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[aprssig] Excessive beacons/connects by "smart" IS clients

Gerhard.F5VAG f5vag.eu at gmail.com
Sun Apr 15 13:11:25 UTC 2012


The various APRS-IS servers are exposed to an increasing number of
mobile TCP/IP clients which tend to send at beacon rates exceeding
reasonable limits. This issue will rapidly increase with the increasing
number of "smart" portable devices.

In these cases aprs.fi sends the kind warning
"This station is transmitting packets at a high rate, which can cause
congestion in the APRS network.".
http://f5vag.eu/tmp/APRS_FI_info_FNaaa-9.html

However, seen from the server to which the client is connected, the observation
is much worse. In certain cases the server has to handle connect/disconnect
cycles below ten seconds over considerable time periods:
http://f5vag.eu/tmp/JavServUser_FNaaa-9.html

Many of the excessive beacons are fortunately dumped by the entry point
server and not forwarded to the main stream, e.g. dupes.

In my view it is not reasonable to sent beacons with an interval of less than
five minutes with TPC/IP connections, but to use UDP. Many T2 servers provide
this possibility on port 8080. It drastically reduced the overhead for
the servers
and the clients by avoiding the connect/disconnect overhead.

Even for clients using UDP the beacon interval should be limited to 30
seconds. I know that this limits the resolution to 0.8 km @ 100km/h
(0.5 miles @ 60MPH) and think this is a reasonable limitation.

In any case, more "smart" beaconing should be used..

Any comments?

.....
73 de Gerhard, F5VAG
http://f5vag.eu, france.aprs2.net

P.S.: The callsign in the above links is certainly not real.



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