Merging two different LTMs in a HA Pair - Q's

Yes. I've done this twice in the past and am currently involved in a project that is collapsing 3 pairs of 6400's onto a pair of 8950S's.

I did it with Merge Files. I put out a Tech Tip on how to use them a few years ago for Bigpipe. If you are running on v11, then you can still do it...I just haven't written up anything on the How-To's.

This is for v9 and v10. https://devcentral.f5.com/articles/big-ip-and-merge-file-configuration-changes.UmCfcPnksmM

If you want to try it on v11 look into these commands:

tmsh load /sys config merge and tmsh load /sys config merge verify

The just of it is to take out all of the Subnet Ownership, VLAN's, Floating IP's, etc. and pack them into one or more Merge Files. Then shutdown the old device and merge in the VLAN's, Subnet's, Floating-IP's etc. in the right order following by your Monitors, Pools, iRules, and Virtual Servers.

NOTE: If you are thinking about trying to use this ability then I cannot stress enough that you practice it enough times to become good at it. I have actually met people that attempted to use it and didn't really know how....and had disastrous results.

Use it right and you will love it.

Hope this helps.