Re: modem speeds, V.90, etc
Ok, I am not that sure about wvdial, but if you use pppd and the
chatscripts the key is to wait for something after the connect message so
that you can still get the connect message in your logs.
Once you get the connect message in your logs, you can adjust it to report
the right speed. If it says 115200, then you need to add an atw2 to your
init string (This is a standard command across 95% of modems, and it works
on my Xircom).
As for your question on jargons, all speeds in the serial world are bits,
not bytes, so 14KBytes/sec is pretty good, and that is using software
compression. The rs232 protocol which the serial ports use (or the
internal serial stuff in internal modems such as the one you are using) is
asyncronous, so it uses a start bit, 8 data bits, and a stop bit for each
byte, giving you a factor of 10, not 8.
I hope this gets you pointed in the right direction,
Charlie
On Sat, 30 Oct 1999, Drew Parsons wrote:
> I've got a question about making modem connections via ppp. I want to
> be sure I'm configured for establishing the fastest possible
> connection, and I'd like to ask those of you who know to check my
> numbers with me.
>
> I have a V.90 (56K) capable modem (Xircom RealPort if you're
> wondering), and I *think* the receiving modem (my university's modem
> pool) at the other receives 56K connections, though I'm not absolutely
> sure. I'm able to establish a connection using wvdial, it's all working fine, but
> I want to confirm the speed, and I'm not completely sure how to do
> that.
>
> Now the Linux ppp tools don't seem to talk in terms of "14K", "28K",
> "56K" modem speeds. They seem to refer directly to the serial port
> rate, which I have set at the apparent maximum of 115200 baud (so here's the first
> question: is that 115 kilobytes or 115 kilobits? The former, I
> believe.) The difference in speed jargon makes it difficult for me to
> be sure I have a proper V.90 connection. No log data (eg
> /var/log/ppp.log) seems to tell me what speed connection I have.
>
> xnetload tells me that my maximum throughput is about 14745 B/s. So
> does this mean I only have a "14K" connection? Or do I multiply by 8
> to find I have a throughput of 115 kilobits (and am achieving the
> maximum speed)? (I'm aware that with compression I can get a 115Kbit/s
> information flow on a 56Kbit/s modem). I suspect here it's the latter, but the question still remains
> of whether the carrier speed is "V.90 (56K)" or "34K" or what.
>
> Can anyone spare a short word to explain this business a little more
> clearly? The PPP How-To doesn't really go into these questions.
>
> Thanks,
>
> Drew Parsons
>
>
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