From: Riley Williams (gqrlghn.ogzntbxqj@aussie.com.au)
Date: Sat Jan 19 2002 - 01:20:01 EET
Hi Demetre.
> I know that SCS has a firmware that allows you to make your PTC-II a
> modem that provides IP over SLIP, but I am not interested in that
> since both ends on HF must use the same firmware and hardware and
> then again IP over HF is a bit too much to desire!
I'm no expert on HF as I'm not licensed for it, but there is one claim
in there that is just plain rubbish, and easy to prove as such...
> ...both ends on HF must use the same firmware and hardware...
...is demonstratably false even by a complete moron, and no better
example of this can be found than AX.25 itself, which works quite
happily not only with different firmware but with different brands
using different chips to control them. Ethernet in all of its many
guises also proves the same fact.
The actual requirements are quite simple:
1. The signalling used for the link employs a standard protocol.
To take FSK packet as an example, the two ends must employ the
same shift between the mark and space frequencies, must shift
between them at the same frequency (the Baud rate), must use
the same number of bits per character (the Data Length), and
must use the same framing format (the Parity and Stop Bits).
This corresponds to level 1 (the Physical layer) of the ISO
diagram.
2. The packet protocol must be the same for both ends of the link.
This corresponds to layers 2 through 7 of the ISO diagram as
applicable to the system under discussion.
Providing both of these conditions are met, the link is possible.
As to whether it is feasible, that depends far more on the details
of the various protocols used than on anything in the above.
Incidentally, the "same hardware" requirement claimed in your quote is
an issue with requirement (1) above, and the "same firmware" requirement
is an issue with requirement (2) above, so those are NOT the same thing.
Best wishes from Riley.
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