Owen Duffy owen at owenduffy.net
Thu Sep 25 18:01:24 EST 2014

Hello All,

Some thoughts on the issue:

I think the real issue here is the failure of source routing, whether
you give it some grand name like "New N Pardigm" or not.

There are numerous examples that demonstrate that you cannot depend on
hams, whether they operate end stations or 'infrastructure' (digis,
iGates) to "do the right thing'.

Hams doing what they want as individuals were responsible for the demise
of the old 'packet network' before its time, and the same problem occurs
with APRS.

So, if you drive outside Sydney or Melbourne for your annual holidays,
and you set your path for WIDE1-1,WIDE2-2, what is wrong with that?

Well the issue is that the optimal path is not a property of the mobile,
but its location. In some places, a single hop is sufficient to have a
high probability of iGate submission, in others, three hops might only
moderate probability of iGate submission.

Then there are the  effects of band openings (most mornings and evenings
in summer) where three hops may well get you from Sydney to Melbourne.

A possible solution is intelligent network infrastructure that controls
packet routing, and limits the lifetime of packets. It could also be
used to block misguided stations operating outside of reasonable
parameters on the shared radio channel.

That means finding a flexible routing platform for digis, especially
strategic digis that could be used to segment the network into local
areas as congestion dictates. Such a platform needs to be highly
interoperable, there is no room for a digi that does not decode some
popular trackers (eg the incompatibility between OT3 and Foxtrack/TT1).

Sydney is a most interesting case study, it has essentially no 'local'
digi and depends on three digis 40-60km out, and most packets that
originate or enter the area are repeated by all three digis so
increasing channel utilisation which in turn reduces the effectiveness
of the network for position reporting of mobile stations.

A filtering dig in each of the three locations to block traffic flow
from north to south, and south to north could be very effective in
reducing channel utilisation whilst still support high rate of iGate

The role of High Range and Mt Murray, both W2 digis located with 40km of
each other deserve review as under the "New N Pardigm", almost all
packets originating in Sydney and the Illawarra carried by one will be
carried also by the other.

At the same time, coverage of half of the M7 is patchier than a lot of
major highways outside of Sydney.

I think it is the infrastructure that deserves attention rather that
trying to educate end users.



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