[aprssig] The Current Meaning of WIDEn-N

Robert Bruninga bruninga at usna.edu
Mon May 19 09:46:10 CDT 2014


Paragraphs as marked:

> What is the CURRENT meaning of the first n in WIDEn-N?

Same as it has always been.  The number of hops that the sender intended
(the number is not acted on).  It goes along for the ride to show what the
original packet started with.

Next Paragraph TRUE:

>Originally, WIDEn-N replaced repeated WIDE,WIDE,WIDE, yielding a much
shorter routing path that allowed each digipeater to decrement the second
number until it reached zero instead of marking another WIDE alias as
used. Therefore, an incoming packet with a route of WIDE3-1 would indicate
that the originating station requested three hops and there is one
remaining. This was important at this point since TRACE was still a
separate concept and without an originating request number, you wouldn't
know how far the packet has already gone.

> This left us still with the non-"n-N" RELAY alias, so a typical path
would look like "RELAY,WIDE2-2" Due to a bug (omission?) in a major
digipeater firmware revision, they did not perform duplicate suppression
between these two aliases (any two aliases? any non-n-N aliases?).

(the packet via RELAY and the packet via any other following alias)

Next paragraph mostly TRUE:

The solution was to dedicate the alias WIDE1-1 to replace RELAY, which
leaves us with the issue that there is no "proper" way to express a single
WIDE hop correctly. This was solved by "pre-consuming" the first hop in a
two hop request and start packets with WIDE2-1. As far as I can tell, this
brings us to the present, where low level digis respond to WIDE1-1 and
high level routing paths start as either WIDE2-1, WIDE2-2 or WIDE3-3.

The reason for RELAY and its modern WIDE1-1 was to have an alias that
would allow ANY OLD TNC (going back 30 years) to still be able to serve as
a "first hop" digi, without requiring special firmware to recongnize the
WIDEn-N and special decrementing function.  WIDE1-1 is simply a literal
ALIAS that any DIGI can be set to act on, including both OLD ones and new
WIDEn-N ones.

> my Elmers. They had explained it that WIDE1-N was requesting hops from
"level 1"
or low level digis. WIDE2-N was then requesting "level 2" hops through
higher level digis, and so on.

True, but not because of the 1 or the 2.

> so the need for knowing how far a packet has already gone can now be met
by the fact that every well behaving digi should trace on every packet (I
think?). The "originally requested hop count" value is redundant, and
meaningless since we're promoting originating paths like
"WIDE1-1,WIDE2-1."

It is now 10 years later and still a large percentage of existing
digipeaters have NEVER changed from the original 20 year old settings.

> Another change since the original deprecation of RELAY is the
development of the idea of preemptive digipeating... It seems like this
concept in addition to distinct aliases for high and low level digis would
be useful for the network; particularly so in places like California where
I'm doing my testing.  When my mobile path of "WIDE1-1,WIDE2-1" reaches an
8000' high WIDE digi directly, it only consumes the first hop and I'm left
requesting a second hop from the next ring of California digis 150 miles
out.

In SoCal and anywhere else that APRS is saturated, every such
high-level-digi should be set to NOT honor any hops beyond one.  IN that
sense, it ignores the WIDEn-N protocol and simply has a list of literal
aliases it will honor once and only once.  Usually that list contains the
literals WIDE1-1, WIDE2-2, WIDE3-3 and WIDE4-4.  All of those will be
digipeated once, and marked as used.  The packet goes no farther.

>When I change my path to a single WIDE2-1 or WIDE1-1 (I don't know which
is correct), I can finally stay within my ALOHA circle but the low level
digis in places like San Luis Obispo county (tight hilly areas with very
deep valleys) consume my single hop and I'm never repeated by the high
level digis and heard beyond 3-5 miles.

They don't "consume it" they act on it.  If any high level digi hears your
packet direct, it too will act on it, in other words, the fact that a
local digi also heard a packet, does not in anyway impact its ability to
also be heard and acted on by a high level digi that also hears it.

> Even if the low level digis only responded to WIDE1-1 (a behavior which
I don't see), this leaves me with the dilemma of either requesting WIDE1-1
and having my hops consumed by low-level digis,
WIDE2-1 and never get digipeated by low digis so 80-90% of my traffic is
lost in valleys, or WIDE1-1,WIDE2-1 and intermittently show up 200 miles
away.

Use the path of WIDE1-1, WIDE2-1.  If the sysops of the area do not want 2
hop digipeating from the high level digis, they are supposed to not
support WIDE2-1 as I noted above.  This lets you drive between the
different areas and be supported or not, depending on the settings of the
local digi owners in that area.

>Furthermore, analysis of bulk APRS traffic from APRS-IS is showing 850ppm
of packets being Igated with paths containing hops such as
WIDE1-2 or WIDE2-3, which are complete non-sense according to any of the
official meanings for WIDEn-N.

Yes, those are folks maybe tyring to cheat the system, or cluless about
how APRS operates.

> or am I seeing evidence of confusion on the part of users?

Probably the later.

Bob, Wb4APR

--
Kenneth Finnegan, W6KWF
http://blog.thelifeofkenneth.com/
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