The isis timer csnp command configures an interval at which CSNPs are sent on the broadcast network.
The undo isis timer csnp command restores the default value.
By default, the interval at which CSNPs are sent is 10 seconds.
| Parameter | Description | Value |
|---|---|---|
| csnp-interval |
Specifies an interval at which CSNPs are sent on a broadcast network. |
The value is an integer ranging from 1 to 65535, in seconds. |
| level-1 |
Indicates the interval at which Level-1 CSNPs are sent. |
- |
| level-2 |
Indicates the interval at which Level-2 CSNPs are sent. If neither Level-1 nor Level-2 is specified, by default, the interval at which the CSNPs of the current level are sent is set. |
- |
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Usage Scenario
On a broadcast network, a DIS sends CSNPs periodically to enable all devices to synchronize LSDBs with one another. If a device finds that the local LSDB does not have a specific LSP or an existing LSP is not the latest one after the device has received a CSNP, the device will send a PSNP to request the corresponding LSP.
The interval at which CSNPs are sent can be configured using the isis timer csnp command.Configuration Impact
The IS-IS route convergence speed depends on the LSDB synchronization speed. Therefore, reducing the interval at which CSNPs are sent can speed up LSDB synchronization and IS-IS route convergence. If the interval is set too small, the DIS will send CSNPs frequently. This causes high CPU, memory, and network bandwidth usage and affects services.
Precautions
Only the DIS can periodically send CSNPs. This command is valid only for the device that is elected as the DIS. The DIS can be a Level-1 and Level-2 DIS, and the intervals at which CSNPs are sent must be set respectively.
If the isis circuit-type command is run to emulate an interface as a P2P interface, the isis timer csnp command becomes invalid on the interface; after the undo isis circuit-type command is run to restore the broadcast interface, the interval at which CSNPs are sent is restored to the default value.