On 01-Aug-99 Riley Williams wrote:
> In fact, the HDLC standard on which it is based already defines how
> such a system is to be handled, and precicely what should occur under
> all possible scenarios, so there's very little to be agreed on other
> than precicely what is meant by "Extended mode" as opposed to
> "non-extended mode".
>
> If you have access to the ISO standard for HDLC, look up the diagrams
> relating to negotiations between systems supporting both SABM and
> SABME modes to see the various possible timing diagrams, together with
> when the negotiation should result in SABM being agreed, and when it
> should result in SABME being agreed. Also in the same document are the
> timing diagrams for when one end is SABM and SABME capable, but the
> other only supports SABM, so that is dealt with as well.
erm.. I thought that the whole point of ISO layering was that the level 1
layer (which I presume to be HDLC) has nothing to do with the level 2 layer
(in this case (A)X25). So why are we confusing HDLC signalling (which is
based on one or more 'flag' bytes, some (optionally bit stuffed) octets of
data, a CRC and one or more flag bytes with some spurious layer of protocol
which may (or may not) be imposed on top of it?
AX25 works just as well in raw ethernet II frames on a wire or mpt1327
codewords on radio as it does with HDLC.
Dirk G1TLH
---
Dirk-Jan Koopman, Tobit Computer Co Ltd
At the source of every error which is blamed on the computer you will find
at least two human errors, including the error of blaming it on the computer.
