Autor: Krzysztof Wroblewski (chris_at_highresnmr.biophys.upenn.edu)
Data: Fri 29 Apr 1994 - 17:48:48 MET DST
>Co to jest SLIP ??
Taka informacja na ten temat jest dostepna na naszym uniwersytecie:
How to Connect to PennNet by Modem
PennNet Services Center 04/92
psc_at_dccs.upenn.edu (215) 898-8171
How to connect to PennNet by Modem
If you have a computer at home, you already have the most expensive
component you need to dial in to PennNet, the University network. Via
PennNet you can access Library services such as Franklin, the online
catalog, or PennData, the collection of CD-ROM databases; your e-mail
account; documents posted on PennInfo, the campus-wide information
system; and other services and computers on the academic/research
network known as the Internet. Follow the instructions below to set up
the necessary hardware and software to communicate with remote computers
SLIP - Dial-up access to the Internet
(Penn Printout, Volume 9, Number 3, November 1992, Page 8
SLIP: Dial-up access to the Internet
By Randall Couch)
If your lab or office computer is connected to PennNet's IP network
(either through a direct ethernet connection or a gateway box), you may
already be familiar with--and spoiled by--the power and convenience of
client/server computing. Perhaps you
* Initiate high-speed file transfers using FTP clients, such as Fetch
or FTP Software
* Log in directly from your computer to remote Internet hosts using
the Telnet protocol
* Log in to IBM hosts using tn3270 for full-screen IBM terminal emulation
* Access the network news system directly from your computer
* Manage your e-mail from your own computer using a POP client such
as Eudora
* Use the point-and-click Macintosh client for PennInfo
* Work in a windowing environment that allows you to run several of
these programs at once
If you are accustomed to any of these capabilities, connecting to
PennNet from a home computer can be a real step backward. Wouldn't it
be great if you could use IP services from home?
Well, soon you can. Data Communications and Computing Services
(DCCS) has completed the necessary work for PennNet to support SLIP, a
service that makes IP services available over modems and phone lines.
(For a description of PennNet's IP network, see "Visualizing PennNet,"
Penn Printout, October 1990.)
What SLIP does:
---------------
SLIP stands for Serial Line Internet Protocol. SLIP is a
convention for "framing" IP packets, or bundles of data, so that they
can be transmitted over a serial line (such as a cable, or a pair of
modems and a telephone circuit). This allows a home machine to dial up
and become a part of the Internet. In effect, SLIP turns your
computer's serial port into a logical ethernet port. Software that
communicates with the outside world via your lab or office computer's
direct IP connection will function the same way over SLIP, although
somewhat more slowly due to the lower data speed of modem connections.
Remember that make use of the vendor-independent
standard TCP/IP protocol suite. SLIP alone will not allow you to
participate directly in proprietary networks, such as AppleTalk or
Novell Netware, from home.
SLIP employs a client module that runs on your desktop computer,
and a server module that runs on the terminal servers connecting the
dial-in modem pool to PennNet's IP network. The server module is now in
place and ready to accept SLIP traffic. In order to make use of SLIP,
you need a client module for your computer and a suitable high-speed
modem or PennNet Residential data-over-voice service.
SLIP clients:
------------
SLIP clients are available for many computer types, but not all
SLIP clients work correctly with PennNet hardware. Through its
Technology Release process, DCCS has qualified two SLIP clients:
MacSLIP, from Hyde Park Software, for Macintoshes, and FTP Software's
PC/TCP version 2.1 for IBM PC/compatibles. Technology Release documents
describing specific requirements, installation, configuration, and
scripting for these clients are available in the PennNet section of
PennInfo.
A Penn site license is currently being negotiated for MacSLIP. In
the meantime, software and information are available from the
manufacturer, Hyde Park Software, 4003 Avenue H, Austin, TX 78751
(512/454-1170). FTP Software's PC/TCP includes basic IP functions, such as
Telnet
and FTP, in addition to SLIP support. With Penn's discount it costs
$245 for a single user plus $65 for each additional user. For more
information, contact PennNet Services Center at 898-8171 or psc_at_dccs.
Proper setup and use of SLIP software requires some technical
understanding. Newcomers to networking may wish to consult the network
administrators in their Schools and centers. DCCS Engineering will
provide best-effort support via electronic mail for qualified SLIP
clients.
Modem requirements
------------------
As mentioned earlier, SLIP provides access to feature-rich IP
applications at the cost of slower performance than direct IP
connections provide. How much slower? That depends on the capabilities
of the modems at both ends of the phone line. PennNet's dial-in modem
pool (annex: prompt) now supports hardware flow control and speeds up to
14,400 bps without data compression. It also supports error correction
(V.42) and data compression (V.42bis) protocols yielding maximum speeds
up to 38,400 bits per second (bps).
How fast does your modem have to be to make SLIP worth using? That
is a matter of individual judgement. Experienced SLIP users often
recommend a minimum modem speed of 9600 bps to maintain reasonable
response time. Higher-speed modems are suggested for network
applications that involve many images, such as X-Windows-based graphics
applications.
Notwithstanding vendor claims, the technology for 9600-bps and
faster modems is still rapidly evolving. Implementation of relevant
standards by different makers is not entirely consistent. DCCS has
evaluated many low-cost ($400 or less) high-speed modems. All have
strengths and weaknesses, including some that may limit their successful
use with PennNet's dial-in pool. If you are ready to purchase now,
consult the Modem Reports folder in the PennNet section of PennInfo for
DCCS test reports. DCCS continues to track this technology and will
make an announcement as soon as it can qualify a modem without
reservation. Users of PennNet Residential data-over-voice service enjoy dial-up
access to PennNet at 19,200 bps. These connections are ready for SLIP
access, but users still need a SLIP client module such as those
mentioned earlier.
To archiwum zostało wygenerowane przez hypermail 2.1.7 : Wed 19 May 2004 - 15:45:11 MET DST