@johnpoz said in 2 Newbie Questions on Network Architecture:
So when you do vlan X to Y on the same physical interface you have actually cut your bandwidth in half when devices on these different vlans are talking to each other.
It's not quite that simple. While both VLANs are on the same wire, the portion of bandwidth will depend on the traffic patterns. For example, with a large file transfer, most of the bandwidth will be used in one direction, with only a small amount in the other. Bear in mind, with full duplex, what happens in one direction does not affect the other, so when doing that file transfer, one VLAN will have most of it's traffic in one direction and the other VLAN, in the other direction.