> This is a very un-informed response. "just can't deal with it very well".
> It is the Computer and serial port which "can't deal with it very well".
> Most modems do indeed RECOMMEND 115,200 port speed *if the computer can
> handle it*. Some modems recommend 57600. Not too many.
That is the case is some but not all instances. A while back I ran a test
when the ISP I worked for was having some problems. What I found was that
on the same port and on the same box. USR Sporters would only work
correctly at 38.4K, Supra modems would work at 56K and MultiTech BR
Rackmount and USR Couriers at 115K. I've also seen some 14.4K Modems that
would not work above 19.2K with any relibilty. The ability of the modem
to deal with the data coming in is also a factor. Sometimes droping the
port speed gives the modem time to deal with the data stream better as it
drops the Clear to Receive line more often and gets a lower rate of data
to deal with. Yes the ability of the serial port to buffer the data and
the CPU to be able to handle the amount of interupts is an important part
of the picture, but it is just one of many factors.
> V.34 compression optimumly compress 4->1. So a 28.8 NEEDS 115,200 for
> maximum efficiency. A 33.6 modem needs 134,400 !
Remember V.34 does NO compression. It is a speed spec only. I think you
may have been thinking of NMP5 and V42Bis compression each of which can
also be used on a V34 link. The amount of compression varies greatly on
what is being transferd. On E-Mail message downloads, text based web
pages, and telnet sessions it can help to a 4:1 ratio but is by no means
required.
Tom
----
Thomas C Kinnen - <tom@lcp.livingston.com>
[Test Engineer] - LUCENT Technologies - Remote Access Business Unit
<URL:http://www.livingston.com/> * <URL:http://www.lucent.com/dns/>
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