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Newsgroups: comp.os.386bsd.questions Path: sserve!newshost.anu.edu.au!munnari.oz.au!bunyip.cc.uq.oz.au!harbinger.cc.monash.edu.au!yeshua.marcam.com!news.kei.com!sol.ctr.columbia.edu!math.ohio-state.edu!jussieu.fr!univ-lyon1.fr!ensta!itesec!frmug.fr.net!fasterix.frmug.fr.net!pb From: pb@fasterix.frmug.fr.net (Pierre Beyssac) Subject: Re: NetBSD - routing and slip References: <2gv4lc$l0i@darkstar.UCSC.EDU> <1994Jan12.142552.6187@jupiter.sun.csd.unb.ca> <CJJ0w6.ADo@usenet.ucs.indiana.edu> <2h1nm9$147@homer.cs.mcgill.ca> Organization: considered harmful Date: Sat, 15 Jan 1994 00:08:33 GMT Message-ID: <1994Jan15.000833.7419@fasterix.frmug.fr.net> Lines: 38 In article <2h1nm9$147@homer.cs.mcgill.ca>, Marc WANDSCHNEIDER <storm@cs.mcgill.ca> wrote: > it's not. you can't compress a gzip file much more than maybe > a couple of percent, and i think that v42bis isn't willing to spend > that much time finding out. I don't think V42bis would ever be able to compress a gziped file, even by a few percent. I have read in the comp.compression FAQ that V42bis is more or less the "compress" algorithm, which is as you all know less efficient than gzip. With V42bis compression enabled, the most efficient is probably to transfer already gziped files because V42bis stops trying to compress when it does not manage to. > thus, the max transfer rate is about 1400-1500cps on a 14,4 modem > with gzip'd binaries. On a V32bis/V42bis modem (14400 bps with compression enabled), serial port speed set at 57600bps, I get about 1700cps with Taylor UUCP on gziped news batches, and around 1.2Kbps by ftp on SLIP on gziped files. The 260cps gain (1700cps compared with the expected 1440cps) is because the V32bis (or V42bis ? I'm not an expert...) protocol is able to more or less strip out the start/stop bit of the characters, transmitting less than 10 bits/char. I guess I could do a little better by disabling the modem compression, but why bother... By the way, Taylor UUCP protocol 'g' is much more efficient by changing the default packet size from 64 to 1024 bytes (gains about 10% throughput). The 1024 bytes packets allowed me to transfer 240cps exactly on a 2400bps (V22bis) modem, difficult to do better ! But I think it's only possible if you have Taylor at both ends. -- Pierre Beyssac FreeBSD@home: pb@fasterix.frmug.fr.net NetBSD, FreeBSD, Linux -- Il y a moins bien, mais c'est plus cher.