From: root@ssw.de (Benno Lange)
Newsgroups: comp.dcom.modems
Subject: Re: Slow Worldblazer to Worldblazer uucp transfers
Date: 28 Sep 92 18:15:34 GMT
Organization: Lange Software GmbH


In article <wa8ndwg.gerg@netcom.com> gerg@netcom.com (Greg Andrews) writes:
>In article <Buzz94.Bwz@nshore.org> steve@nshore.org (Stephen J. Walick) writes:
>>As quoted from <1992Sep22.035100.3719@kilowatt.uucp> by root@kilowatt.uucp (Kilowatt admin):
>>
>>+---------------
>>| 2200 cps is about right for local Turbo PEP to Turbo PEP. I am running
>>| a 80486-33 with Consensys SVR4, FAS installed running the modem at
>>| 115,200 baud!!!! My friend has a SPARC I with 38400 to the modem (both
>>| are WorldBlazers). We get about 2100-2200 (mostly the upper half of
>>| that range) throughput. And I have a noisy line! (No spares left in
>>| the trunk to use)
>>| 
 some stuff deleted
>
>Well, he mentioned that he sees the ~3500 cps on UNcompressed data.
>Remember that a WB-to-WB connection will choose V.42bis compression
>or none at all (if you've turned compression off).  The modems will
>not use the old Telebit LZ compression.  That's only for compatibility
>with older PEP modems.
>
>The reason he gets "only" 3500 cps is because his friend's port speed is
>38400 bps.  With uucp's 91.4% efficiency (64 byte packet), you would expect
>to see throughputs around  3840 * .914 = 3510 cps.  Looks like he's right
>on the mark.
>
>>
>>You say: "Telebit only claims 24000..." -- if you read the quote above
>>(and/or your manual), I don't think you'll find any foundation for that
>>statement.  The figure(s) used: 23,000 bps without data compression ...
>>70,000 bps when V.42bis is used with Turbo PEP.
>>
>
>If you want to get that nit picky, the wording is "...up to 70,000 bps..."
>                                                      ^^^^^


We did some tests between two machines during the weekend using 2 WBs.
One was hooked up to a 486/33 w 16550 + SVR4 + FAS + HDB-uucp,
the other one to a MOTOROLA Delta 68040 w SVR3 + taylor-uucp 1.04.
Both machines and modems have HW handshake, spoofing and
V42bis data compression enabled. Both WBs have LA5.00W ROMs.

We had previously used an interface speed of 19.2kbps and got a
xfer-rate between 1600 and 1750 bytes/sec on compressed news batches.
(as reported in xferstats of uucp)

Switching to 38.4kbps resulted in a xfer-rate between 1950 and 2040 bytes/sec.
Increasing the interface speed to 115.2kbps did NOT increase the xfer-rate
any further.

The rate of ~2000 bytes/sec seems to be a bit low if I see other people
measuring xfer-rates of ~2200 bytes/sec ?
What have we done wrong ?

I think that we have hit the limit of 23kbps throughput for TurboPEP !!
(23000 * .914 / 10 = 2102 bytes/sec)  Comments ?

Checking the modulation rate registers show even values well above 23kbps:
    s70 ~24000      s72 ~26500
(I don't know what 'modulation rate' really means. But I think that they
give a measure of the real xfer-rate on the line. Greg could you shed some
light on this ?)

IMHO the 70kbps mentioned in the WB manual seems to be only the data rate
between modem and computer and NOT between modem and modem !!

The interface speeds higher than 38.4kbps seem only to be good for sending
mostly UNCOMPRESSED data.
(tests with a compressable file show xfer-rates of ~3300 bytes/sec @ 115.2kbps)


-- 
Benno Lange                     Lange Software GmbH
				Hornmoldstr. 21
E-Mail...: bl@ssw.de            D-7120 Bietigheim-Bissingen
Voice....: +49-7142/66990       Germany
Newsgroups: comp.dcom.modems