[aprssig] smart IGates

[Lee Bengston]

There's been past discussion on this list about filtering internet to
RF traffic, and with good reason given the propensity for congestion
on the RF side.  There's also been discussion about the handling of
duplicate packets by the IS servers, and the situation where packets
are not always recognized as duplicates because of the "mangling" of
packets by certain firmware or software.

I haven't researched all of the capabilities of the various IGate
capable software, but looking at the few that I have, I don't see
options for things like distance limits or hop count limits that can
be imposed in the RF to IS direction.  In my area, it's probably safe
to assume that if I receive a packet with a hop count greater than 1,
or if I receive a packet further away then say 25 miles, it's probably
already been gated to IS by an IGate closer to the packet source, so
the preference would be to ignore it.  Another feature I've seen
implemented in the IS to RF direction that would be interesting in the
RF to IS direction is a hold-off timer.  Basically hold off and listen
for the same packet on the internet side that you just received via
RF.  If you don't hear it after 5 seconds, for example, then send it
into the IS - otherwise drop it.  Of course if a packet has been
altered before or during gating, it may not be recognized as a
duplicate by the IGate that has held off, but that situation is what
it is.

One glaring omission among the software packages I've looked into is
UIView, so perhaps it can do some of these things arleady?

Regards,
Lee - K5DAT