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[aprssig] APRSLink

Robert Bruninga bruninga at usna.edu
Fri Jan 13 17:53:27 UTC 2006


>>> HamLists at ametx.com 01/13/06 10:15 AM >>>
>The messaging software doesn't dictate paths. 
> The IGate software dictates the path. 

I think that is what he was asking for.  IGates have
to be smarter, more selective, and their owners
have to be attuned to the local area.

> A basic premise that your post assumes is that the
> path a station is heard via is the same path that a 
> packet can be returned to that station.  That is an 
> invalid assumption...

He did not say to use the exact reverse path, he said
to use "that information" to better return the message
without flooding the entire network over the entire
state when the incoming path is now clearly known.

I think reverse-pathing cannot be  implemented 
simplistically, but heuristically.  MOST of the time the
reverse path will work just as it came in.  We need
to add intelligence to the algorithm to take care of
the cases where it is not working, and software can
be smart enought to do this.  It gets an ACK when
scuccessful, so it may try the exact reverse path
a few times and if that doesnt work then try
another path.

For example, the IGate knows the APRS physical location
of the receipient  and It should know its own first hop
in major direction.  An I gate that needs a two hop to
a station that finds the reverse path does not work
would then switch to a DIRECTED first hop in the
general direction followed by a generic 1 hop to the
final hop to flood THAT area only and not all 360 
degrees.

I think that is what he meant by we need to start using
the information in the paths to better target messages
which are the only APRS traffic that is point-to-point and
which can be delivered as efficiently without flooding.
IT cannot be simplistic, but needs to have  heuristics
added in to cover all those examples you mention.

de Wb4APR, Bob

> -----Original Message-----
> From: Bill Vodall
> Posted At: Friday, January 13, 2006 8:51 AM
> Subject: RE: [aprssig] APRSLink
> 
> It's time to upgrade messaging software to use direct paths 
> instead of flood paths.  We now have the new wideN-N scheme 
> that gives the full packet path so it's a natural next step 
> to start using that information.
> 
> It's the FLOOD, not the messaging, that causes the problems.

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