The timer lsp-refresh command sets the interval for updating LSPs.
The undo timer lsp-refresh command restores the default setting.
By default, the interval for updating LSPs is 900 seconds.
| Parameter | Description | Value |
|---|---|---|
refresh-time |
Specifies the interval for updating LSPs. |
The value is an integer that ranges from 1 to 65534, in seconds. |
Usage Scenario
On an IS-IS network, LSDB synchronization is implemented through LSP flooding. During LSP flooding, a device sends an LSP to its neighbors and then the neighbors send the received LSP to their respective neighbors except the device that first sends the LSP. In this manner, the LSP is flooded among the devices of the same level. LSP flooding allows each device of the same level to have the same LSP information and synchronize its LSDB with each other.
LSPs need to be periodically flooded. When the system generates the system LSP, the system fills in the LSP with its maximum lifetime. After other devices receive this LSP, the lifetime of the LSP is reduced accordingly. If the device does not receive an updated LSP, the lifetime of the LSP is reduced to 0, and the device retains the LSP for another 60 seconds. If the device still does not receive any updated LSP within 60 seconds, the device deletes the LSP.
You can run the timer lsp-refresh command to set the interval for updating LSPs to control network convergence speed.
Precautions
If the interval for updating LSPs is small, LSPs may be updated frequently, which occupies a lot of bandwidth. If the interval is long, routing information changes cannot be notified in a timely manner.