Using the Second Routing Engine to Upgrade to a New Software Version

Problem

You want to upgrade the JUNOS software version on the router incrementally to protect against something going wrong during the upgrade.

Solution

If your M-series or T-series router has two Routing Engines and you have configured Routing Engine redundancy (see Recipe 1.30), place the new software version on the second Routing Engine while keeping the currently running version on the first Routing Engine.

First, log in to RE0 and enter configuration mode:

	{master}
	aviva@router1> configure

Disable Routing Engine redundancy:

	{master} [edit]
	aviva@router1>  
delete chassis redundancy

Save the configuration changes on both Routing Engines:

	{master} [edit]
	aviva@router1> commit synchronize and-quit

Upgrade the JUNOS software version on the backup Routing Engine:

	{master}
	aviva@router1> request routing-engine login other-routing-engine
	aviva@router1-backup> request system software add validate /var/tmp/jinstall-
7.4R1.7-domestic-signed.tgz reboot

When the reboot of the backup Routing Engine begins, you are logged out of this Routing Engine and return to the master Routing Engine. Wait a few minutes for the backup Routing Engine to reboot. Then log back in to RE1 and verify that the software is running properly.

At this point, you can also upgrade the JUNOS software version on the master Routing Engine:

	{master}
	aviva@router1> request system software add validate /var/tmp/jinstall-
7.4R1.7-domestic-signed.tgz reboot

This time, you are logged out of the router. Log back in a few minutes after the reboot and reconfigure redundancy:

{master}
	aviva@router1> configure
	[edit]
	aviva@router1# set chassis redundancy routing-engine 0 master
	aviva@router1# set chassis redundancy routing-engine 1 backup
	aviva@router1# set chassis redundancy routing-engine graceful-switchover enable
	aviva@router1# set chassis redundancy routing-engine 0 master
	aviva@router1# commit synchronize and-quit

Then verify that the router is running properly and that RE0 is again the master.

Discussion

In the upgrade procedure described in Recipe 1.22, you overwrite the existing version of JUNOS software with the newer version. If something goes wrong during the upgrade process or if the image you load is damaged in some way, you might not be able to access the router, so you might not be able to reload the previous working version of the software.

Most M-series or T-series routers have two Routing Engines, and you can take advantage of this when you are upgrading software releases. You can install the new software release on the backup Routing Engine while keeping the currently running version on the master Routing Engine. Then make sure that the new software version is running correctly on the backup Routing Engine before upgrading the software on the master Routing Engine.

See Also

Recipes 1.22 and 1.30