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[aprssig] APRS routing strategies

Robert Bruninga bruninga at usna.edu
Wed Feb 16 23:02:23 UTC 2005


>>> henk.de.groot at hetnet.nl 2/16/05 5:02:45 PM >>>
PE1DNN>APRS,CALIFO

Is in my opinion much better than

PE1DNN>APRS,CA4-4

But there is absolutely no way that a packet in California
can even remotely be deliverd to all of california
on a single 1200 baud chanel.  Hence it is silly
to have a path called CALIFO

CA4-4 on the other hand can go to a limited
subset of California within 4 hops of the users
location and if that is too much QRM in a 
given area, then the digis can trap it out...

I think users are smart enough to figure out
what a digipeater is and what range each one
means.  After all, they user VOICE repeaters all
the time and have an idea what range to expect...


>How does the *user* detemine it must be 4 hops? 
>Why not 3 or 5? Better yet, does the user care? 

Absolutely he should!  He should be using 3 if he
needs to go 3 hops and he should never use
5 as he will QRM too much area...

>I think not, his intent is to spread his packet 
>over California.

Which means he is a totally clueless appliance
operator and should not be using the radio..

>Now having the digi expand CALIFO into a suitable 
>path will make it easier for the user. 

making it easy for the user to SPAM packets over all
creation with no knowledge or responsibility for the
impact is exactly what we should NOT be doing.

>Of course when it is just not physically possible 
>(because of the local traffic conditions for example), then 
>it is not possible. There are no guarantees,

Then there is no need whatsover to even suggest that
there is a possibility. 

>In this scenarion the user never has to change his setting 
>because for example in one corner of California he would 
>have to use WIDEn-N, in another area CA4-4...

Every local topology and network and need and use of
APRS is different and quite dependent on the senders need
at the time.  Even implying to users that any path other
than a local 2 hop generica path is a one-size fits all solution
is just overlooking our function as communicators...

>I invite you to come up with some better aliases. 

OK, how about WIDEn-N where N selects how far you want
to go and at what QRM expense to the network.  This definition
works everywhere... to anyone with a clue what a VHF radio
is and what a repeater (or digipeater is)...

>The alias should refelct the intent of the user. 
>Where does *he* want his packets to go to. 
>Think about the end user, *what* does he want. 

Well, -2 means he wanst to go 2 hops. first to his local
VHF range and then to one tier beyond that.  -3 is similarly
very obvious even to a fence post...

>He does *not* want to know hopcounts, he wants his 
>packets *to go somewhere*.

Then he had better look at a map and look at the PHG circles
of his station and surrounding stations and decide what he
should do at that place at that location and with those asets
and that traffic density to get the job done without causing
maximum QRM to everyone else.

We are supposed to be communicators, not appliance 
operators...

> Already EVERY packet goes to world.

>No, sometimes one hop is enough to reach an IGATE and 
>sometimes more hops are needed.

Yes, that is why I recoemmend WIDE2-2 as a univerasal path..

>> This idea makes no sense in any sense of the word, since
>> what limits APRS is NOT RANGE, but BANDWIDTH and
>> LOAD.  In Kansas it is safe to send ones packets out
>> 300 miles in all directions.  In LA, 30 miles is about right.
>> Thats a 100 to 1 difference in area.
>
>But in LA you may want to use LNKn-N paths to go beond that.

No that was to serve long haul traffic along a long linear
corridor out in the middle of now where and generate less
than 3% of the QRM that the same distance would require
using ageneric path..  Also it was a dead-end
idea which has been completely abandoned.

> APRS is limited not by mileage but by the ALOHA range 
> (a 100% channel) and it can be ANY PHYSICAL SIZE.

>So how is the user to *know* what path is permitted. Especially a 
>traveler. 

Very simple, look at your radio.  Look at the digis listed on the
front panel.  Click on it.  See the STANDARD nomenclature
for that digi.  If it says R,W3,S3, then that means that
WIDE3-3 or SS3-3 is recommended in that area and anything
larger will be truncated.  etc...  Very easy, very intentional,
very specific for that area, and perfectly matchted to the
topography and load in that area...  what could be simpler?
And it works right now, today, and does not take a total rebuild
of over 1000 digis all across the country that took 13 yers
to build...

>So I will step down from my soap box and watch the 
>"new paradigm" stopgap "solution" unfold. Up to now I only 
>saw the confusion grow, kudos to anybody that still knows 
>how the configure their digi according the most recent 
>proposal (where "most recent" means just that, a moving target).

Sorry that you see open discussion and the accomodation of
inputs from everyone on the SIG as being a moving target.
I see it as an open technical discussion, trying out ideas,
constanlty updating the proposals based on good feeback
and arriving at what appears to be a consensus.

The new Paradigm has been in place in LA now for over a week.
>From what I hear it has made a BIG difference...  The load is
down, 5W trackers can get in better, yet just about everyone
can still see just about everyone...

Everyone that has tried it has had nothing but positive 
comments on the improvement in the network.  Sure there
have been LOTS of negative comments and "opinions"
most about the "confusion" factor and the typical
"who-moved-my-cheeze" variety.  And yes, frustration
at how it evolved over  time.  But try it.  You'll like it!

> Itis your APRS protocol, if you insist to keep Kantronics 
>boxes forever then so be it.

Duh, you give me something to upgrade those boxes that
all 1000 digipearters will go out and replace it with, and
I am all for it!  But in the mean time, Im trying to fix what
we have with what we got.  I WELCOME smarter
digipeaters....but they must be seamlessly introduced
so as to not require wholesale replacement of everything
everywhere (a 10 year process)  until they can work at all.
consistently for users...


de Wb4APR, Bob





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