The flash-flood command enables LSP fast flooding to speed up the convergence on IS-IS networks.
The undo flash-flood command disables LSP fast flooding.
By default, the LSP flash-flood feature is not enabled.
flash-flood [ lsp-count ] [ max-timer-interval interval ] [ level-1 | level-2 ] *
undo flash-flood [ lsp-count ] [ max-timer-interval interval ] [ level-1 | level-2 ] *
| Parameter | Description | Value |
|---|---|---|
| lsp-count | Specifies the maximum number of LSPs to be flooded each time for an interface. |
The value ranges from 1 to 15. By default, it is 5. |
| max-timer-interval interval | Specifies the maximum interval for flooding these LSPs. If the number of LSPs to be flooded exceeds the value of lsp-count, a maximum of lsp-count number of LSPs are flooded each time in time sequence at an interval specified by interval until all the LSPs are flooded. |
The value ranges from 10 to 50000 milliseconds. By default, it is 10 milliseconds. |
| level-1 | Enables LSP fast flooding in Level-1. |
- |
| level-2 | Enables LSP fast flooding in Level-2. NOTE:
If Level-1 or Level-2 is not specified in the command, the LSP fast flooding will enable on both Level-1 and Level-2 areas. |
- |
Usage Scenario
If the link state of an IS-IS device change, the IS-IS device will notify its neighbors by sending LSP packets. When all LSDBs of IS-IS devices on the network are synchronized, the network convergence is complete. By default, LSP flooding is controlled by a timer. Only when the timer expires, new LSPs can be flooded. If you want to speed up the network convergence, run the flash-flood command to enable LSP fast flooding when link states change.
Prerequisites
An IS-IS process has been created and the IS-IS view is displayed by running the isis [ process-id ] [ vpn-instance vpn-instance-name ] command.
Configuration Impact
LSP fast flooding brings the change of LSDBs, and the IS-IS routes will be calculated after LDSBs are synchronized. Therefore, enabling LSP fast flooding may cause frequent route calculation, which consumes system resources and degrade the system performance.