High Availability Configuration

Suresh, in order to minimise the changes you need to make on the devices 'surrounding' the F5, you'll probably want to change the single device's 'real' IPs to floating and use new IPs for the reals. This should prevent you having to modifying routes elsewhere (if relevant).

A few more tips based on my recent experience;

-Configure every HA related feature you possibly can (particularly floating IPs and MAC Masquerade addresses) BEFORE you create the device trust. It's probably also a good idea to restart all services on each device first too.

-Expect downtime - I'd suggest at least an hour or two, plus backout time.

-Test the failover and the operation of each feature you expect to trigger it.

-Ensure you're testing also includes a reboot of the primary and then the secondary device. This should help you understand what will happen if either is reset for any reason in the future and will give you confidence (if all is well) that the behaviour you expect when an entire device fails is what you'll actually get.

-Have a backout plan, backup pre-change configurations etc. etc.

I'd be interested to know how it goes. Cheers