If the availability of the products needed to implement Alternative C becomes more distant, this alternative may provide some necessary solutions. Central routing is only for outside or inter-campus connections. Ethernet or fast ethernet switches deployed in all buildings reduce the size of the collision domain and provide a scalable building interconnection. This alternative allows the campus to migrate more slowly to ATM for inter-building connections. Routing switches at the core start to distribute routing load.
Some routers stay on old FDDI backbone providing connections for some buildings.
Some direct ATM connections to core permitted as routing switches begin to migrate to buildings. Some buildings are connected to the backbone directly via ATM and have edge routers installed. Ethernet or fast ethernet switches deployed in all buildings reduce the size of the collision domain and provide a scalable building interconnection.