F5 LTM creating VLANs etc

For example:

Core A - vlan 5 SVI - 10.10.10.2/24 HA-10.10.10.1 (Gateway)

Core B - vlan 5 SVI - 10.10.10.3/24 HA-10.10.10.1

Ltm A - vlan 5 Self-IP 10.10.10.4/24 Floating-10.10.10.1 (Same gateway as your Core switches)

Ltm B - vlan 5 Self-IP 10.10.10.5/24

By doing this method, your routing table will have 2 default gateway routes for this subnet and the mac table will be on both the LTM and the Core switch. Due to this, you will have a lot of routing issues. (It will break!)

The L2 pass thru methodology would be to not have any self IPs for vlan 5 on the LTMs but yet still use the vlan5 subnet as "backend/Real IP" pool members of your VS. In this way, the routing table to the LTM will not have a 'directly connected' route in its table and go out its global default route. So, if you wanted to utilize vlan5 on your LTM... remove all self IPs, forwarding VS, L4 VS, and Vlans that relate to vlan5 on the LTM. Just make sure there is a global default route that goes back to your core switches. Also, insure that vlan5 is extended down to the LTM trunk if you are utilizing vlan allow list on your core switches.