APRS Digipeatersoftware DIGI_NED
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Alter the digipeater list

Be very careful if you use more than one option to specify how frames will be repeated between a given pair of switch ports.

Digipeat

Repeat a frame if we are next in the digipeater list. Use "Digipeat:".

Assume we select on a digipeater field of WIDE.
For incoming frame: A>B,C,D*,TRACE,E,F

will do normal digipeating, aliases are replaced by the DIGI_CALL.
e.g. gives: A>B,C,D,DIGI_CALL*,E,F

"Add" will do normal digipeating and add new digipeaters at the end of the digipeater list
e.g. Add X,Y gives: A>B,C,D,DIGI_CALL*,E,F,X,Y

"Replace" will do normal digipeating and replace the not yet used digipeaters with a new list of digipeaters.
e.g. Replace DIGI_CALL,X,Y gives: A>B,C,D,DIGI_CALL*,X,Y

"New" will replace the whole digipeater list with a new one. The DIGI_CALL is put first in the list
e.g. New DIGI_CALL,X,Y gives: A>B,DIGI_CALL*,X,Y

"Swap" will replace the digipeater call that was supposed to handle the packet with a new callsigns. The first callsign will be the 'sender'
(note that with this operation you can avoid callsign substitution with the DIGI_CALL call)
e.g. Swap RELAY,X,Y gives: A>B,C,D,RELAY*,X,Y,E,F

"Hijack" removes the previous digipeater call from the list and will then perform the "Swap" operation. If there is no previous digipeater then it will behave like Swap does (note that with this operation you can avoid callsign substitution with the DIGI_CALL call)

"Erase" removes all digipeater calls from the digipeater list.

"Keep" will keep the digipeater list unchanged, with a number you can specify how many digipeaters should be marked as "used"
e.g. Keep gives: A>B,C,D,TRACE*,E,F
Keep0 gives: A>B,C,D*,TRACE,E,F (i.e. unchanged path)

"Shift" will remove all "used" digis except the last used one and replace the unused digi in the digi list with new calls of the digipeater list.
e.g. Shift DIGI_CALL,X,Y gives: A>B,D,DIGI_CALL*,X,Y

All the operations can take an optional number to specify how many digipeater calls shall be marked as "used" by the DIGI_NED. Default is 1, but you can specify a number from 0 to 8. With 0 no digipeater call is used up (used for WIDEn-N digipeating), with 8 all digipeater calls are used up. The value 2 is used for the last hop on TRACEn-N digipeating, both the own call and the remaining TRACEn shall be marked as used on this last hop.

For incoming frame: A>B,C,D*,WIDE4-3,E,F
e.g. Swap0 WIDE4-2 gives: A>B,C,D*,WIDE4-2,E,F

For incoming frame: A>B,C,D*,TRACE4-1,E,F
e.g. Swap2 DIGI_CALL,TRACE4 gives: A>B,C,D,DIGI_CALL,TRACE4*,E,F

DigiTo

"DigiTo:" is used to repeat a frame if it has a desired TO field. It is only evaluated when there are no digipeaters at all in the path. This is useful for picking up packets that usually have no digis on them at all. Some settings are CQ, ID and BEACON.

Assume we select on a to field of ID.
For incoming frame: A>ID Add X,Y gives: A>ID,X,Y

There is something special about "DigiTo:". "DigiTo:" supports destination-call SSID replacement used for intelligent digipeating on destination-call SSID. For incoming frame: A>ID-3 and replacement SSID '2' the output will be A>ID-2

"DigiTo:" does not add DIGI_CALL automatically, you have to add this yourself if you want it. It is possible to use "Add", "Replace", "New", "Swap", "Hijack", "Erase" and "Keep" operations. If you don't want the packet to digipeat on SSID set the destination call SSID to 0 to avoid problems and miss interpretation.

DigiSsid

"DigiSsid:" is used to repeat a frame if it has a desired TO field just like "DigiTo:". It is only evaluated when there only unused digipeaters in the path. This is useful for implementing SSID digipeating the correct way. Just like "DigiTo:" this rule can change the SSID.

"DigiSsid:" does not add DIGI_CALL automatically, you have to add this yourself if you want it. It is possible to use "Add", "Replace", "New", "Swap", "Hijack", "Erase" and "Keep" operations. If you don't want the packet to digipeat on SSID set the destination call SSID to 0 to avoid problems and miss interpretation.

If a "DigiSsid:" rule hits the "Digipeat:" rules will not be executed, the "DigiSsid:" has a higher priority.

Block

With "Block:" you can define FROM callsigns that should not be repeated. This is for calls like MYCALL, N0CALL etc. or misbehaving Hams...

Note that the node callsign replaces any alias or callsign used to digipeat, or is added into the digipeater list as required to allow DIGI to detect potential digipeat loops. e.g. (WIDE,WIDE,WIDE)

Yes, DIGI_NED does callsign swapping, and wont repeat its own packet. With the more advanced rules you can make rules without callsign swapping. To prevent loops DIGI_NED remembers the CRC of recently send packets. The parameter "keep_time" defines how long it takes until DIGI_NED forgets the CRC. There are special measures of "short_keep_time" and a filter to remember certain types of data for a shorter period (i.e. messages which are repeated).

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