Hard-wired Failover 4000 series and 8900 series

Hi Claudio,

For hardware failover, the systems must be running the same hardware: http://support.f5.com/kb/en-us/solutions/public/8000/600/sol8665.html?sr=35248250

Starting from v11.4.x, the software failover can be configured between heterogenous devices: http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/tmos-implementations-11-5-0/6.html?sr=35248250

Those 2 devices you're mentioning don't have the same hardware architecture, capabilities, etc. So assuming you'd be able to hack this, and you have all your connections going to the 8900, if it fails and all traffic moves the 4000 series, it's a different number of TMMs, different architecture processing your traffic, which may very well break. I would strongly advise against this and I don't think it's an F5 supported config.

Cheers!