Junos upgrade path and rollback

‎02-21-2020 03:17 AM

Hi There,


I am in the process to upgrade an mx960.

Upgrade path:
Start sw version installed: JUNOS 16.1R5-7
Intermediate sw version: JUNOS 18.1R2-6
Final sw version: JUNOS 18.4R3


Question: what about rollback/downgrade?

I am preparing the following strategy:

Start from: JUNOS 16.1R5-7

1)take snapshot: request system snapshot

2)Prepare recovery bootdevice for version JUNOS 18.1R2-6

3)Save on my usb the juniper.conf.gz


Upgrade: from JUNOS 16.1R5-7 to JUNOS 18.1R2-6

In case of problem when i install the JUNOS 18.1R2-6, is enough to run the command "request system reboot partition alternate" to have the router back to his original OS+Config


Upgrade: from JUNOS 18.1R2-6 to JUNOS 18.4R3

Create and emergency boot device (jinstall-media for 18.1R2-6) + config saved on my usb

In case of problem i will:

- Use the emergency boot device to bring the OS back to 18.1R2-6

- Use the config file to manually load it


Question: do you have any better idea to cover the part with regard problem?

Is the usage of request system reboot partition alternate correct? I read this:

"When the correct snapshot command is issued, the /root file system is backed up to /altroot, and /config is backed up to /altconfig. The /root and /config file systems are on the devices’s CompactFlash card, and the /altroot and /altconfig file systems are on the devices’s hard disk or or solid-state drive (SSD)."

so I am assuming that the sw upgrade is never modify/deleting the content of devices’s hard disk or or solid-state drive (SSD) where /altroot and /altconfig are saved.




Accepted by topic author FabNewCert
‎03-30-2020 05:24 AM

Re: Junos upgrade path and rollback

‎02-24-2020 04:53 PM

You can upgrade directly to 18.4 and that is the prefered target as in general you would try to keep devices on the final EEOL version of the Junos chain.


For rollback snapshots on MX devices I prefer running them to USB drives.  These can then be an actual boot device in the worst case and will include the current configuration and everything.  Run the snapshot command with the target of USB.  Then remove the drive and perform the upgrade from there.


Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)

Re: Junos upgrade path and rollback

‎03-30-2020 05:24 AM

Reading EEOL https://support.juniper.net/support/eol/software/junos/ is not really easy and sometime misleading. 

Yeah looks to me that is possible a direct upgrade i agree.