[aprssig] Universal WIDE2-2

[Robert Bruninga]

>From this Newn-N paradigm we have learned a new
universal path that can be made to work Everywhere:

  VIA WIDE2-2 

This universal path is Traceable everywhere and generates 
NO DUPES and is enforcable in most areas and all using
existing hardware and firmware!  It can work in all four
types of APRS Areas:

- In full WIDEn-N areas
- In enforced WIDE2-2 areas
- In enforced 1  hop areas
- Via any in-fill RELAY digi (one hop)

Here is how to set up each of those areas:

In WIDEn-N Areas:
* Digis move WIDEn-N support to UITRACE WIDE, 30
  This supports any N including 2-2 but makes all such
  paths arrive with the point-of-entry identified.  The ALIASES
  of RELAY and WIDE are supported if not abused.
  UIFLOOD can support long linear RELAY,##LNKn-N.

In enforced WIDE2-2 AREAS of modest density:
* Digis add WIDE3-3 and WIDE4-4 to their callsign substitution
  ALIAS list to force those to 1 hop.  Other large n-N's above 4 
  are not supported at all.
  Now, carefully set  UITRACE WIDE2, 30 which enforces only
  two hop use of WIDEn-N.  Only WIDE2-2 or 2-1 is supported
  RELAY and WIDE are still supported unless abused.
  

In enforced 1 hop areas (Big Citys):
* Big High Digis support no n-N routing.  But they do
  have WIDE2-2 , RELAY and WIDE in their callsign substitution
   ALIAS lists.  This enforces 1 hop only and ignores all other
  WIDEn-N coming in from outside.

Local fill-in RELAY-ONLY digis can add WIDE2-2 as an
additional alias.  This gives a nearby WIDE2-2 mobile
at least one hop.

A side advantage of this is that it can be used universally back
east where not all the digis are WIDEn-N capable in the first
place.  In the east, many early HIGH digis were PacComm 
callsign substitution only and could not support WIDEn-N,
thus RELAY,WIDE remains in use and this generates  LOTS
of dupes, whereas a WIDEn-N packet generates none.
But we can finally change that.

PacComm Trace-only digis can simply add "WIDE2-2" to their
alias list, so they can support it.  It only digipeats one hop
since the WIDE2-2 is replaced with the digis call, but since 
most of these digis are well placed, one hop is usually adequate
to get the packet to an IGate.

EVEN old WIDE-ONLY digis can support WIDE2-2.  They
also will only do one hop as the packet will be digipeated
as WIDE2-2* and can go no further.  This also eliminates
ping-ponging WIDES...

CONCLUSION:  A universal WIDE2-2 can work everywhere.
It works in WIDEn-N wilderness areas and still works in enforced
2-2 areas and in enforced 1 hop areas.  It also can be supported
to 1-hop by in-fill RELAY only digis.  Further WIDE3-3 and 4-4 
can at least get 1 hop in  enforced 2 hop areas too.

Lastly, WIDE2-2 is traceable to the first digi in all cases above.
This eliminates the need for RELAY,WIDEn-N or WIDE,WIDEn-N
which are known to cause multiple dupes everywhere.

I think this is the ultimate solution for APRS for simplicity and
easy of guidance to operators.

de WB4APR, Bob