APRS Digipeatersoftware DIGI_NED
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Black-hole coverage


In the new aproach for the paradigm routing algorthm black-hole of fill-in digi's play a important role. Use fill in digi's as proposed in the paradigm routing algorthm.


A digipeater in the APRS network can come and go. Problems arise when too many non-intelligent digipeaters are in a small area. This can easily happen in cities because of the dense population and lots of inadequately covered areas that appear in such areas due to buildings. These building blocks direct access to the nearest WIDE.

A station in such a 'black-hole' needs in that case a digipeater in the neighborhood which will convey signals from the station to the WIDE and which digipeats signals from the WIDE to the station.

Signals from the WIDE which are repeated by the "gap-fill" digipeater do not need to be digipeated once more by other digipeaters; those other digipeaters can pickup those signals already directly from the WIDE. The signals from the local station however should be digipeated; at least by the WIDE!

With DIGI_NED a port can be assigned 'local:'. Data that is send directly to the digipeater will be digipeated normally on a local port; there is no difference with non-local ports. Data which is not directly send to DIGI_NED but first passed through another digipeater, for example the aforementioned WIDE, will on the local port be transmitted with a truncated "via" list; digipeaters in the "via" list which are not "used" yet are removed. This way another digipeater will not handle the digipeated data anymore.

For intelligent digipeaters this is not really needed; data from the WIDE will also been received by the other digipeaters in the neighborhood and when a digipeater retransmits the messages than those other repeaters will not respond because the data has already been handled before. When digipeaters in the area are however not intelligent than they would just digipeat the data once more. This will result in a lot of needless traffic. In that case the port of DIGI_NED on which the data is transmitted can be assigned "local:" so there are no digipeater calls left anymore on which surrounding dumb digipeaters could react.

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