[aprssig] APRS Priority bit

Robert Bruninga bruninga at usna.edu
Tue Aug 25 12:34:01 EDT 2009


> I see that the concept is to be able to shut 
> off all non-essential traffic at the 
> digipeaters.  

I wouldn't say it that way.  I would say it along the lines of
"to be able to moderate the traffic based on priority".  In most
cases this is not a shutting off, but a "toning down" of hop
length...

> Why don't we just use the subnet concept?  
> Doesn't UIView support subnet? Since this proposal would 
> require modification to the digi's programming either way.  
> But then again, how to mic-e packets fit into the subnet 
> concept?  Isn't the TO call used for part of the position?

Using the overlay-case-bit does not require any modifiction al
all existing software.   But using a SUBNET would, else no one
would see the priority traffic...


Bob
> 
> On Wed, Aug 19, 2009 at 10:05, Robert Bruninga 
> <bruninga at usna.edu> wrote:
> 
> 
> 	APRS needs a priority bit so that the network can make
decisions
> 	about traffic during times of stress.
> 	
> 	We have been looking for a way to include a PRIORITY bit
in all
> 	APRS packets for many years, and there are 3 available
bits in
> 	the standard packet, but they cannot be used until
UI-view is
> 	obsolete.
> 	
> 	This last week we did find that one of these bits IS
backwards
> 	compatible with UI-view and so we would like to move
forward on
> 	this issue.  Please read:
> 	http://aprs.org/aprs12/priority-bit.txt
> 	
> 	Basically, we will use the CASE of the OVERLAY byte to
indicate
> 	ROUTINE or PRIORITY.  If the overlay byte is UPPERCASE
or
> 	missing, then the packet is ROUUTINE.  If the case of
the
> 	overlay byte is -lowercase- then the packet is PRIORITY.
> 	
> 	Last week testing confirmed that UI-view and most other
clients
> 	will display these lower case overlays, or can be
updated to do
> 	so, so this has now been added to the APRS12 addendum.
> 	www.aprs.org/aprs12.html
> 	
> 	This combined with the OPERATOR PRESENT bit which has
been
> 	defined for years, gives operators an easy way to
differentiate
> 	assests of immediate value during times of stress and to
> 	minimize or ignore routine or unattended systems as
needed.
> 	
> 	DIGIPEATER code can add a SYSOP parameter that allows a
sysop to
> 	designate a local emergency and to implement a MINIMIZE
function
> 	that lets the digipeater make decisions on traffic load
based on
> 	packet priority or other parameters.
> 	
> 	Bob, WB4APR
> 	
> 	
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> 	
> 
> 
> 
> 
> -- 
> Wes
> ---
> We are learning a lot more about Chicago-style politics than 
> I ever wanted to...
> 
> 





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