But on a L2 switch, must every VLAN have a unique subnet ? If so, how is this "enforced"? Does the IOS software or switch firmware limit this. Or is it as simple as at L3 devices on different subnets cannot communicate even if these devices are on th...

It will also be interesting to see how the move to a hosted environment for email, such as the recent reports about the GSA moving to Google, will affect this space. Certainly it ties in with the notion of the need for mobility. We may indeed be reac...