From owner-freebsd-questions Tue Jan 16 12:14:13 1996 Return-Path: owner-questions Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id MAA07743 for questions-outgoing; Tue, 16 Jan 1996 12:14:13 -0800 (PST) Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id MAA07735 for ; Tue, 16 Jan 1996 12:14:09 -0800 (PST) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id VAA11895; Tue, 16 Jan 1996 21:15:03 +0100 From: Luigi Rizzo Message-Id: <199601162015.VAA11895@labinfo.iet.unipi.it> Subject: Re: delays in ppp solved To: wes@intele.net (Barnacle Wes) Date: Tue, 16 Jan 1996 21:15:03 +0100 (MET) Cc: questions@FreeBSD.org In-Reply-To: <199601161717.KAA08693@intele.net> from "Barnacle Wes" at Jan 16, 96 10:17:23 am X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-questions@FreeBSD.org Precedence: bulk > Aha! When I first started with SLIP, then PPP, one of the cardinal > rules given to me by Terry Lambert was "turn off modem compression > completely." Reasons for this edict I've garnered over the years include: > > 3. Modem compression, as you have noticed, often interferes with VJ > compression used in SLIP and PPP implementations. > > 2. Modem compression often interferes with, and lengthens transfer of, > compressed files such as .gz and .jpg. > > 1. Modem compression slows down turn-around time -- terrible for > interactive sessions. I believe that my modem is using compression, and interactive performance is quite good (while am having problems with PPP, not sure about the reason though; since I did not have time to investigate, I do not want to bother people on the list). Interference with already-compressed data shouldn't be too bad, possibly a loss of 10% or so (probably less: the algorithm should continuously check how it is performing, and switch compression on-off based on the results). The only reason I can think modem compression can cause problems is that the compression algorithm of the modem decides that it is worth waiting for more bytes to come, while for some reason PPP times out. Does this make sense ? Luigi ==================================================================== Luigi Rizzo Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it Universita' di Pisa tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 http://www.iet.unipi.it/~luigi/ ====================================================================