Ports and endpoints

Every UDP port and who sends to it, rendered from a3-osc.json (truth). Other pages name a port by its listener (core.osc, motion.vu, …).

Hosts

Named in hosts; see the listener table. On the rig A³ Motion runs on the Core, hence 127.0.0.1; on its own machine (hardware) that machine’s address replaces it.

Cabling

The Core has two network sockets, each on a network of its own:

router 192.168.8.1 ───── eno1    A³ Core 192.168.8.10/24    control network
A³ Mixer 192.168.8.11 ── router or switch, same network

StemDeck machine ─────── enp5s0  A³ Core 192.168.9.10/24    audio network (AES67, PTP)

First socket (eno1): the Core’s address, the gateway and the DNS server (192.168.8.1), file 10-a3.network. OSC, the web window and the desk run here. The A³ Mixer reaches the Core over this network through the switch or router; the Core no longer sits between them.
Second socket (enp5s0, optional): the audio network, file 20-a3-aes67.network. Its own subnet 192.168.9.0/24, Core 192.168.9.10/24, no gateway and no DNS: the only way out is the first socket, and a reply always leaves by the socket it came in on.
There is no br0 bridge and no spanning tree any more (until 2026-10-14 the second socket was bridged with the first); a cable drop on one socket does not touch the other.
Written by the package (install); an upgrade retires the old bridge files.

The audio network: AES67 and PTP

Audio between machines runs on the second socket, apart from OSC:

What	Detail
Socket, subnet	the second socket, `192.168.9.0/24`, Core `192.168.9.10/24`
Clock	PTP: `ptp4l` on the second socket, the Core as master unless a better clock is on the network
Core sends	12 channels, stream `AES67 <hostname> out`, 44.1 kHz, 24 bit, packet time 0.5 ms, multicast (`239.69.150.243`, port 5004)
Announcement	SAP on `239.255.255.255`, port 9875; receivers find the stream by its name
Who drives the stream	the audio interface: the samples leave unconverted and the engine is never pulled onto the PTP clock
Deck streams	one per deck, sent by the machine that runs the deck: 41 channels (MAIN1–16, AUX1–16, CUE1–9), stream `AES67 deck <X>`, 44.1 kHz, 24 bit, packet time 0.25 ms (1393 bytes on the wire, so every packet fits a 1500-byte frame), multicast, one group per deck (`239.69.150.244` deck A, `.245` deck B), port 5004
Receive rule	the Core receives deck streams outside the PTP clock: the sound card stays the Core’s clock and the stream is resampled into it, so a deck stream never pulls the engine. The receiver needs an MTU of 1500
Deck host	a machine that runs a deck (a3nuc2 for deck B today; C and D can run on any deck host, one letter per host) runs its own sender, unit `a3-aes67-deck@<X>`, which the StemDeck package ships. The sender needs the package’s base unit `stemdeck-aes67.service` (PTP client and receiver), which stays off where a3-core’s own AES67 unit exists, and the audio socket from `STEMDECK_AUDIO_PORT`; the installer’s deck-host role sets both up (StemDeck). The sender sends unconverted. It also receives the Core’s stream, channels 1 and 2 of which are the REC bus
Latency	a deck on another machine arrives about 18 ms later than a local one (calculated, not measured). StemDeck’s path latency setting (StemDeck) makes up for it

EEE is off on the audio socket of every machine that has one, a deck host included: with it on the link drops every minute or two.

PTP and the AES67 sender start only when a second socket is configured (audio-port); without one the Core has neither and uses one network. The streams are audio, not OSC, so they are not in the port tables below. Unit: a3-aes67; the engine’s JACK links: I/O map.

Ports, by listener

Rendered: edit a3-osc.json, not this. core.web also serves GET /api/truth. devices.announce is where Core broadcasts /core/here every 2 s for the devices that follow it. Host any (0.0.0.0): every interface; local: this machine only.

Program	Role	Host	Port	Carries
core	osc	any (0.0.0.0)	9000	every controller’s messages, and /beat from the analyzer
core	vu-relay	local (127.0.0.1)	9003	the engine’s and StemDeck’s /vu bundles, forwarded unchanged to Motion, the mixer, radla, the remote Motion followed and every desk followed
core	web	any (0.0.0.0)	9080	the traffic window (HTTP, not OSC); every interface, decided 2026-09-30
motion	osc	any (0.0.0.0)	7771	Core’s relays (StemDeck’s preview among them), /beat
motion	vu	any (0.0.0.0)	7772	Core’s /vu bundles (the engine’s meters, forwarded)
motion	energy	any (0.0.0.0)	7777	the IEM EnergyVisualizer’s /EnergyVisualizer/RMS
stemdeck	osc	any (0.0.0.0)	7780	Core’s bus switches and its request for all of them; a one-deck instance k (–deck A..D) listens on this port + (k - 1): A 7780, B 7781, C 7782, D 7783 (Core’s deck relay sends deck k there); the two-deck StemDeck keeps 7780
devices	announce	any (0.0.0.0)	7790	Core’s /core/here broadcast: where every device fetches the truth
mixer	osc	mixer (192.168.8.11)	7772	Core’s relays and lamps, /beat, /vu
desk	osc	any (0.0.0.0)	7773	Core’s relays, lamps and stems, /beat – every virtual desk Core follows (four at most)
desk	vu	any (0.0.0.0)	7774	the engine’s and StemDeck’s /vu bundles, forwarded unchanged by Core (core.vu-relay)
beat-analyzer	clock	any (0.0.0.0)	7775	/tap, /clockmode, and /beat from Motion in clock mode 0
engine	control	local (127.0.0.1)	9005	the a3-core window’s view of the engine (HTTP JSON, loopback only; not OSC)
update	control	any (0.0.0.0)	9081	a3-update on every machine: Core asks for its packages and for an update to a release (HTTP JSON, only from the core host; not OSC)
engine	osc	local (127.0.0.1)	9004	a3-engine: Core’s words in engine mode – channel.gain/eq./volume/3d/filter.frequency/filter.q/aux-send/cue/filter/azimuth/elevation/source, filter.frequency/resonance/mode, master., aux-return.cue, delay.bpm, aux-return.delay.*, engine.open
x11vnc	vnc	any (0.0.0.0)	5901	the Core’s screen (VNC, not OSC)
screencast	stream	any (0.0.0.0)	9930	the screen’s picture as MPEG-TS, several viewers on one encode (OBS, the pro-DJ apps) (listener, not OSC)
radla	osc	radla (192.168.43.96)	9000	/beat
radla	vu	radla (192.168.43.96)	9001	/vu
prolink	announce	any (0.0.0.0)	50000	Pro DJ Link keep-alives (broadcast, not OSC)
prolink	beat	any (0.0.0.0)	50001	Pro DJ Link beat packets (broadcast, not OSC)
prolink	status	any (0.0.0.0)	50002	Pro DJ Link status packets (broadcast, not OSC)
aes67	stream	aes67-core (239.69.150.243)	5004	the Core’s 12 channels as AES67 (RTP, L24, 44.1 kHz, 0.5 ms packets), multicast on the audio socket; not OSC
aes67	deck	aes67-deck-{deck} (239.69.150.244, 239.69.150.245)	5004	one deck’s 41 channels: MAIN1-16, AUX1-16, CUE1-9 (L24, 44.1 kHz, ptime 0.25 ms), sess.name “AES67 deck ”; the receiver needs net.mtu = 1500 (the default 1280 truncates the 1365-byte RTP packet); not OSC
aes67	sap	sap (239.255.255.255)	9875	AES67 stream announcements (SAP/SDP), multicast on the audio socket, every sender and receiver; not OSC
ptp4l	event	ptp (224.0.1.129)	319	PTP event messages; the Core is master on the audio socket; not OSC
ptp4l	general	ptp (224.0.1.129)	320	PTP general messages (announce, follow-up); not OSC

Who sends where

The file’s routes, rendered. Carries: the route’s mark (vu: meters), else what the listener takes. Sender iem is the IEM EnergyVisualizer, which no longer runs (see below); prolink: any Pro DJ Link player; StemDeck as master has its own rows.

From	To	Carries
mixer	`core.osc`	every controller’s messages, and /beat from the analyzer
mixer	`beat-analyzer.clock`	/tap, /clockmode, and /beat from Motion in clock mode 0
desk	`core.osc`	every controller’s messages, and /beat from the analyzer
desk	`beat-analyzer.clock`	/tap, /clockmode, and /beat from Motion in clock mode 0
prodj	`core.osc`	every controller’s messages, and /beat from the analyzer
prodj	`beat-analyzer.clock`	/tap, /clockmode, and /beat from Motion in clock mode 0
motion	`core.osc`	every controller’s messages, and /beat from the analyzer
motion	`beat-analyzer.clock`	/tap, /clockmode, and /beat from Motion in clock mode 0
core	`motion.osc`	Core’s relays (StemDeck’s preview among them), /beat
core	`motion.vu`	Core’s /vu bundles (the engine’s meters, forwarded)
core	`mixer.osc`	Core’s relays and lamps, /beat, /vu
core	`desk.osc`	Core’s relays, lamps and stems, /beat – every virtual desk Core follows (four at most)
core	`desk.vu`	vu
core	`mixer.osc`	vu
core	`radla.vu`	/vu
core	`engine.osc`	a3-engine: Core’s words in engine mode – channel.gain/eq./volume/3d/filter.frequency/filter.q/aux-send/cue/filter/azimuth/elevation/source, filter.frequency/resonance/mode, master., aux-return.cue, delay.bpm, aux-return.delay.*, engine.open
core	`update.control`	a3-update on every machine: Core asks for its packages and for an update to a release (HTTP JSON, only from the core host; not OSC)
core	`stemdeck.osc`	Core’s bus switches and its request for all of them; a one-deck instance k (–deck A..D) listens on this port + (k - 1): A 7780, B 7781, C 7782, D 7783 (Core’s deck relay sends deck k there); the two-deck StemDeck keeps 7780
core	`devices.announce`	Core’s /core/here broadcast: where every device fetches the truth
engine	`core.osc`	every controller’s messages, and /beat from the analyzer
engine	`core.vu-relay`	vu
beat-analyzer	`core.osc`	every controller’s messages, and /beat from the analyzer
beat-analyzer	`motion.osc`	Core’s relays (StemDeck’s preview among them), /beat
beat-analyzer	`mixer.osc`	Core’s relays and lamps, /beat, /vu
beat-analyzer	`radla.osc`	/beat
iem	`motion.energy`	the IEM EnergyVisualizer’s /EnergyVisualizer/RMS
stemdeck	`prolink.announce`	Pro DJ Link keep-alives (broadcast, not OSC)
stemdeck	`prolink.status`	Pro DJ Link status packets (broadcast, not OSC)
stemdeck	`prolink.beat`	Pro DJ Link beat packets (broadcast, not OSC)
stemdeck	`core.osc`	every controller’s messages, and /beat from the analyzer
stemdeck	`mixer.osc`	vu
stemdeck	`core.vu-relay`	vu
prolink	`prolink.beat`	Pro DJ Link beat packets (broadcast, not OSC)

Motion’s energy listener has no sender. /EnergyVisualizer/RMS came straight from the EnergyVisualizer plug-in inside REAPER, bypassing Core (aside in the register). REAPER is gone and the engine does not send it, so the listener stays open and nothing arrives (an open issue).
Core has two receive ports: commands on core.osc, meters on core.vu-relay; Motion three (control, 25 Hz meters, 426-float energy frames).
/tap goes straight to the beat-analyzer: timing wants no relay.
radla is off this subnet, via the gateway: beat, meters, network audio.
Read a port with its host: 7772 is both Motion’s and the Mixer’s meter port. A sending port is ephemeral and means nothing.

The numbering, and what would be better

The numbers grew: 7771, 7772, 7775, 7777 have three owners and two gaps; 9000–9005 interleave Core and the engine; no number names its owner. Proposal — the block names the owner:

Block	Owner
`9000–9009`	A³ Core
`9010–9019`	Core’s engine
`7700–7709`	A³ Motion
`7710–7719`	A³ Mixer
`7720–7729`	beat-analyzer

with fixed offsets: +0 control, +1 VU, +2 energy, +5 beat clock.

Not the current state. The devices follow one edit of a3-osc.json, but a half-done renumbering is silent. The tables above are what the rig does today.