Code upgrade from 11.6 to 12.1.1 HF1

Check this article that summarize in 7 steps what you need to do before upgrading:

https://devcentral.f5.com/codeshare/7-steps-checklist-before-upgrading-your-big-ip-1053

For the upgrade process follow these steps:

1- If you are in Active/Standby cluster mode, start with the Standby Unit. Click on the "Boot Location" that has the newer version from "System ›› Software Management : Boot Locations" for example HD1.2

2- From "System ›› Software Management : Boot Locations ›› HD1.2" for the "Install Configuration" choose "Yes" and verify the "Source Volume" from which the system will copy the config to the destination boot location HD1.2. Normally it will automatically copy the configuration from the running Boot Location to the selected boot location (example from HD1.1 to HD1.2)

3- After that, click on "Activate" to start the upgrade process. For an appliance it takes around 15 to 20 min. For a Virtual appliance it takes less (5 to 10 min).

4- Once the upgrade is finished, you will be prompted to login... Validate that all your VSs are running and they have the same state as the "Active" unit. You can compare the network map to get a quick view on the system "Local Traffic ›› Network Map". If it is identical you can force the failover and apply your test plan to validate that critical services (VSs) are responding same as before the upgrade...

5- Only upgrade the active unit after the standby upgrade is satisfactory.

Hope it helps

Regards