I have a question regarding a hierarchical design of a campus network.
Take a look at this image:
If I understand correctly the links between each Area Border Router and BBone router are point-to-point Layer 3 connections. With every point-to-point link in it's own subnet (probably a /30).
But I was wondering if, for example, links going from ABR-1 & ABR-2 to BB-R1 go to a switch, would this break the "L3 down to the access level" design idea? If so, why's that?
It would look like: Switch now drawn- The green lines represent one subnet, and the red one a different subnet.
Thanks for your help!