What is the difference between SLIP and PPP?
SLIP is called Serial Line Internet Protocol and PPP is the
acronym of Point-to-Point Protocol.
PPP has some additional benefits. Unlike SLIP (which can only
transport TCP/IP traffic), PPP is a multi-protocol transport
mechanism. This means that PPP not only transports TCP/IP traffic,
but can also transport IPX and Appletalk traffic, to name just a
few. Better yet, PPP lets you transport all of these protocols at
the same time - on the same connection.
This is often not a concern for most users since their purpose
of either using SLIP or PPP is to connect to the internet and the
internet uses TCP/IP only. Therefore, there is no need to transport
With SLIP, you have to know the IP address assigned to you by your
service provider. You also need to know the IP address of the
remote system you will be dialing into. If IP addresses are
dynamically assigned (depends on your service provider), your SLIP
software needs to be able to pick up the IP assignments
automatically failing which you have to setup them up manually. You
may also need to configure such details as MTU (maximum
transmission unit), MRU (maximum receive unit), use of VJ
compression header (ie., CSLIP), etc. All these can get confusing
PPP addresses this problem by negotiating configuration
parameters at the start of the connection. This can greatly
simplify the configuration of your PPP connection.
Most SLIP/PPP software can dial-up and automatically login for you.
However, they often depend on your service provider's system
sending out standard prompts (eg, "login:" to get the login name
and "password:" to get the password). If they are any way
non-standard, you either need to write a script to automate the
login process yourself or login manually in the terminal emulation
mode of your SLIP/PPP software.
PPP provides two methods with which logins can be automated -
PAP (Password Authentication Protocol) and CHAP
(Challenge-Handshake Authentication Protocol). Both provide the
means for your system to automatically send your login
userid/password information to the remote system.