on a very high level:
Due to the little information you gave, it is difficult to go into more details. You didn't tell us whether or not you have a cluster, or you want to change / keep the management and self-ip adresses or other network configurations.
A word of caution: If you have never done this before, you should consider to hire a consulting company to assist you.
In addition to what Daniel wrote, it's also possible to add the new i3800 appliances to the existing cluster. Make sure you sync the configuration to the new members. Then failover to one of the new units and remove the i2600 appliances from the cluster. When using this approach it's also key to use the same BIG-IP version, but you don't need to worry about the masterkeys.
Great peace of advice Daniel and Niels. Thank you so much. My existing environment has an active/standby cluster. So if I go by Niels way, I just need to add the new i3800 to the cluster and sync the configuration then do the failover. I was just not sure if an i3800 could be added to a cluster having i2800 members.
Regarding the retention of management and self IP(s), I haven't been communicated from the applications team whether they need a new set IP or want to have the existing. So if they want the same set of IP, Daniel what extra steps will be needed ?
the way the Niels suggested is also very promising, with the one exception when you are using APM.
In case you are not using APM, it is really a good way and I'd recommend it too.
The extra steps for the other process of migration depend a bit on the way you want to migrate.
Do you plan to have a zero downtime migration, or do you have a change window?
Independent from that, I will try to give some general advice.
In case you want to keep the management and self IP addresses, you could restore the UCS archive on the new platform using options no-license and no-platform-check (K14906).
If you want to change the management IP and also the self IPs you could use no-license and platform-migrate options (K82540512).
However, changing management or self IP addresses usually is also not a big issue, unless they are used for config sync, HA or mirroring. In that case... we are back to the point where I would recommend to get help from someone who has done this before.
Either way - you would have to make a plan how the old and new devices are not online at the same time, to avoid IP address conflicts. Easiest is, in my opinion, to disable the interfaces on the switch at a certain point in time.
Hi Daniel, Thank you again. We will have change window for this. And we don't have APM, it's just LTM. Unfortunately we are the vendor for this implementation for our client. We do have an operations team for F5 but no production expertise on platform migrations. Now I have to set up a call and discuss the critical points that you and Neils have put forth. I'll get back to this with outcomes and if I need more assist. Thank you.