Two protocols support connection to the Internet via modem: SLIP (Serial Line Internet
Protocol) and PPP (Point to Point Protocol). As the name suggests, SLIP supports only
IP. It is an older, less rugged protocol. Its only advantage is that it may be available
where PPP isn’t. If you have the choice, always take PPP: it differs from SLIP in being
able to handle multiple protocols simultaneously, and it’s also used on many DSL links
(PPP over Ethernet or PPPoE). In this chapter, we’ll look only at PPP....