We have had problems with the Dante master clock being "odd". So I did some research and found this information to be very informative.
Question Sometimes, I see multiple devices listed as Primary Leader Clock or my devices appear and disappear in Dante Controller. Could IGMP Snooping or my network configuration be the cause of these issues?
Shure Dante-enabled devices can exhibit communications issues when connected to managed switches where IGMP (Internet Group Protocol Management) Snooping is not configured correctly. These issues may manifest themselves as:
Multiple devices appear as the Primary Leader Clock in Dante Controller. Devices do not appear or information is missing in Dante Controller, Shure Update Utility, Shure Designer, or Shure Microflex Wireless Software. High levels of network traffic or bandwidth utilization on all devices.
Multiple devices appear as the Primary Leader Clock in Dante Controller.
Devices do not appear or information is missing in Dante Controller, Shure Update Utility, Shure Designer, or Shure Microflex Wireless Software.
High levels of network traffic or bandwidth utilization on all devices.
If you are not experiencing any of these issues, you likely do not need to worry about IGMP snooping. If you are experiencing one or more of these issues, then there are two possible solutions: disable IGMP Snooping and Multicast filtering, or configure IGMP Snooping on the switch correctly.
When to Disable IGMP Snooping Small, isolated networks with a single switch that have only Shure or other Dante-enabled devices generally do not require IGMP snooping, as the amount of Multicast generated will be very low (Multicast traffic is used only for clocking, discovery, and control in these cases—not audio). In these cases, disable all Multicast filtering or use an unmanaged, gigabit switch that does not support EEE (ensure it is not listed under Disqualified Network Switches for Shure Dante Devices).
When to Configure IGMP Snooping - IGMP Snooping is required when:
IGMP Snooping helps prevent transmission of Multicast traffic to ports that don't need them. On larger, shared networks with Dante or AES67 multicast flows, IGMP Snooping greatly reduces the amount of Multicast traffic on the network by only forwarding Multicast data to the devices that request it. For more details on how IGMP works, please see Multicast and IGMP In Depth.
How to Configure IGMP Snooping You should only attempt to configure IGMP Snooping on isolated AV networks. Do not make changes to an Enterprise network without proper authorization. Please refer to Configuring a Network Switch for Shure Devices and Dante/AES67 for detailed instructions on how to properly configure your network switch to support Shure Dante-enabled devices.
In some rare cases, you may need to add IGMP static filters to each Dante-enabled device port on the VLAN. Only add these if your switch does not work after configuring it according to our switch configuration guide, or when using high-bandwidth Multicast devices such as IP Video senders/receivers (such as Crestron NVX). Static filters ensure that the PTP, mDNS, Discovery, and audio traffic is always available throughout the VLAN. IGMP static filters may be required for:
Additional Tips
Ensure that Filter Unregistered Multicast is not enabled. Some switches ship with this feature enabled. This blocks traffic that should be allowed (mDNS, PTP, Dante Discovery) and usually results in devices failing to appear in Dante Controller, Shure Update Utility, and Shure Designer.
If you experience intermittent audio, then run a Wireshark trace on a PC connected to the Dante network. It may show IGMP Query messages from multiple sources. Contact Shure Applications Engineering for help interpreting Wireshark traces.
Fast Leave will not harm a Dante network and is generally required for Multicast video traffic. Avoid IGMP proxies, unless you are CERTAIN you know how it behaves.
If you intend to multicast over multiple switches, you will need to configure multicast router ports. Multicasts and IGMP messages will be sent through these ports. When multicast router ports are not configured, unnecessary multicast packets may be sent between switches, and some necessary multicast packets may fail to be delivered. For example, the preset recall of different MTX/MRX systems will not be linked. With the above settings, auto learning has been enabled, so no special multicast router port settings are required. If you are using another switch, you will need to identify the port that connects the switches as a multicast router port.
Select the “Enable” check boxes next to IGMP Snooping Status, MRouter Ports Auto Learn, and IGMP Querier Status. Also, we recommend that you set Query Interval to “30” (seconds) and set IGMP Querier Version to “IGMP V3”. When the query interval is large, the time required before multicast starts working properly becomes longer. Dante supports both IGMP V2 and V3, but all switches in the network should be running the same version. So if the network includes switches which support only IGMP V2, be sure to select "IGMP V2" as the IGMP querier version.
There should only be one IGMP querier in the network.
There should only be one IGMP querier in the network. Multicast will work even if there are multiple queriers, but multiple IGMP messages will end up being sent. In the above settings, the querier is determined automatically, so no special querier settings are required (one of the switches in the network will automatically become the querier). If there are switches with different settings in the network, make sure to configure the switches so that there is only one querier.
Dante Multiple Clock Leaders - IGMP Notes