Configuring IS-IS NSR
After an active/standby switchover, the GR restarter obtains routing information from its neighbors, and the IS-IS process must learn all the routes. If the network topology changes during the switchover, removed routes cannot be updated to the device, which can result in blackhole routes.
NSR solves the problem by backing up IS-IS link state information from the active process to the standby process. After an active/standby switchover, NSR can complete link state recovery and route regeneration without requiring the cooperation of other devices.
![[IMPORTANT: ]](images/important.png) | IMPORTANT: IS-IS NSR and IS-IS GR are mutually exclusive. Do not configure them at the same time. | |
To configure IS-IS NSR:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter IS-IS view. | isis [ process-id ] [ vpn-instance vpn-instance-name ] | N/A |
3. Enable IS-IS NSR. | non-stop-routing | By default, IS-IS NSR is disabled. IS-IS NSR takes effect on a per-process basis. As a best practice, enable NSR for each IS-IS process. |