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Re: AO40rcv and the Kenwood TS-2000



At 02:51 PM 4/8/2001 -0500, Timothy J. Salo wrote:
>If I were doing this, I would create two, layered protocols.  The upper
>layer protocol would be the end-to-end application protocol that has
>been discussed.

This is good in theory. Organizing the software that way would be a good 
idea. However, one has to be careful in practice.  Example:

>On packet links:
>
>   Amateur             -------------------------
>   Radio               | Type | Length | Value |
>   Protocol            -------------------------
>
>               ----------------------------------------
>   AX.25       |AX.25 ||     data (above)      || CRC |
>               ----------------------------------------

This only works cleanly if the protocol peer is inside the same box as the 
AX.25 protocol. If, as might be considered typical, the AX.25 is in one box 
(call it a "TNC") and the application protocol is in another box, you'd be 
forced to run some additional framing on the link (probably serial) between 
the TNC and the application. Yuck.

My point is that the reliability and framing protocol should be truly 
end-to-end, and the "ends" are often deeper in the system than they appear 
to be at first glance. Sometimes it is better to carry some overhead along 
than to strip off potentially useful fields too soon.

73  -Paul
kb5mu@amsat.org

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