Load-Balancing Client/Server on same subnet

"I would say, if one server sees ARP request / response / broadcast from the client 10.1.1.12, the server should learn this entry and so, send traffic back to the client instead of the BIGIP."

That makes sense. Thanks a lot

"I do not understand why working servers don't have any entry for 10.1.1.12 if the original TCP connection uses it."

Yep, that was a head scratcher. I'm wondering if the linux box doesn't need to ARP out for reply traffic since the request has an IP/MAC association in the packet. But it doesn't seem to cache it either. Thanks for replying.

I'll update the thread if I find anything else, but I'm thinking on the one that's not working, it learned the mac through some unknown communication where it needed to ARP out for .12. It didn't work after clearing the entry, possibly due to the linux implementation of the ARP cache, which keeps the entry in the table as "Incomplete" for 20+ seconds. It might be ARPing out during the timeout period.