PPP Connections

So far, you have seen Internet connections based on a local area network (LAN) and a default gateway on that network. However, if you have a modem and telephone line to connect to the Internet, you cannot use the same host-to-network layer interfaces described in previous sections because your connection does not run over the Ethernet physical medium.

The most popular standard for single-machine Internet connectivity with a modem is PPP (Point-to-Point Protocol). Although PPP is a very flexible protocol, its main use is to connect one machine without a direct IP connection to second machine (a PPP server) that has one, with the second machine possibly asking the first for a username and password along the way.

When you dial up and ...

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