DMR Rewrite Rules

Contents:

Introduction
What are Rewrite Rules?
The dmrgateway file
DMR Network 1 Stanza
The 2,9,2,9,1 Rule
The Simplex Hotspot
Example One - Accessing VKDMR via FreeDMR Server
Example Two - More use of Statics
References

Introduction

This is a discussion about Rewrite Rules as it applies to FreeDMR. It is a key part of the DMRGateway which is only a part of a much larger subject on configuration of the Multi Mode Digital Voice Modem (MMDVM) application. The MMDVM firmware was developed by Jonthan Naylor G4KLX. A history of the MMDVM's development by Glenn VK4NGA can be found here: The MMDVM Story

I place considerable importance on open system. The source code for the MMDVM firmware can be found here: https://github.com/g4klx. This is the firmware code that runs on the MMDVM board that sits on top of the Raspberry Pi and talks to it through the GPIO's via a simple serial port. Most interface to this board via Pi-Star or similar applications running on the Raspbery Pi or other ARM processor.

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What are Rewrite Rules?

Are you confused about TG and TS and how they magically swap around? If you watch the FreeDMR dashboard you will see that while you are transmitting on TS 2, some stations will receive you on TS2 while others on TS 1. Even TG can magically swap. You can transmit on TG9 and come out on TG5050 on the network and therefore other repeaters, but still be on TG9 on your local repeater.

All this is done, transparently by the Rewrite Rules. They are condigured on Hotspots, MMDVM Repeaters, and Servers.

Here is a description of Rewrite Rules in Jonthan Naylor's own words:
"This software [DMR Gateway] works by use of powerful rewriting rules which allow for changes in the slot, talk group, the type, and even the destination, of the messages. Without a rewrite rule, even if it does no actual rewriting, traffic will not be passed through from that defined network to the MMDVM and back again."
Source:https://github.com/g4klx/DMRGateway#readme

Rewrire Rules are defined thus:
TGRewrite=fromSlot,fromTG,toSlot,toTG,range
TypeRewrite=fromSlot,fromId,toSlot,toId The Rewrite Rules can be found in Pi-Star applicatio in the /etc/dmrgateway file.

A full explaination of Rewrite Rules can be fornd here: https://github.com/g4klx/DMRGateway/wiki/Rewrite-Rules

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The dmrgateway file

The /etc/dmrgateway and can be accessed directly on the Raspbery Pi or via the Pi-Star menu:
Configuration-->Expert mode-->full edit DMG GW
Select the menu under the full editor as the top line menu is in GUI form, where as the full editor show in textual form.

As an example, this is a copy of the dmrgateway from my simplex hotspot:

[General]
RptAddress=127.0.0.1
RptPort=62032
LocalAddress=127.0.0.1
LocalPort=62031
RuleTrace=0
Daemon=1
Debug=0
RFTimeout=20
NetTimeout=20

[Log]
DisplayLevel=0
FileLevel=1
FilePath=/var/log/pi-star
FileRoot=DMRGateway

[Voice]
Enabled=1
Language=en_GB
Directory=/usr/local/etc/DMR_Audio

[Info]
Enabled=0
RXFrequency=439150000
TXFrequency=439150000
Power=1
Latitude=-27.64221
Longitude=153.41346
Height=0
Location="Brisbane, QG62qi"
Description="Australia"
URL=https://www.qrz.com/db/VK4PK

[XLX Network]
Startup=950
Enabled=0
File=/usr/local/etc/XLXHosts.txt
Port=62030
Password=passw0rd
ReloadTime=60
Slot=2
TG=6
Base=64000..
Relink=60
Debug=0
Id=505xxxx
UserControl=1

[DMR Network 1]
Enabled=0
Address=87.117.229.173
Port=62031
TGRewrite0=2,9,2,9,1
PCRewrite0=2,94000,2,4000,1001
TypeRewrite0=2,9990,2,9990
SrcRewrite0=2,4000,2,9,1001
PassAllPC0=1
PassAllTG0=1
PassAllPC1=2
PassAllTG1=2
Password="passw1rd"
Debug=0
Location=1

[DMR Network 2]
Enabled=0
Address=217.147.81.22
Port=55555
TGRewrite0=2,8,2,9,1
PCRewrite0=2,84000,2,4000,1001
Password="PASSWORD"
Debug=0
Id=1234567
Location=0
Options="TS1=505;DIAL=0;VOICE=1;LANG=en_GB;SINGLE=1;TIMER=10;"

[DMR Network 3]
Enabled=0
Name=HBLink
Address=1.2.3.4
Port=5555
TGRewrite=2,11,2,11,1
Password="PASSWORD"
Location=0
Debug=0
TGRewrite0=2,11,2,11,1

[GPSD]
Enable=0
Address=127.0.0.1
Port=2947

[APRS]
Enable=1
Address=127.0.0.1
Port=8673
Description=APRS for DMRGateway
Suffix=DMR

[Dynamic TG Control]
Enabled=1
Port=3769

It contains eleven stanzas. Of particular interest are the three DMR Network stanzas.

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DMR Network 1 Stanza

[DMR Network 1]

Parameter	value	Function	Comment
Enabled	1	Enabled for use
Address	87.117.229.173	ldp see Label_Distribution_Protocol
Port	62031	Port in use
TGRewrite0	2,9,2,9,1	fromSlot,fromTG,toSlot,toTG,range	Translates one talk group ID to another, and to alter the time slot
PCRewrite0	2,94000,2,4000,1001	fromSlot,fromID,toSlot,toID,range	Same as TGRewrite but only operates on private calls
TypeRewrite0	2,9990,2,9990	fromSlot,fromID,toSlot,toID	Maps a group call to a private call.
SrcRewrite0	2,4000,2,9,1001	fromSlot,fromID,toSlot,toTG,range	Rewrite the source/from Talk Group ID to another ID
PassAllPC0	1	PassAllPC=Slot	Passes all private calls without rules
PassAllTG0	1	PassAllTG=Slot	Passes all talk groups without rules
PassAllPC1	2	ditto
PassAllTG1	2	ditto
Password	"passw1rd"	Password to access this network
Debug	0	Set the Debug Level
Location	1

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The 2,9,2,9,1 Rule

Why have a rules that says On TS2 TG9 send my traffic to TS2 TG9?
The reason is thhat NO traffic is sent without a rule.

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The Simplex Hotspot

Rewrite Rules are essencial to the operation of the simplex hotspot as as a simplex hotspot only one transmitter dedicated TS2. There is no TS1. The hotspot only sends TS2. Assignment of talk groups to time slots is something done at the repeater/hotspot level and does not propagate beyond that level (just as "color code" is only used between your radio and the hotspot/repeater).

Only the talk group number has meaning to the master servers. ---- IS THIS TRUE?

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Example One - Accessing VKDMR via FreeDMR Server

In this example a "Rewrite Rules" using FreeDMR directly and not though DMRGateway.

All VKDMR talkgroups are entered as static.

Color Code:

Magenta is the default for Dial a Talkgroup from UK and seems to work fine testing about 10 WW talkgroups
Blue is to let Group Call 9990 Echo Pass
Yellow shows what is static on slot 1
Green shows what the default Dial a TG is set as

# DMR+_IPSC2-Australia, VKDMR Network
[DMR Network 2]
Enabled=1
Address=103.93.139.189
Port=55555
TGRewrite=2,8,2,9,1
TGRewrite=2,505,2,505,1
TGRewrite=1,3801,1,3801,9
TGRewrite=2,9990,2,9990,1
TGRewrite=1,3809,1,3809,1
TGRewrite=1,3810,1,3810,1
TGRewrite=1,1,1,1,1
TGRewrite=1,3,1,3,1
TGRewrite=1,8,1,8,1
TGRewrite=1,5,1,5,1
TGRewrite=1,13,1,13,1
TGRewrite=1,113,1,113,1
TGRewrite=1,123,1,123,1
TGRewrite=1,310,1,310,1
TGRewrite=1,133,1,133,1
TGRewrite=1,153,1,153,1
Password=PASSWORD
Debug=0
Id=505xxx
Name=DMR+_IPSC2-Australia
Options="TS2_1=505"

# Australia-3 ID-5053 Open Bridge Server, VK4RDB, Mt Cotton, Brisbane
[DMR Network 3]
Enabled=1
Name=FreeDMR Australia
Address=hot.vkfreedmr.org
Port=62031
TypeRewrite=2,80,2,80,9909
TypeRewrite=2,9991,2,9991,16767223
TGRewrite=2,9,2,9,1
TGRewrite=1,9990,1,9990,1
TGRewrite=1,505,1,505,1 # Radios should add as channel on Slot 1
TGReWrite=1,5050,1,5050,1
PassAllPC=1
PassAllPC=2
Password=passw0rd
Debug=0
Id=505xxx
# Options=”TS1=505,5050;DIAL=530;TIMER=10;VOICE=0;”
Location=0

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Example Two - More use of Statics

# DMR+_IPSC2-Australia, VKDMR Network
[DMR Network 2]

Enabled=1
Address=43.245.72.66
Port=55555
TGRewrite=2,8,2,9,1
TGRewrite=1,3801,1,3801,1
TGRewrite=1,3802,1,3802,1
TGRewrite=1,3803,1,3803,1
TGRewrite=1,3804,1,3804,1
TGRewrite=1,3805,1,3805,1
TGRewrite=1,3806,1,3806,1
TGRewrite=1,3807,1,3807,1
TGRewrite=1,3808,1,3808,1
TGRewrite=1,3809,1,3809,1
TGRewrite=1,3810,1,3810,1
TGRewrite=1,1,1,1,1
TGRewrite=1,3,1,3,1
TGRewrite=1,5,1,5,1
TGRewrite=1,8,1,8,1
TGRewrite=1,13,1,13,1
TGRewrite=1,30,1,30,1
TGRewrite=1,53,1,53,1
TGRewrite=1,80,1,80,1
TGRewrite=1,113,1,113,1
TGRewrite=1,123,1,123,1
TGRewrite=1,133,1,133,1
TGRewrite=1,143,1,143,1
TGRewrite=1,153,1,153,1
TGRewrite=1,310,1,310,1
TGRewrite=1,320,1,320,1
TGRewrite=1,321,1,321,1
TGRewrite=2,505,2,505,1
TGRewrite=1,530,1,530,1
TGRewrite=1,1911,1,1911,1
TGRewrite=1,2351,1,2351,1
TGRewrite=1,3117,1,3117,1
TGRewrite=1,3155,1,3155,1
TGRewrite=1,3167,1,3167,1
TGRewrite=1,3191,1,3191,1
TGRewrite=1,3199,1,3199,1
TGRewrite=1,8406,1,8406,1
TGRewrite=1,8409,1,8409,1
TGRewrite=1,8454,1,8454,1
TGRewrite=1,8509,1,8509,1
TGRewrite=1,8540,1,8540,1
TGRewrite=1,8555,1,8555,1
Password="PASSWORD"
Debug=0
Id=505xxx
Location=0
Name=DMR+_IPSC2-Australia
Options="StartRef=4000;RelinkTime=15;UserLink=1;TS1_1=9;TS2_1=505;"

# Australia-3 ID-5053 Open Bridge Server, VK4RDB, Mt Cotton, Brisbane
[DMR Network 3]
Enabled=1
Name=FreeDMR Australia
Address=hot.vkfreedmr.org
Port=62031
TypeRewrite=2,80,2,80,9909
TypeRewrite=2,9991,2,9991,16767223
TGRewrite=2,9,2,9,1
TGRewrite=1,9990,1,9990,1
TGRewrite=2,9990,2,9990,1
TGRewrite=1,302,1,302,1
TGRewrite=1,505,1,505,1
TGRewrite=1,913,1,913,1
TGRewrite=1,969,1,969,1
TGRewrite=1,970,1,970,1
TGRewrite=1,973,1,973,1
TGRewrite=1,2350,1,2350,1
TGRewrite=1,3100,1,3100,1
TGRewrite=1,5050,1,5050,1
TGRewrite=1,5052,1,5052,1
TGRewrite=1,5055,1,5055,1
TGRewrite=1,5056,1,5056,1
TGRewrite=1,50599,1,50599,1
TGRewrite=1,50510,1,50510,1
TGRewrite=1,50595,1,50595,1
TGRewrite=1,50556,1,50556,1
PassAllPC=1
PassAllPC=2
Password=passw0rd
Debug=0
Id=505xxx
Options=”TS1=505,5050;DIAL=530;TIMER=10;VOICE=0;”
Location=0

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References

https://tgifnetwork.createaforum.com/new-board/the-pi-star-gateway-function-demystified/

https://forum.pistar.uk/viewtopic.php?f=5&t=2287#p11311https://forum.pistar.uk/viewtopic.php?f=5&t=2730

https://forum.pistar.uk/viewtopic.php?f=5&t=2730

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Glenn Lyons VK4PK
glenn@LyonsComputer.com.au
Ver:gnl20230310 - pre published v0.9