# Upgrading Systems That Are Operating with Two SRP Modules

Use this procedure when the system contains two SRP modules and is already operating with an earlier software release. Each SRP module keeps the system operational while you upgrade the software on the other, so that you can minimize service interruption.

| Caution: You must upgrade the software on the redundant SRP module when you upgrade the software on the primary SRP module. This action prevents the redundant SRP module from overwriting the new software on the primary SRP module if the primary SRP module fails and the redundant SRP module takes control.

To upgrade the software on a system that is operational and contains two SRP modules:

1. Turn off autosynchronization.
   host1(config)#disable-autosync
2. Copy the new release of the software to NVS of the primary SRP module. Be sure to specify the correct software release (.rel) filename for the router you are using, as described in Identifying the Software Release File.
   - If a firewall separates the router from the network host, transfer files to the user space with the FTP client on the network host, and install files on the system space (See Installing Software When a Firewall Exists.) For example:
     host1#copy /incoming/releases/erx_x-y-z.rel erx_x-y-z.rel
   - If no firewall separates the router from the network host, copy the files to the router (See Installing Software When a Firewall Does Not Exist .) For example:
     host1#copy hostname:/cdrom/x-y-z/erx_x-y-z.rel erx_x-y-z.rel
   - If you are transferring the files from one router to another, copy the file to the system space of the second router from the user space of the first router (See Copying Release Files from One Router to Another.) For example:
     host1#copy boston:/outgoing/releases/erx_x-y-z.rel erx_x-y-z.rel
3. Save the current configuration. For example:
   host1#copy running-configuration system2.cnf
4. Specify that the router should use the new software release when it reboots. For example:
   host1(config)#boot system erx_x-y-z.rel
5. Synchronize the NVS file system of the redundant module with that of the primary module.
   host1#synchronize

   The redundant SRP module automatically reboots because the software release that it is configured to run differs from the software release it is running.

   | Caution: The secondary SRP module does not run the new software until it reboots. If you issue the srp switch command or the primary SRP module fails before the redundant SRP module reboots, then the secondary SRP module runs with the old release when it takes control.

6. Wait for the redundant SRP module to boot, initialize, and reach the standby state. When the module is in standby state, the REDUNDANT LED is on and the ONLINE LED is off. The State field in the show version display indicates the module is in standby.

   After any type of reboot, the primary and redundant SRP module NVS file systems are unsynchronized again.

7. Synchronize the NVS file system of the redundant module with that of the primary module.
   host1#synchronize
8. Switch from the primary SRP module to the redundant SRP module.
   host1#srp switch

   The redundant SRP module becomes the primary. The former primary SRP module reboots and becomes the redundant.

9. Reenable autosynchronization.
   host1(config)#no disable-autosync