Date: Wed, 20 Mar 1996 19:47:58 -0800 (PST) From: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com> To: jgreco@brasil.moneng.mei.com (Joe Greco) Cc: nate@sri.MT.net, freebsd-isp@freefall.freebsd.org Subject: Re: Microsoft "Get ISDN"? Message-ID: <199603210347.TAA23201@GndRsh.aac.dev.com> In-Reply-To: <199603201819.MAA29896@brasil.moneng.mei.com> from "Joe Greco" at Mar 20, 96 12:19:40 pm
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> > > > I am curious, why do you use SLIP for your dedicated connections? > > > > I don't speak for Joe, but I use SLIP (w/VJ compression) whenever > > possible since it uses less overhead and I seem to have lower latency > > and higher throughput than using both user-mode and kernel-mode PPP on > > FreeBSD boxes. > > I don't have anything to say about higher throughput since in my experience > it's only a mild difference, but the latency issue is mainly due to ppp's > default 1500 mtu. Lowering that (I know one fella who uses 296) will help > latency issues quite a bit. With 1500, you only get two or three packets > per second through the link if somebody is running a large transfer of some > sort. > > Most sites which run dedicated connections will have multiple people using > the link simultaneously, so the lower mtu gives the impression of faster > response. This hurts overall throughput mildly, buuuuut there's always a > tradeoff to be made. > > fyi: SLIP uses a 552 mtu. FYI: SLIP and PPP can use what ever MTU you decided to set them up for, I use 296 mtu on any connection that has interactive trafic on it, and crank it out to 1500 on connections that are computers talking to computers only. This is not a ppp vs slip issue, both can be changed (ppp is much easier to change infact since only one end, the end you control, has to be changed, slip requires that both ends agree on what the mtu is by ifconfig options. I agree with Joe in the use of SLIP for dedicated connections, it just seems easier to me to get them up and working (but then, probably much like Joe, I have been doing slip connections far longer than I have been doing ppp connections and my experience is far deeper). I also have not had to deal with the flakeness there has been over the last year or so in ppp implementations, slip is old, but tried and true technology that does IP very well over a serial line. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD
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