Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!apple!oliveb!pyramid!csg From: csg@pyramid.pyramid.com (Carl S. Gutekunst) Newsgroups: ca.unix,comp.sys.sequent Subject: Re: SLIP (Serial Line Internet Protocol) running on a Sequent or 4.2BSD bas Keywords: SLIP Message-ID: <63935@pyramid.pyramid.com> Date: 25 Mar 89 10:12:59 GMT References: <38990@peregrine.peregrine.com> Distribution: usa Organization: Pyramid Technology Corp., Mountain View, CA Lines: 86 In article <38990@peregrine.peregrine.com> robert@peregrine.peregrine.com (Robert Young) writes: >I am looking for a SLIP package to run on a Sequent machine ( DYNIX 3.0.12). It's out there somewhere. I'd be curious if the versions that have been done for Dynix are symmetrized, or single threaded. The big headache on any of these parallel UNIX systems is symmetrizing the stock drivers, and it's often easier to just not bother. (The original Lachman NFS port was single threaded, for example.) Of course, for the vendor to actually *ship* a product, it has to be symmetrized; that's one reason this kind of thing takes longer coming from the vendor than it does to pluck it off the net. > a) NCD-16 Terminals > b) A workstaion running an X-Windows Server (PCXVIEW for example) > c) SLIP Apples and oranges. You have at least three issues floating here: X Server terminal vs. Workstation with X server software and: Ethernet vs. SLIP and: PC Word Processing vs. Host-based Word Processing The terminal vs. workstation issue is pretty blurry; an NCD is a much faster piece of iron than a PC running an X Server, for example, but less versatile. (Personally I'd take the NCD; for the money you get a much better display.) And of course the original X server is a Sun Workstation. But you might not want X at all; I know a lot of people who are happy with Microsoft Windows and PC/NFS. SLIP vs. Ethernet is a little more clear-cut, but hardly obvious. Most of the X Servers I've seen -- either plug-and-go terminals or software packages -- will talk either one. SLIP is lots cheaper; you only need an RS-232 line. But it has some serious problems: - SLIP is slower in the first place. Unless Sequent has replaced the Systech mux boards, you are pretty much limited to 9600 baud; with TCP/IP overhead, it will be visably slower than a direct 9600 baud tty line. You won't care for text; you *will* care for graphics or WYSIWYG word processors. - The 4.2BSD networking code in Dynix -- and the 4.3BSD code, too -- is tuned for very fast networks. We (Pyramid) have been running SLIP over various interfaces for a while now, and have tried a large collection of different X Servers over SLIP, at speeds from 4800 baud to 38.4K. The results were equivocal at best. Timeouts and TCP retransmissions occur at awkwards times, causing ugly delays as the protocol trips over itself. And it varied from terminal to terminal; some worked better at slower speeds, others at higher. The solution is Van Jacobson's intelligent timeout enhancements that were added to the 4.3BSD-tahoe release. I've talked to people who have seen this at work on a Sun, and it provides much smoother -- though not ideal -- X Server operation. But as far as I know, the only vendor shipping this today is Sun. And ironically, Sun doesn't support SLIP. - One of the biggest wins of X Server on Ethernet is that you aren't tied to a single host. If you're main machine dies, no sweat; log into another, and keep going on something else. With SLIP, you are as tied to the host as if you were on a direct RS-232 link -- because, in fact, you are. - With Ethernet, you need to only run one length of cable. With SLIP, you have to run individual RS-232 lines everywhere, just like for terminals. On the whole, I'm not very happy with low-speed SLIP as a network solution *today*. In the near future, that will change dramatically; SLIP is rapidly becoming a very important link-level protocol (to its creator's considerable surprise and amusement). >Is it better to just use an XWINDOWS terminal and run the Word Processor >right out of the Sequent? As opposed to what? It sounds to me like you haven't really thought through what you are trying to do here. I can run PageMaker on a PC using PC/NFS to link into the host system, running over Ethernet or SLIP. In that case, all the computation is done on the PC, but the storage is on the host. PC/NFS takes care of the remote login that way, too. Or I can run FrameMaker on my host, using an X Server terminal or a PC with X Server software; all the computation is done on the host, and the terminal (or PC) just handles the graphics primitives. Which to chose depends on far more factors than we can go into here. The X Server is going to be faster, in all probability. A PC allows you to do work locally. An X terminal like the NCD gives a much more reabable display for the money. If you are already doing all your other work on the big host, then it would be silly to split your work off onto a PC. And so on.