The label-withdraw-delay timer command sets the delay time before a node sends a Label Withdraw message.
The undo label-withdraw-delay timer command restores the default delay time.
The default delay time is 5 seconds.
| Parameter | Description | Value |
|---|---|---|
| time | Specifies the delay time before a Label Withdraw message can be sent. |
The value is an integer ranging from 1 to 65535, in seconds. The default value is 5 seconds, which is recommended. |
Usage Scenario
If an LDP label switched path (LSP) fails because of a route change on a node, to enable the node to notify the ingress of the fault location and cause, the label-withdraw-delay command must be run on each node on the LSP to delay sending Label Withdraw messages. The label-withdraw-delay timer command can be used to set the delay time before a node can send a Label Withdraw message to its upstream node.
The label withdraw delay function prevents downstream LSP flapping from spreading to upstream nodes. For example, an LSP on a local node flaps because an LDP session between the node and its downstream peer flaps, a route flaps, or an LDP policy is modified. The local node repeatedly sends Label Withdraw and Label Mapping messages in sequence to upstream nodes. This causes the upstream nodes to repeatedly tear down and reestablish LSPs. As a result, the entire LDP LSP flaps. To suppress the spread of LSP flapping, run the label-withdraw-delay command to enable the label withdraw delay function on each node and the label-withdraw-delay timer command to set the delay time before a node sends a Label Withdraw message to its upstream node.
Prerequisites
The label withdraw delay function has been enabled using the label-withdraw-delay command.