Failover cable on F5 4000 pair

The failover cable goes into the failover port. It's a dedicated port to interconnect two BIG-IP. Failover cable is not mandatory to setup HA, but can trigger faster failover. So it can be used with a Network Failover configuration. My recommendation is to create a LACP trunk of 2 interfaces on each of your BIG-IPs. Create a HA VLAN untagged to this trunk on both devices Create a Self IP with Port Lockdown Allow Default on the HA VLAN on both devices (in same /30 network or bigger). Use these IP to configure ConfigSync, Network Failover and Network Mirroring if you need mirror SNAT, VS connections and/or persistence records. Salim