Dante PTP Clocking and External Clock Sources

Every Dante network needs a single timing reference. Dante achieves this using IEEE 1588-2002 Precision Time Protocol version 1 (PTP v1). Understanding how PTP leader election works — and how to introduce an external clock when needed — prevents the most common class of Dante synchronisation issues.

How PTP Leader Election Works

When Dante devices power up on the same network, they run the Best Master Clock Algorithm (BMCA). Each device broadcasts PTP announce messages. BMCA compares clock quality, priority settings, and MAC address to elect a single Primary Leader Clock. All other devices become followers and lock their internal sample clocks to the leader's timing.

The result is sample-accurate synchronisation across every device on the network — the defining property that makes Dante suitable for multi-room, multi-zone, and broadcast installs.

In Dante Controller, the Clock Status tab shows which device has been elected Primary Leader and the lock status of all followers. If this tab shows missing data or the lock state is not stable, that is usually a network issue (see the Multiple Leader Clocks article) rather than a device fault.

Dante Clocking Domains

Ad-hoc (unmanaged) networks — Dante devices without DDM or Dante Director use PTP subdomain _DFLT. This is also the default subdomain used by most third-party PTP v1 clock devices.

DDM or Dante Director managed networks — each domain uses a custom subdomain value assigned by DDM/Director. The specific subdomain is not displayed in the DDM/Director interface. This matters if you want to introduce an external clock into a managed network (see below).

Using an External PTP v1 Clock as Leader

Some installs have an existing house clock distribution system — a grandmaster clock feeding other AV or broadcast equipment. Dante can be made to follow a non-Dante PTP v1 clock source as its Primary Leader.

To configure an external PTP v1 clock as Dante leader:

1. On the external clock device, set PTP version to v1 and subdomain to _DFLT (the Dante default for unmanaged networks)
2. Assign the external clock a lower stratum (priority) value than the Dante devices — lower stratum = higher priority in BMCA
3. Set the external clock as "preferred leader"
4. In Dante Controller Clock Status tab, disable Preferred Leader and disable Enable Sync to External on all Dante devices — this lowers their BMCA priority and allows the external clock to win the election

Once the external clock is elected, Dante Controller will display "Unknown Device" as the Primary Leader Clock. Hovering over it shows the MAC address of the external clock, confirming which device has been elected.

External Clocks on DDM/Dante Director Managed Networks

On managed networks, DDM assigns custom PTP subdomains. Because most third-party PTP v1 clocks cannot edit their subdomain value, there is a workaround:

In the DDM or Dante Director interface, switch the domain's clocking mode to AES67. This applies PTP v2 domain 0 to the domain and forces the PTP v1 subdomain back to _DFLT. Your external PTP v1 clock can then participate in leader election using the standard subdomain.

Contact Audinate support if you need the custom subdomain value for a specific DDM domain — it is not exposed in the UI.

AES67 and PTP v2

AES67 mode uses IEEE 1588-2008 PTP version 2 on domain 0. If your external clock runs PTP v2 rather than v1, you need to enable AES67 mode on the Dante devices and ensure the external clock uses PTP v2 domain 0.

AES67 interoperability also enables routing between Dante and non-Dante AES67 devices. This is covered in DDM and Dante Director documentation.

Common Clocking Faults

"System clock has gone backwards" error (262): Indicates a large clock jump — typically caused by two BMCA elections converging differently, or a device reconnecting after a network outage and being elected leader before it has locked to the network. Usually self-correcting within seconds. If persistent, check for multiple leaders (IGMP issue) or a device with Preferred Leader enabled that has been offline.

Devices showing as Listening in Dante Virtual Soundcard: DVS locks to PTP via the network interface. If DVS shows Listening rather than a clock status, it cannot see PTP traffic — check firewall, NIC selection, and that the Windows ConMon service is running.

High measured latency in Dante Controller: If the latency graph shows values far above the configured setting, clock synchronisation may be broken. Latency is calculated relative to each device's clock — if clocks are not synchronised, the calculation is on a mismatched baseline and values are meaningless. Fix the clock issue first.

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This article was adapted from Audinate's original guidance: "Can I utilize a non-Dante PTPv1 clock leader device to provide clocking for a Dante network?" — https://support.getdante.com/hc/en-gb/articles/5772739675935-Can-I-utilize-a-non-Dante-PTPv1-clock-leader-device-to-provide-clocking-for-a-Dante-network Habitech-edited for UK trade installer context. Original © Audinate Pty Ltd.