F5 and its gateway

Hi davidy2001 , 
         F5 do not need to define a gateway to it such as " servers , PCs , ... " , F5 needs only to main objects of configuration to make it alive in network ( Vlan and self ip " normal ip address from this Vlan subnet" ) 
Lets simplify : 
> we have F5 appliance and a Layer 3 Switch in front of. 
We need to connect both of devices with each other. 
I will talk about incomming traffic : 
> Layer 3 Switch : 

- assign a physical interface 

- create VLAN and give it Tag 20 

- give this interface ip from vlan 20 subnet " lets say " 20.20.20.0/24" and Layer 3 switch take 20.20.20.2

> For F5 : 
- Create VLAN and give it TAG 20 as well , assign one of F5 physical interfaces on it 

- Create self IP address from Vlan 20 subnet lets say "20.20.20.3" and put Vlan_Tag 20 in it during its configuration.

after that , both of devices can reach to other , now both of them at the same subnet. 

> you can call the Layer 3 switch IP 20.20.20.2 as the Gateway of F5 it is up to you. 

> After That you create a Virtual server , I know that Virtual server is Confusing you as you see that " Virtual server " is the only speaker with F5 Peer device : 
This Logically or as traffic flow is Correct , But Physically the self IP " 20.20.20.3 " in our example it the only component that maintains the reachability with its peer device. 

> if you do not Put the Peer device and F5 in same Vlan and give them IP address , they can not take. 

> There is no configuration in F5 to create a Gateway of Peer device but Logically you can call it " Layer 3 Switch is Gateway of F5 to go outside the network ". 

> that was my explanation , you can specify your request and I will follow up your requests and try to get solution for you. 

Thank you