zjdg11@hou.amoco.com (Jim Graham) (06/25/91)
In article <78@uis-oc.UUCP> bob@uis-oc.UUCP (Robert J. Mathias Jr.) writes: > In article <1991Jun18.123604.9315@hou.amoco.com> zjdg11@hou.amoco.com > (Jim Graham) writes: >> I'll take V.42/V.42bis over MNP4/5 any day..... > Some of us like to squeeze the last ounce of speed out of our equiptment like me, for example....very definitely. when I'm at home, I pay for just about every call, including local calls, on a per-minute basis. also, I don't have a lot of patience to sit and wait on a slow modem (virtually nil, in fact). Add those up, and look at my last month's phone bills, and even the slightest improvement helps. > so we poor miss guided souls prefer to disable V.42 and go with MNP4. > As to V.42bis and MNP5, V.42bis is the winner but since I do alot of > file xfers of ZIPed files, I also disable compression on my modem. Ok, we agree that V.42/V.42bis beats MNP4/MNP5 --- so why use MNP4/MNP5 if you have a choice? with V.42bis turned on, I still see an increase in throughput on Zmodem file transfers of ZIPped files (115 -- 125 percent efficiency as opposed to 97 percent seems common), so how does turning if off help? So, what am I missing here? I'm honestly curious as to why so many people seem to talk about the evils of V.42bis on file xfers when I see such an improvement....that is, btw, measured stats on BBSs and from DSZ. (The stats are somewhere in a big pile of paper at home....and probably got tossed in this weekend's cleaning up, but if anyone is really interested, I could easily take note of some more.) --jim Standard disclaimer....These thoughts are strictly mine, not my employer's. ------------------------------------------------------------------------------ Share and Enjoy! (Sirius Cybernetics Corporation, complaints division) 73, de n5ial Internet: zjdg11@hou.amoco.com or grahj@gagme.chi.il.us Amateur Radio: TCP/IP: jim@n5ial.ampr.org (44.72.47.193) Packet: BBS went QRT for good...still searching for new one. ------------------------------------------------------------------------------
mju@mudos.ann-arbor.mi.us (Marc Unangst) (06/25/91)
zjdg11@hou.amoco.com (Jim Graham) writes: > So, what am I missing here? I'm honestly curious as to why so many people > seem to talk about the evils of V.42bis on file xfers when I see such an > improvement....that is, btw, measured stats on BBSs and from DSZ. (The stats Because they don't know what they're talking about. MNP5, which is the MNP implimentation of compression, tries to compress already-compressed data, and ends up making the data bigger, meaning you usually see a throughput DROP when you enable MNP5 on a connection that's sending compressed data. V.42bis, on the other hand, doesn't bother compressing the data if it ends up bigger after compression than it was before -- sort of like compress(1) without the -f switch. Anyway, people who speak the evils of using V.42bis on compressed file transfers are thinking that it does the same bad things that MNP5 does, which is not true. Just as some additional data points: I regularly get 1120cps or so using Zmodem to transfer .ZIP files over a 9600/V.32/V.42/V.42bis connection. On the other hand, UUCP throughput (sending compressed news batches over a V.32 connection) jumped from about 750cps to about 990cps when I turned off MNP5 and only used MNP4. -- Marc Unangst | mju@mudos.ann-arbor.mi.us | "Bus error: passengers dumped" ...!hela!mudos!mju |