How the IP Router Works

Overview

An IP network is configured on each interface where IP packets are received and sent. The interface can be either a local LAN interface or a serial line interface for a wide area network. This paper shows a wide area router (Router 1) connecting two local Ethernet networks (Santa Clara buildings 1 and 2) to two wide area networks (Los Angeles and Santa Barbara). The Los Angeles network is connected by a point-to-point line, and the Santa Barbara network is connected by an X.25 link. Although we show that the wide area ports that connect the Santa Clara network to the Los Angeles network are assigned IP addresses, PPP does not require that you assign an IP address to each wide area port. If you do not want to assign an IP address to a wide area port, you must set the SETDefault -IP NETaddr command to UnNumbered.