Router to Switch encapsulation - What is this called?

redgunner

Hey,

I have a router and a switch - I have created a VLAN and I have allowed the switch to access that VLAN successfully.

I have G0/0 which I have gave 1.1.1.1/30 and I created G0/0.1 which I gave 192.168.1.1/24

So my two questions are as follows:

G0/0.1 When I add a dot after an interface and I tell it to use encapsulation dot1q what does the . do? Is it a virtual interface? whats the correct term for this.
G0/0 - Does this interface have to have an IP address for the subsequent "virtual interfaces" to work or can I ignore this but still provide an ip address?

Thanks in advance for your help!

iproute.se

redgunner wrote: »

Hey,
G0/0.1 When I add a dot after an interface and I tell it to use encapsulation dot1q what does the . do? Is it a virtual interface? whats the correct term for this.

It's a subinterface of Gi0/0

redgunner wrote: »

G0/0 - Does this interface have to have an IP address for the subsequent "virtual interfaces" to work or can I ignore this but still provide an ip address?

The master interface does not need to have an ip address, only the subinterface(s) need to.

OfWolfAndMan

You do not need to have an IP address on the physical interface. You can have it exclusively on just sub interfaces. In fact, you could do G0/1.1 and assign it to vlan 12 if you wanted to, but obviously matching those two values is best practice.

Also, don't forget to enable the physical interface, not just the sub interface. Otherwise you won't get a physical connection (Seen people miss it before).

redgunner

So if my physical interface had no IP was but turned on then my subsequent subinterfaces would still work as intended, but if my physical interface was turned off then my subinterfaces just couldn't function?

DCD

Correct.