ACN

showstack / protocols / acn

Also called Architecture for Control Networks, E1.17, Full ACN.

ESTA's full control network architecture: SDT for reliable sessions over UDP, DMP for device properties, and DDL device descriptions in XML so a controller can drive a device it has never met. sACN borrows only the root layer of this; ACN is the rest of it.

Network transportOpenESTAReported

Stewarded by ESTA (Entertainment Services and Technology Association).

Control Small, urgent, must arrive

Small messages that either repeat constantly or fire once. Bandwidth is almost never the problem.

What kills it. Latency and loss on the messages that fire once. A repeating level survives a dropped packet; a GO does not.

Why this one, and not what the category suggests. The architecture sACN was cut down from. What it carries is lighting control.

The four flows, and why the model is worth having →

Ports

udp/5568 SDT (Session Data Transport)
Registered with IANA in 2006 as "sdt", Session Data Transport Multicast. E1.31 sACN shares this port because it sits on the same ACN root layer.

Multicast

SDT is a reliable multicast transport and ACN's EPI documents cover multicast address allocation. The specific group ranges are defined per EPI rather than by one fixed block, so confirm against the relevant EPI before configuring a switch.

What goes wrong

When someone on headset says "ACN" they almost always mean sACN (E1.31). They share a port and a root layer but not a purpose, and a device that speaks one does not necessarily speak the other at all.

ACN is a suite of documents plus EPIs that pin down discovery, addressing, port assignment and timeouts. Implementing SDT and DMP from the core documents alone will not give you anything interoperable.

DDL is the whole point and also the hard part. A device is only as self-describing as the DDL file the vendor shipped, and incomplete or stale descriptions are common.

SDT is session-based with membership and sequencing, so it carries state. Dropping and rejoining a session is not the free operation that restarting an sACN packet stream is.

Real-world deployment is narrow. ETC's Net3 and some Shure wireless gear use full ACN; most of the industry only ever met it through the sACN root layer, so third-party tooling is thin.

What speaks ACN (1)

Product	Direction	Notes
Wireshark Wireshark Foundation	in	Dissects the underlying ACN/E1.17 root layer (Root Layer, SDT, wrappers) that sACN rides on.

Typical use

ETC Net3 device configuration and control
The root layer that E1.31 sACN packets are built on
Self-describing device control where a DDL file replaces a hand-written driver
Shure wireless microphone system control

Sources

ANSI E1.17-2015 (R2025) — Architecture for Control Networks, free download — ESTA Technical Standards Program primary
ANSI E1.17-2010 — Architecture for Control Networks (title, scope, revision history) — ESTA / ANSI webstore primary
IANA Service Name and Transport Protocol Port Number Registry (5568, sdt — Session Data Transport Multicast) — IANA primary
Architecture for Control Networks (SDT, DMP, DDL, EPIs, relationship to E1.31, adoption) — Wikipedia

Understand the mechanism

Show networks How a one gets down a wire

Something wrong, or missing?

Known gaps on this entry: implementations. If you can source one of them, that is a ten minute pull request.

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