Devices in a chassis cluster can be upgraded separately one at a time; some models allow one device after the other to be upgraded using failover and an in-service software upgrade (ISSU) to reduce the operational impact of the upgrade.

To upgrade each device in a chassis cluster separately:

During this type of chassis cluster upgrade, a service disruption of about 3 to 5 minutes occurs.

1. Load the new image file on node 0.
2. Perform the image upgrade without rebooting the node by entering:
   

   user@host> request system software add image_name

3. Load the new image file on node 1.
4. Repeat Step 2.
5. Reboot both nodes simultaneously.