On Sunday 08 July 2001 10:59, Tony Alfrey wrote:
> On Saturday 07 July 2001 09:04 pm, Bruce Marshall wrote:
> > On Saturday 07 July 2001 23:15, Tony Alfrey wrote:
> > > Both distros now set at 38K. I'll try 57K, but they already act
> > > differently.
> > >
> > > On Saturday 07 July 2001 09:23 am, Lee wrote:
> > > > On the kppp setup under devices set the moem speed for 57k
> > >
> > > <snip>
> >
> > Don't you really want to set them for 115200? You're missing a lot
> > of throughput if you don't.
>
> If my phone lines never allow a connection faster than 28K, why does
> setting at 115K improve the situation?? My impression is that the
> modem "tests" the capability of the phone lines to transmit clean data
> at high speed and, if that doesn't work, the modem kicks the baud rate
> to progressively slower speeds until the link is clean. Is this
> correct?
Uhhh.... here's why...
I assume you have a fairly recent modem that supports some of the compression
algorithms..... and I don't have the buzzwords handy. I think v42.bis is
one of them and I suppose the v.90 includes most of the algorithms.
Here's a look at one of my connection logs:
chat: Jul 07 17:40:38 CONNECT 44000/ARQ/V90/LAPM/V42BIS
Notice the mention of V42bis
(I may be getting my compression algorithms mixed up with error corr algs)
There are two speeds to be concerned with in using a modem:
1) The speed between your serial port and the modem,
2) The speed between one modem and the other (over the phone line)
You can't do much about (2) other than make it less than the modem might
want.. that is, you can't tell the modem to connect at a faster speed than
either it or the line quality can handle.
So that leaves (1). WHICH SHOULD BE SET TO THE HIGHEST VALUE POSSIBLE
(mainly 115200 which is the max for most serial ports and really the max
feasible rate with todays modems)
Reason: If your modem is doing data compression, it can achieve rates of 80K
actual throughput because of the compression. I have seen 80k rates on a
28.8 line for text type data. (binary doesn't compress well)
So even though your modem/line may be running at 28.8, you can achieve much
more throughput due to data compression by setting your serial port rate much
higher.
And the big thing? It can't hurt regardless of compression or line
quality.
It's a no-brainer issue.
--
+----------------------------------------------------------------------------+
+ Bruce S. Marshall [EMAIL PROTECTED] Bellaire, MI 07/08/01 12:09 +
+----------------------------------------------------------------------------+
"There is a theory which states that if ever anybody discovers exactly
what the Universe is for and why it is here, it will instantly
disappear and be replaced by something even more bizarre and inexplicable.
There is another theory which states that this has already happened."
_______________________________________________
http://linux.nf -- [EMAIL PROTECTED]
Archives, Subscribe, Unsubscribe, Digest, Etc
->http://linux.nf/mailman/listinfo/linux-users
