Dante Multicast Communications Revisited

What is Dante?

Dante is the product name for a combination of software, hardware, and network protocols that delivers uncompressed, multi-channel, low-latency digital audio over a standard Ethernet network using Layer 3 IP packets. Developed in 2006 by the Sydney-based Audinate, Dante builds on previous audio over Ethernet and audio over IP technologies.

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Dante audio networking is widely used across industries — live event venues, schools, corporate conference rooms, houses of worship — anywhere that needs dependable, crystal-clear audio distributed across multiple endpoints. It has become the gold standard for digital audio transport.

Dante is a proprietary Network Layer audio transportation protocol, detailed information is not directly available from Audinate (there are some 3rd party resources, but they mostly lack the necessary precision as one may require for the desired network configuration).

LAN Separation

The following setup separates the LAN into two areas, one containing all Dante audio devices and the other containing the remaining parts, the wireless access points and the outbound router. The separation is done using ixdp acting as a (mostly) transparant bridge. This has the following advantages:

• Dante devices obtain their IPv4 address via DHCP as all other devices.
• Dante devices can be updated with Dante update manager or vendor specific programs (like RedNet Control).
• PTPv1 is kept in the Dante LAN part only, this avoids propagating high priority PTP packets towards WLAN devices.
• mDNS multicast is forwarded originating from the Dante LAN, but not in the reverse direction.

This separated LAN looks then basically like this:

Separated LAN

Example Ethernet Statistics

Here’s an example output of if.uestat which shows the Layer2 packets sent by the following two devices:

• 00:1d:c1:07:ac:30 Focusrite RedNet AM2 (Stereo headphone and line output device)
• 00:1d:c1:10:e9:50 FERROFISH Verto65 (64x64 Kanal ADATDante Converter)

Example Ethernet Statistics of 2 Dante Devices

Multicast Ethernet DST Addresses used by Dante

Here’s a summary which MAC destination Multicast addresses are used by Dante:

• The mDNS Multicast address 01:00:5e:00:00:fb allows Dante controller to find all active Dante devices in the LAN.
• PTPv1 packets are forwarded with DSCP value CS7.
• There are two types of control and monitoring multicast in use.

ixdp

ixdp acts as a separating bridge and allows to block Dante multicast and mDNS multicast separately.

Starting ixdp

$ sudo ixdp enp1s0f0 enp1s0f1 --daemon
ixdp going to background ...
$ _

ixdp.rpcl

"ixdp@u32 >>" "rpcl.prompt" !
"green" "rpcl.prompt.color" !

0 tap.rx.enable
1 tap.rx.enable

0 dante.mcast.drop.enable
1 dante.mcast.drop.enable

0 mdns.mcast.drop.enable

Resources

• Dante/Audinate
• Dante Virtual Soundcard
• How does Dante use DSCP / Diffserv priority values when configuring QoS?
• Presision Time Protocol
• Multicast
• IXDP

This post first appeared on blog.inlab.net .