[aprssig] ID requirements...

Wes Johnston aprs at kd4rdb.com
Mon Nov 8 20:32:35 EST 2004

This is all well and good, but WHY does a digipeater need to ID past one hop?

I say this perhaps to make us stop and think (collectively as a group).

A digipeater does two things:
1) extends coverage in a local area
2) brings in traffic from distant areas to my local area.

Now to answer #1, yes the local users need to know the digipeater exists.  It is
nice that they know what part of town it's in so that they can adjust their
equipment to get to it better.

The answer to #2 is that people in distant areas do NOT need to know about my
local digi.  They will not be sending messages to it... they send messages to
my APRS client.  There are cases where someone will want to direct traffic
along a very specific path thru specific digipeaters, but really who does that?
 The problem is that so few of the digipeaters do pre-emptive digipeating, and
if they don't hear packets in the right order they won't digipeat traffic.  For
example:  I send out a packet which is RELAY,K9PUP,K9DOG,K9CAT. It makes it as
far RELAY*, but k9pup doesn't hear it due to a collision.  K9DOG may have heard
the packet because the band was open, but didn't digipeat it becuase it didn't
look like RELAY*,K9PUP*,K9DOG. And what happens when one of my SPECIFIC
digipeaters fails?

On a practical side, we know the ENTRY point into the network of some distant
station we are trying to message, but we never know the number of hops our
message will take to get there... so a path like RELAY,WIDE2-2,K9CAT has no
practical benefit... we may as well just send a packet to RELAY,WIDE3-3.

I guess I'm just on a rant... but really, why do I need to know about a network
resource that I cannot (practically) specifically address to get to a station
I'm interesting in coresponding with, and why would I want to send a message to
a digipeater when there is no person manning it?

To me "advertising" your local digipeater out 2 or 3 hops is just a ego thing.


Quoting "Brian B. Riley User" <brianbr at mac.com>:

> On 11/8/04 6:20 PM, "Robert Bruninga" <bruninga at usna.edu> wrote:
> > You are right that that will cause dupes on the hour and half hour.
> > Therefore I would do it this way:
> > #1 every 30 mins starting at   0
> > #2 every 30 mins starting at 10
> > #3 every 60 mins starting at 30
> >
> > That will get you a local packet every 20 mins, a WIDE
> > every 30, and a WIDE2-2 every hour and no dupes.
> > ***But once every hour on the 50 minute mark, you wont
> > get any.   But 5 out of 6 ain't bad, since the rest of it works
> > so well.
> It should be
>     #1 every 30 mins starting at   0
>     #2 every 30 mins starting at 10
>     #3 every 60 mins starting at 20
>   That covers 0,30,10,40,20 and leaves out 50
> --
> Cheers ... 73 de brian, n1bq, underhill center, vermont
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