In this part, we examine the technologies that enable the metro networking environment. We divide these into five categories and will examine each in turn: premises, access, transport, switching, and interfaces.

Premises technologies are those used by the customer for intracorporate communications such as local area networks (LANs, most notably Ethernet). In the metro networking arena, premises technologies play an important role because they generate and terminate the content that ultimately drives the demand for bandwidth at the edge of the network. Today the single biggest driver at the premises level is Ethernet. Described briefly in an earlier part of the book, Ethernet has cast off its LAN limitations and is now running freely about the network, performing all sorts of tasks for which it was never intended yet doing them exceptionally well. It has been so successful as a point-to-point transport scheme that a new type of carrier has emerged, offering carrier-class Ethernet for long-haul and metro applications. We begin our discussion, then, with Ethernet.