Cisco ISR 4321 upgrade from16.6.4 to 17.12.4

[stefanmtomasevic]

First:

is this one hop upgrade?

and second:

Do I need to upgrade rommon first (to16.12 (2r)) and then firmware to 17.12.4 or I can upgrade it directly without rommon upgrading?

Thank you.

[Flavio Miranda]

@stefanmtomasevic 

You can find this information here

https://www.cisco.com/c/en/us/td/docs/routers/access/isr4400/software/configuration/xe-17/isr4400-sw-config-xe-17/install.html

 Related to the ROMMON:

From Cisco IOS XE Release 17.6.1 onwards, the ROMMON image will not be released as a standalone package, and will be packaged with the IOS XE image. 17.6.1 ROMMON will only be used in devices with manufacturing date equal or later than 2535. You can view your device manufacturing date with the CLI command show license udi . For example, elixir_p1b_11#show license udi UDI: PID:C1131X-8PWB, SN: FGL2451L5MJ The device manufacturing date in this example is 2451.

Related to the upgrade path, no restriction is mentioned on the release notes

https://www.cisco.com/c/en/us/td/docs/routers/access/4400/release/xe-17-12/isr4k-rel-notes-xe-17-12.html#con_180601

[stefanmtomasevic]

for rommon:

mine is 2312, so if I understand correctly, it is before 2535?

Does this mean that I only need 17.12.4 firmware, and no additional softeware i on order to upgrade ISR 4321

[Flavio Miranda]

That´s what I understand too. 

[Leo Laohoo]

Please do not perform a direct upgrade, from 16.X.X, to 17.12.4 because the router may go into a crash loop.  

Update the ROMMON to 16.12.2r first, upgrade to 17.9.4/17.9.5 and then go to 17.12.4.

Cisco ISR & ASR 1k Routers: IOS-XE/Firmware Upgrade (Install Mode)