modem speeds, V.90, etc

[Drew Parsons <dfparsons@ucdavis.edu>]

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