🚀 go-pugleaf

Wayne  Irving <lirving@tpgi.com.au> wrote:

> I am not a mac user but have a friend who is and has a problem

A modem is a modem is a modem ... (generally)

> She has a 28800 bps modem but can only connect at 19200

There are actually two places where your communication speeds may be
restricted:
1) computer to local modem (the port speed) - mixture of software and
hardware
2) local modem to remote modem - hardware only, this speed will be
negotiated automagically based on the connection quality over your
telephone lines.

> We thought it might be bad phone lines so we brought it to my place
> where I get 28800 all the time and could only get 19200

You brought "it" the modem or "it" the entire system? The difference
means debugging a modem (hardware) problem or debugging a system
(software/hardware) problem.

> the only setup options we can find are in freeppp goes 19200, 34400, 56000

The port speed setting that you make in FreePPP (or any other comm
software for that matter) is strictly to set a locked communication rate
between the computer and the modem. You need to lock the rate to permit
the compressed data to flow efficiently (lots of history due to
pre-compression modems and software protocols). You should be safe with
57600 kbps. Under unusual circumstances it may restrict the data speed
but this will be rare.

> These would be port settings and on windows you set the port to at least
> twice the modem speed

Same applies in the Mac world. This is a rule of thumb to avoid data
flow problems between the computer and the modem. You can set it as high
as possible, as long as your modem still recognizes the information from
the computer without crashing, stalling or not responding. The
compression capabilites really aren't much better than 2:1, normally, so
setting computer port speed to twice the modem line speed is fine.

IMPORTANT: make sure that FLOW CONTROL is set to HARDWARE (CTS only) and
NOT SOFTWARE (XON/XOFF) and NOT HARDWARE (CTS/RTS unless CTS only is not
an option). Again, this is important to the speed that compressed data
moves between your computer and the modem.

Life gets more complicated. As I mentioned above, you are actually
concerned with two data rates: computer/modem and modem/modem. Your comm
software will report one of these as provided by the modem. Check your
modem manual to see what the default is and how to change it if you want
to see the other.
  
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