Vlan behind a single DSL line

Figured there was some smart people in these forums so here it goes…

I was just wondering if its possible to setup a Vlan (2 lan subnets) lets say and and share a common DSL router (1 public IP) with NAT. I found that there is a DSL Modem/Router/Switch all in one unit which has Vlan built in on its four LAN ports, but was wonder if a “layer 3” switch in between the 2 LAN subnets and the DSL router would be able to forward everything through a DSL NAT router to the internet.

One of those things that kinda came up with a client that is gonna be too complicated for their needs, but now I’m just interested in figuring it out for the “fun” of it :rolleyes: