[aprssig] ax25 v 2.2

[J. Lance Cotton]

Remember that the limit isn't a "two-hop" limit, but a 2-digi limit.
If your packet digi path is:

WIDE4-4, then you have 1 digi, but get 4 hops (yes, more than 4 actual
packets since APRS packets propogate outward with multiple digis).

I'm not certain, but the 2-digi limit appears to be a push to limit
source routing and let the digis decide how to route. Don't know how
many digis do this, certainly no APRS digis. It would seem to be in
the frame of mind of real "networks" of digis, like the networks of
the Internet, with router configuration protocols, etc.

-Lance KJ5O

On Fri, 14 Jan 2005 12:36:08 -0500, Robert Bruninga <bruninga at usna.edu> wrote:
> >AX25 version 2.2 limits the number of digipeaters to 2.
> >Has anyone implemented 2.2?  What effect would the
> >2  digipeater limit have on APRS?
> 
> The people who are writing 2.2 do not seem to recognize
>  APRS or other forms of UI communications.  We agree
> completely that more than 2 hops for connected protocol
> is not wortth trying on a typical shared channel.  But
> the SPEC should not be used to try to overcome dumb
> uses of the hardware.
> 
> I can imagine several scenarios where multiple level 2 hops
> over 2 may be useful and may be quite reliable.  Yes, these
> scenarious are RARE and unusual, but the spec should
> allow them!
> 
> Further, although APRS works best at about 2 hops in very
> dense areas of 60 to 100 stations, it can easily use more hops
> in many low density applications.  Again, the hardware and firmware
> of a TNC should allow greater hops for RARE or unusual
> applications.  Besides one-way UI packets like APRS are
> about equally reliable over FOUR hops as a connected
> packet is at 2 hops.  THus if these spec writers are hard
> set on a 2 hop limit for connected protocol, then they
> must allow a 4 hop UI as a minimum equivalent limit for UI..
> 
> Who do we get this common sense to?
> de Wb4APR, Bob
> 
> 
> Mike
> 
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-- 
J. Lance Cotton, KJ5O
joe at lightnigflash.net
http://kj5o.lightningflash.net
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