AX.25 parameter negotiation phase question
 

Hi,

I am currently implementing a TNC using an ATmega32 and a CMX589a GMSK modem.

Currently, my main worry is how to handle the abovementioned.

The AX.25 v2.2 paper states that "Parameter negotiation occurs at any time"
(6.3.2, first paragraph).

What I am unable to read out of the protocol (Warning bells coming on,
"implementation dependent" flashing in big, red letters) is whether parameter
negotiation is mandatory to establish a connection (As opposed to just
using a predefined set of parameters), and, if it _is_ mandatory - what
happens if "my" TNC answers a SABM command frame with a UA frame (thus,
accepting the connection) and a XID command frame containing non-negotiable
parameters, then discarding the XID response from the originating TNC.

I am assuming the originating TNC will be able to accept the sent parameters,
and that a connection will be established. My concern is what happens if the
originating TNC should feel like renegotiating the parameters after the
connection has been established.
What happens then?

a) Will the connection be terminated, as "my" TNC does not send a response
to the XID command frame from the originating TNC?

b) Will the originating TNC try to keep ut the connection using the parameters
received in the XID command frame "my" TNC sent immediately after link estab

c) Implementation dependent?

Any thoughts appreciated. Thanks,

--
73 de LB1LF

Odd Erling, ARK

This message transmitted on 100% recycled electrons.