Date: Tue, 23 Dec 1997 17:29:46 -0500 (EST) From: "T. William Wells" <bill@twwells.com> To: brian@awfulhak.org (Brian Somers) Cc: freebsd-questions@freebsd.org Subject: Re: ppp mtu/mru Message-ID: <E0xkcpe-00077E-00@twwells.com> In-Reply-To: <199712232109.VAA13858@awfulhak.demon.co.uk> from "Brian Somers" at Dec 23, 97 09:09:58 pm
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> I would think that the default max queue size (2248 bytes?) would be > sufficient for good response with a reasonably fast modem - a 33.6k > modem should send 2248 bytes in about .53 of a second. Adding in 140ms for the modem delay and double it, so you can see the results of your actions....1.34 seconds. But that doesn't really account for the delays I see, either -- once you've started a packet, you're committed to that packet, even if the kernel has accepted but a single byte of it. Thus, one can expect to see two second delays on occasion...in fact, it's more than "on occasion" if one's line is busy. Obviously, there's nothing one can do about the packet commitment thing, other than decreasing one's MTU (which I have done). Modem delays can be decreased by turning off compression and error correction (I've done the former but not the latter - my modems wouldn't sync when I tried that and I didn't have the time to play). But that still leaves well over a second of latency for interactive use.
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