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[aprssig] APRS routing strategies

Henk de Groot henk.de.groot at hetnet.nl
Tue Feb 15 20:40:40 UTC 2005


Jason Winningham schreef:
> 
> Why would you invite someone to use a path of WORLD?
> 
> Details, please!

Maybe this will help (note the date on the "Sent" header). This is the 
original I wrote (including typo's I noticed).

Kind regards,

Henk.

-----------------------------------
From: bounce-aprssig-1679 at lists.tapr.org
[mailto:bounce-aprssig-1679 at lists.tapr.org]On Behalf Of
henk.de.groot at hetnet.nl
Sent: Thursday, August 30, 2001 7:04 AM
To: TAPR APRS Special Interest Group
Subject: [aprssig] New generic calls proposal


Okay, now that we exchanged arguments I have a proposal. Please
shoot at it.

----------------------------------------------------------------------------
Introduction of 4 new generic digipeater calls
----------------------------------------------

This proposal is to introduce 4 new generic digipeater calls, living
besides the existing WIDE, TRACE and RELAY calls (thanks to Bill Vodal
for the names :-)). These are:

LOCAL, REGION, WORLD and IGATE

A USER can expect the following from the APRS network when using these
paths:

LOCAL
* Coverage of at least 20 km (12 miles) from the current location

REGION
* Coverage of at least 50 km (30 miles) from the current location

WORLD
* Maximum socially acceptable coverage

IGATE
* Packets will make it to at least 1 IGATE

For consistency the user must be able to rely on these expectations so
he is the one who selects a wanted coverage for his packet by picking
the right name.

The digipeater shall substitute the paths with generic paths to make
it tollerate call-changes and dynamics in availability.

LOCAL
-----
This is a direct route to and from the digipeater. A
digipeater can add one more WIDE to provide some
redundancy to cover signal fluctuations for mobile use.
For a high-digi with a large coverage area a WIDE shall
not be added.

A user can expect when using this path:
* Coverage of at least 20 km (12 miles) from the current location

Proposed conversion:

Input:

PE1DNN>APRS,LOCAL (for fixed station)
PE1DNN>APRS,RELAY,LOCAL (for mobile station)

Output of 1st digi (same for fixed and mobile!):

PE1DNN>APRS,DIGI*,WIDE   (first digi has range < 20 km (12 mi))
PE1DNN>APRS,DIGI*        (first digi has range => 20 km (12 mi))

REGION
------
This is a route with 1 or 2 hops and from the digipeater covering a
defined area like a county, a vally etc. For a high-digi with a large
coverage area less hops can be used.

A user can expect when using this path:
* Coverage of at least 50 km (30 miles) from the current location

Proposed conversion:

Input:

PE1DNN>APRS,REGION (for fixed station)
PE1DNN>APRS,RELAY,REGION (for mobile station)

Output of 1st digi (same for fixed and mobile!):

PE1DNN>APRS,DIGI*,WIDE2-2 (all digis have range of about 20 km (12 mi) each)
PE1DNN>APRS,DIGI*,WIDE    (1st digi 20 km, second range > 30 km (18 mi))
PE1DNN>APRS,DIGI*         (first digi on a high loc, range > 60 km (40 mi))

In general, use as many hops as you need to cover about 50 km (30 miles)
radius.

WORLD
------
This is a route with the maximum number of hops that can reasonably
tollerated in the area.

A user can expect when using this path:
* Maximum socially acceptable coverage

Proposed conversion:

Input:

PE1DNN>APRS,WORLD (for fixed station)
PE1DNN>APRS,RELAY,WORLD (for mobile station)

Output of 1st digi (same for fixed and mobile!):

PE1DNN>APRS,DIGI*,WIDE4-4

The number of hops is based on historic data, what is common practice
and accepted use in your area. This only needs to be adjusted when
there is a trend to more (or less) traffic detected.

IGATE
------
This is a route with the number of hops that reasonably has to be used
to reach at least 1 IGATE.

A user can expect when using this path:
* Packets will make it to at least 1 IGATE

Proposed conversion:

Input:

PE1DNN>APRS,IGATE (for fixed station)
PE1DNN>APRS,RELAY,IGATE (for mobile station)

Output of 1st digi (same for fixed and mobile!):

PE1DNN>APRS,DIGI*,WIDE2-2

The number of hops is based on historic data, the pennetration of IGATEs
in your area. IGATEs come and go, but the density is more or less
constant. The path can be set up to cover about 3 working IGATES in
dense areas. The replacement call is a generic call to is will be
tollerant to IGATE moves and call-changes.

Avilability
-----------
Direct for DIGI_NED, will be included in the next default-file.

Add the following rules to DIGI_NED.INI:

;skip any path occuring before this call, this is needed because
;we don't want the digi to act on RELAY in this case because
;otherwise the actual coverage doesn't match the wanted coverage
;due to the extra hop on the wide-digi.
preempt: all LOCAL
preempt: all REGION
preempt: all WORLD
preempt: all IGATE

Remover the existing
digipeat: 1 local 1
and
digipeat: 2 local 2

Add the following rules:

digipeat: all local all new DIGI_CALL
digipeat: all region all new DIGI_CALL,wide
digipeat: all world all new DIGI_CALL,wide5-5
digipeat: all igate all new DIGI_CALL,wide3-3

Of course you have to change the hop-counts to match your environment,
if possible you should fullfill the users expectations as described
above so the user knows what to expect when using a certain digipeater
call. Note that path specifications occuring after LOCAL, REGION,
WORLD and IGATE shall be wiped out. If the user doesn't like that he
should use the old generic digipeater calls.

For UIview and UIDIGI support contact the authors of those products.

Phase in:
---------
Temporarly both the old and the new method needs to be supported. This
is possible because the DIGI can look for any of the new generic calls
anywhere in the string. The new generic calls can be put at the end
of the path. A user who wants to reach the world can use:

PE1DNN>APRS,WIDE,WIDE3-3,WORLD

When the packet reaches an old digi, then this digi will just use the
old WIDE and WIDE3-3 calls. When the packet reaches a digi that implements
these new calls, then the path before WORLD is stripped and WORLD is
replaced by an acceptabe path for that area.

In line with Bob's I and N overlays (for ID and NOID digis) we could use
overlay A for an Advanced digi supporting LOCAL, REGION, WORLD and IGATE
calls...

Henk - PE1DNN, August 30 2001.






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