F5 with out default gateway

Hi ,

 

I am confused with an implementation which i recently came across .

 

its dual arm mode VLAN1 ->10.10.10.x ( VIP) and VLAN 2 ->192.168.100.x ( Servers) . Floating IPs 10.10.10.11 and 192.168.100.1 . servers are having default gateway as 192.168.100.1 . simple straight forward setup .

 

snat auto is used on the virtual servers . and hence source address seen on the servers are 192.168.100.x ( SelfIP non floating of Server VLAN) .

 

there is no routing configured on the box ( no default gateway).

 

when a client access from internet following happens

 

1) ASA does natting 2) traffic reached F5 ( Src: Pub IP , Dst : VIP) 3) F5 send the traffic to the server ( Src: SelfIP , Dst : real IP of server)

 

return back traffic

 

1) Server send the response to the Self IP ( due to snat) 2) traffic reaches F5

 

here is where my question is , with out a default gateway how F5 sends back the traffic to the ASA ? . how F5 knows where to send the public IPs which is coming through ASA interface ?

 

i am literally confused. this is working perfectly fine too

 

when i checked tmsh sh system connection it is showing the public address requesting reaching the F5 . So with out gateway how F5 knows it should send back to the ASA interface?

 

can any one clarify my doubt please ,

 

thanks, PMD