Using our SonicWALL NSA 3600 and doing some cleanup, I noticed that one our physical interface, the X5, does not have a subinterface for the VLAN 7 (VoIP VLAN). Instead, it has the gateway IP of the subnet (172.16.7.0/24).
There is a trunk connected to this interface (coming from a Dell N4023F, the port setting is a dot1q trunk with PVID 7).
Why is there no subinterface on the SonicWALL? How does it know that the VLAN is tagged as 7, so how does it route it?
Another strange thing is that this interface has a subinterface, but for the VLAN 8 (so it knows how to route the VLAN 8 from the switch). Why not simply adding a subinterface for the VLAN 7? Is it really necessary?
My guess is that the VLAN 7 is only used on the switch, and nowhere else, which does not really make sense, am I correct here?