| Phase three connects the ATM core |
| switch directly to LAN switches in the |
| wiring closet and to centralized or |
| distributed ATM routers. The network |
| backbone is now ATM-centric, with all |
| other devices at the periphery. Multilayer |
| switches have the intelligence to forward |
| packets between the different VLANs |
| locally, or layer 2 switches, or a |
| combination of both. |
| Phase four is the end-to-end switching |
| with integral VLAN and multilayer |
| switching capability. Route and Switch |
| Processors are distributed over the |
| ATM fabric. |