Local to Wide Area Connections: Access Networks
The link from a LAN, or a collection of linked LANs, to a wide area network is usually accomplished by some variation on telephone company technology. There are two general categories of access networks: carriers and services. We'll talk first about the carriers, which just provide the physical links that create a path from place to place. Other than (in some cases) putting the data into frames, there are no addressing or other software components provided; we could call this U-Switch. Second, we'll review the complete network services that the telcos and their competitors provide. For consistency, think of the carriers as Layer 1 and the services as Layer 2.
Carriers (Physical Links)
There are ...