Introduction to Dante Clocking
Clocking is a critical part of all digital audio systems. Every digital audio device contains a clock, which is used to accurately time out the capture and playback of digital audio samples, much like a metronome helps a musician keep time. When multiple digital audio devices are connected together, they all need to share a common reference to make sure that audio is captured and played back in sync. Dante achieves this using the Precision Time Protocol, which is also known as PTPv1 or IEEE1588-2002.
In a Dante network, one device is assigned the role of Primary Leader Clock, and the rest of the devices will synchronize their internal clock to the Primary Leader Clock. This device can either be elected automatically by way of the PTP protocol, or it can be manually selected by a user in Dante Controller.
Unless a network has hundreds of devices, any Dante device can serve as the Primary Leader Clock without any performance penalty. It's best to select a stable device which is unlikely to be rebooted or turned off as the Primary Leader Clock to avoid audio glitches on the network if the Primary Leader Clock role is transferred to a new device.
The Primary Leader Clock does not need to be synchronized to any particular real-world time source, such as GPS. All that matters is that the device can maintain precise time over long periods, like a good wristwatch does. This ensures that audio is always captured and played back accurately. All Dante devices have dedicated chips on board to handle this task.
How do I set up Dante clocking?
As previously mentioned, in a normal Dante network one device will automatically be selected as the Primary Leader Clock. If you have a preference for which device or devices should be the preferred clock, then select those in Dante Controller on the Clock tab. Ensure that one and only one device is listed as the Primary Leader Clock, at the top of the Dante Controller screen.
Troubleshooting Clock Issues
The PTP clock protocol relies on Multicast IP traffic to communicate among devices on a Dante network. It also assumes that Ethernet switches will consistently pass the clock packets to their destination immediately upon receiving one. While most unmanaged Ethernet switches handle this task well, some do not. The two most common causes are Energy Efficient Ethernet (IEEE 802.3az, or Green Ethernet), and incorrectly configured Multicast settings.
Be sure that the network switch you purchase for Dante networks is not on our Disqualified List. In addition, check the product documentation to ensure that the switch does not have Energy Efficient Ethernet, Green Ethernet, or 802.3az--or that it can be disabled if it does.
If the switch supports configuration, you may need to disable all Multicast Filtering for smaller networks of Dante-only devices. For larger networks or networks with AES67, see Dante Networks and IGMP Snooping, and our Enterprise Network Troubleshooting Checklist.
In some cases, it may be necessary to isolate Dante Clock traffic to a small network.
For the curious, we have a more detailed FAQ on clocking: Dante and AES Clocking In Depth.
