Maybe the following experience is of interest to you:
I've just tried your ax25-2.1.42-6.diff.gz with the new x25 timer handling.
The performance problems which I've reported some time ago disappeared
with this patch.
I've also successfuly established x25 connections on top of isdn to
non-Linux sites (operating in ISO-8208 DTE-DTE mode) recently.
One Problem occuring during those tests was that apparently some of my
peer's ISO-8208 implementations only support one locical channel which
must be lci 1. The lci allocation algorithm in your code starts
allocating the lci=2 for the first socket. The effect is that those
silly peers refuse to accept the call request (with Diag 71).
I've worked around this by some dirty hack. But I think in the long term,
some configuration option restricting the valid lci set should be provided.
Should I look after this?
Henner