[aprssig] Msg reply path

[Stephen H. Smith]

On 10/6/2013 11:44 AM, Andrew P. wrote:
> On a tangent from this, is there ever a reason to_initiate_  a message with either a WIDEn-N or SSn-N alias where N < n? I've seen cases like WiDE1-1,WIDE2-1, but are there any other cases that make sense (except possible smart reverse-pathing where it is obvious that the whole n wasn't needed)? Should digis that support SSn-N also support SSm-M where 1 <= m < n?
>
> Just a thought to stir the pot.
>
> Andrew Pavlin, KA2DDO


You don't need any explicit support at the digi for constructs like WIDE2-1 
(or hypothetically for something like SS7-3, etc).

The receiving digi simply sees this as a partially-used N-n path (i.e the digi 
"thinks" the packet passed through several digis already) and just decrements 
the -N by one count.   If it arrived as WIDE2-1, then it decrements to -0 
meaning NO more digipeats.   If something like SS7-3 arrived, it would go out 
as SS7-2 and be good potentially for two more digi hops.

I could see a potential use for "pre-decremented" SSn-N.  If someone wanted to 
broadcast a bulletin all over a major metro area, but not the remoter more 
rural parts of a state, something like SS7-4 would ensure it blankets the metro 
area including the outer-ring 'burbs, without blanketing the entire state. 
Could be of use for things like urban freeway tisups and closures due to major 
accidents, bridge failures, etc.

Or the recent flooding in Colorado to blanket the Denver-Boulder-Ft 
Collins-Greeley area WITHOUT also blanketing outlying areas like Colorado 
Springs, Pueblo, Glenwood Springs, Grand Junction, Durango, etc that a full 
CO7-7 would do.