halls@boulder.Colorado.EDU (Andy Halls) (02/11/88)
Excuse me, do I unserstand it right. Is Serial Line IP (SLIP) a
protocol that works over serial lines that supports tcp stuff, like
ftp and rlogin ???
Would someone be so kind as to educate me. Also how can I get my hands
on such a thing.
Andy Halls
phone: home (303) 455-9139 work (303) 282-2166
uucp: {cires | hao | nbires}boulder!halls
internet: halls@boulder.colorado.eduJBVB@AI.AI.MIT.EDU ("James B. VanBokkelen") (02/12/88)
SLIP is a primitive encapsulation for IP on serial lines (usually asynchronous). IP using it works the same way as IP using Ethernet, or IP over X.25, or IP over Token Ring. I have been told that SLIP has its roots in an old serial protocol 3Com came up with for communicating between fileservers, and was adopted for use with IP and asynchronous serial lines some time later, initially for use between gateways (IP routers). Rick Adams did a public domain implementation for 4.2 Unix, and now one is distributed with 4.3. It is only relatively recently that SLIP has been supported by any commercial vendors. Commercial implementations that I know of include ours, for the IBM PC, and cisco Systems' SLIP port concentrator/terminal concentrator/IP router. I have heard that Sun will support it soon, if not already, and that Encore has or will have something for their Annex. James B. VanBokkelen FTP Software Inc.
guy@sun.uucp (Guy Harris) (02/12/88)
> I have been told that SLIP has its roots in an old serial protocol 3Com > came up with for communicating between fileservers, and was adopted for > use with IP and asynchronous serial lines some time later, initially for > use between gateways (IP routers). Rick Adams did a public domain > implementation for 4.2 Unix, and now one is distributed with 4.3. The history, as I understand it (the CCI parts are correct - I was there - but I don't know the history of this encapsulation scheme at 3Com): 3Com's UNET TCP/IP implementation had a serial line encapsulation for IP packets. I don't know for what this encapsulation was originally designed, but it was used in UNET for getting two machines with serial port hardware and nothing else to talk IP to each other; it was not just used between gateways. The Naval Surface Weapons Center put out a bid for an office automation system; Computer Consoles, Inc. bid a system consisting of two VAXes running 4.2BSD (with S5 compatibility additions) and lots of CCI Power 5/20 machines running S3 with UNET. There needed to be *some* way to get the 5/20s to talk to the VAXes, so Rick whipped up the original SLIP; it used the 3Com encapsulation so it could talk to the 5/20s running UNET. He subsequently reimplemented it while at the Center for Seismic studies. > I have heard that Sun will support it soon, if not already, We don't have it now; I don't expect it to be officially supported in the next release, but Rick does have a version that can, I believe, be put into current SunOS releases, and I expect there will be versions to put into future releases. It may end up in a future release, but I don't know one way or the other. -- Guy Harris {ihnp4, decvax, seismo, decwrl, ...}!sun!guy guy@sun.com (or guy@sun.arpa)
lamy@ai.toronto.edu (Jean-Francois Lamy) (02/12/88)
On a related note: I'm curious to know how an asynchronous SLIP (is there such a beast?) would fare on high-speed Telebit style modems. Anybody tried such a setup? Jean-Francois Lamy AI Group, Department of Computer Science lamy@ai.toronto.edu University of Toronto, Canada M5S 1A4 uunet!ai.toronto.edu!lamy
merlin@hqda-ai.UUCP (David S. Hayes) (02/12/88)
In article <41751@sun.uucp>, guy@sun.uucp (Guy Harris) writes: > We don't have it now; I don't expect it to be officially supported > in the next release, but Rick does have a version that can, I > believe, be put into current SunOS releases, and I expect there > will be versions to put into future releases. It may end up in a > future release, but I don't know one way or the other. > > Guy Harris {ihnp4, decvax, seismo, decwrl, ...}!sun!guy > guy@sun.com (or guy@sun.arpa) Sun should be adding this. Yes, there is a SLIP that runs on Suns. It was "solarized" by Chris Torek at the University of Maryland. I have tried it, and it does work. The problem is that in a binary-only Sun release, there is no way to support a "disconnect-interface" procedure. This results in a kernel crash if the remote end goes away. With a dedicated hardwire line, that's not too much of a problem, but it can be a real pain when you've got some intervening hardware. Sun should add a full SLIP, including disconnect, immediately. The code is already available from Chris Torek, including the disconnect business. For a company that claims that "The network is the computer," here's an opportunity to put that motto into practice. -- David S. Hayes, The Merlin of Avalon PhoneNet: (202) 694-6900 UUCP: *!uunet!cos!hqda-ai!merlin ARPA: ai01@hios-pent.arpa
chris@GYRE.UMD.EDU (Chris Torek) (02/13/88)
Careful! I only rewrote Rick Adams' code for 4.3BSD, removing the horrible hacks needed to make it work in a binary-only system, where there is no way to attach the interfaces at kernel startup. Mark Weiser re-re-edited the code to run under several different SunOS releases; various versions of this are available via anonymous FTP from host mimsy.umd.edu. At the moment, mimsy is being emulated by a Sun-3/50 with less than 5% of the disk space of the Vax-11/780-5 whose place it is holding, and the FTP archives are unavailable. We anticipate that the machine should be working again by the middle of next week, assuming that nothing major went wrong when it was moved across the campus. Please also restrict anonymous FTP access to 7 AM to 7 PM EST (1200 to 0000 UTC) if possible. Chris
PAP4@AI.AI.MIT.EDU ("Philip A. Prindeville") (02/15/88)
Jean-Francois, This was actually the basis of a BOF (birds of a feather) meeting at the TCP/IP Interoperability Conference last December. The conclusion was (as I remember hearing -- I was not there) it works, but has some hitches: You have to use the right kind of flow-control i.e. your interface must implement RTS/CTS handshaking. Dialing is tricky (I don't remember the details). And the turn-around-time (since it is a pseudo full-duplex modem) makes it undesireable for interactive applications, but works quite nicely with batch data transfers e.g. mail and ftp. -Philip