[plug] What you give shall you receive....

[Michael Hunt]

Garth,

This is weird. I gather you understand that 56K is a digital technology that
is only achievable by the ISP (or ppp server you dial into) installing
digital lines to their premise. This takes out two conversion processes that
used to happen at the exchange nearest the ISP.

e.g. Old analogue scenario

Call made by modem
Signal changed from digital (your PC) to analogue
	by modem
Signal changed from analogue to digital by exchange
Exchange talks digital to exchange nearest your ppp server
Signal changed from digital to analogue by exchange
Signal changed from analogue (ppp server) to Digital
	by modem

Modulation Process occurs four times (twice at modems, twice at exchange)
Max Speed: Theoretically 33.6K


e.g. New digital scenario

Call made by modem
Signal changed from digital (your PC) to analogue
	by modem
Signal changed from analogue to digital by exchange
Exchange talks digital to exchange nearest your ppp server
Exchange nearest your ppp server talks digital to ppp server

Modulation Process occurs two times (once at modems, once at exchange)
Max Speed: Theoretically 56K

Of course one other limitation is that the modem can only do this in one
direction, so 56k download speed 33.6k upload (but this is only theoretical,
practice shows that this rarely happens).

Now my theory is this (after having explained all of the above), is that
line qualities means that one of your modems is actually talking faster than
the other. I believe that the firmware of the modem could also be inhibiting
download speeds based on weather the modem was the calling modem or the
called modem. If this speed happens on the calling modem then the above
would be presumed to be correct. A test would be to get the other modem
(i.e. the called one) to call the first one (i.e. the calling one).

But theoretically none of these higher speeds should be happening at all.
2.6k is very good for a 33.6 but 5.6 is a 56k speed.

Hope this is of some help Garth

Michael Hunt

> -----Original Message-----
> From: owner-plug at linux.org.au [mailto:owner-plug at linux.org.au]On Behalf
> Of Garth Atkinson
> Sent: Friday, October 22, 1999 6:20 AM
> To: plug at linux.org.au
> Subject: [plug] What you give shall you receive....
>
>
> Hello Pluggers
>
> Bruised and bloody by some modem wars I seek assistance.
>
> I have configured a simple PPP link between two 56K modems. In one
> direction I can achieve the wonderful throughput figure of 5.6 Kbytes
> per second (measured by ftp'ing a 1 Meg file). In the other direction I
> get exactly half that figure (2.8 Kbytes per second, measured by ftp'ing
> a 1 Meg file). Both modems are external Hayes Accura 56K+.
>
> Whats going on?
>
> Garth
>
>