to avoid resignaling label-switched paths (LSPs) multiple times while the IGP is reconverging. You can modify the label withdrawal timer by making configuration changes, if required in a particular deployment.