Dumb(I think) question about VLAN routing.

[cisco]

OK, I don't know if it's the covid stay at home has my brain fried or I'm just overthinking this.

I have a main distro switch with about 30 VLAN's on it and it is the gateway for most of them. i.e. each VLAN has an interface IP assigned in this switch.

I also have a switch connected to that distro switch in our server room to give my VM's in there connection to the access-layer network VLAN's.

There is a single 1gig fiber between these two.

Am I right in thinking that even if two VM's on different VLAN's connected to that one switch in the server room NEED to transfer traffic between them, the traffic still must travel over the 1Gig link to the distro switch to route between the VLAN interfaces?

Or, are the switches doing a MAC connection and realizing both source and destination VLANS are on the same switch in the server room and just connecting them there?

Sorry if this is a ridiculous question, I feel like I should already know the answer but don't.

Thanks,

Chuck

[UncleJP · Accepted solution]

Hi there!

In order to do inter-VLAN communication, there needs to be a routed interface involved. If the switch connected to your distro switch doesn't have any layer 3 routed interfaces, it would need to send its traffic to the distro switch to perform the routing. If the VMs were in the same VLAN, the traffic would remain in the switch they are connected to.

Hope that helps!

Jason

P.S 

There's no such thing as a dumb question.