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[aprssig] Igate,APRS-IS, Messaging

AE5PL Lists HamLists at ametx.com
Sun Jun 18 12:39:00 UTC 2006

> -----Original Message-----
> From: kb2scs at optonline.net
> Posted At: Sunday, June 18, 2006 7:26 AM
> Subject: [aprssig] Igate,APRS-IS, Messaging
> > Bob WB4APR wrote...
> >  Thanks for the test, but your test did not test that function.
> >  Yes, everything gets to FINDU.  But only messages go  back 
> to RF if 
> > an IGate recognizes a local station AND  the SERVER that it is 
> > connected to recognizes the  station as within the range filter of 
> > that IGate.
> Steve I know that you answered this already but I am still 
> confused by the above statements.
> Here is how I think that the message function of the APRS-IS works.
> No matter what filter a connected station to the APRS-IS is 
> using be it an Igate or just a client station all messages 
> are passed to all connected stations. The sending station 
> does not need a valid position. Acks are sent also to all 
> connected stations even if the sending station does not have 
> a valid position.

You are basically correct.  Bob's statement about server operation is
incorrect.  When an IGate connects to a filter port on a server, it
receives all packets per the filter set PLUS any messages (and
associated posits from the sending station) addressed to the IGate PLUS
any messages (and associated posits from the sending station) addressed
to stations gated to APRS-IS by the IGate.  This "last heard" function
on a filter port allows the IGate to see messages destined for station
in the local RF area.  Nothing special has to be configured in the IGate
for this to work.  This allows the IGate to get a properly filtered data
stream and see only messages destined for the IGate or stations heard on
RF by the IGate.  This "last heard" functionality has been on filter
ports since the very early days of the port.  Remember acks are just
standard message packets.

The IGate is in complete control of what actually gets gated to RF.


Pete Loveall AE5PL
mailto:pete at ae5pl.net 
(Author of javAPRSSrvr)

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