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