Dante, like many other network apps, uses multicast addressing. Multicast address (IP ver4 and 6) are reserved blocks that allow for one-to-many communications without broadcasting to all hosts.

There are several specific multicast addresses that need to be configured into the switch's configuration. See the setup instructions for details. These must be correct or systems will not be able to communicate with or discover one another.

"An IP multicast group address is used by sources and the receivers to send and receive multicast messages. Sources use the group address as the IP destination address in their data packets. Receivers use this group address to inform the network that they are interested in receiving packets sent to that group." https://en.wikipedia.org/wiki/IP_multicast

These are the ranges reserved for multicast (IGMP).

Local Network Control Block (224.0.0.0 - 224.0.0.255 (224.0.0/24))
Internetwork Control Block (224.0.1.0 - 224.0.1.255 (224.0.1/24))

Multicast specifics

"We use those switches for AV application (Audio, video, lighting). A lot of the traffic that travels on our networks is multicast traffic. To make sure that the switches don't get flooded with that multicast traffic, we enable IGMP snooping on all switches and we elect an IGMP querrier on one of the switches. We also enable "filter unregistered multicast" on all ports so the network don't get flooded by unregistered multicast (multicast traffic that does not have a listener)."

"The problem that we have when we activate "filter unregistered multicast", is that it also filters some of the 224.0.0.x and the 224.0.1.x traffic that is used for discovery, clocking and other protocoles that should be treated as broadcast due to purpose of that traffic. In my understanding, no device sends IGMP join or IGMP leave messages for those specific multicast groups."

"Also, I sometimes have to disable "filter unregistered multicast" on my ISL ports (uplinks) to make sure that the discovery/clocking/other traffic can get to other switches. By doing this, I generate more traffic on my ISL while reducing my bandwith overhead."

"The Filter Unregistered Multicast Tick boxes will - by design - block the discovery multicast packets that you are looking for. We saw this most commonly when staging (preparing) a number of boxes for a deployment using a bench CBS/SG switch that had AVoIP configuration - IGMP Snooping/querying/Bridge Multicast Filtering/Filter Unregistered Multicast/No flooding - enabled while simultaneously trying to stage (for example) a dante product that relies on discovery."

"There is a simple solution for this that involves statically adding the multicast addresses addresses that you require onto the switch so that they are not filtered entirely and discovery will function."

"Docs are your best friend - I have found Shure proves some great information for switch preparation for AVoIP w Dante deployments that will assist you going forward - see below. It will help with configuring the DSCP QoS values as well and not just in cisco land, other switch vendors as well. You could buy Netgear AV but...gross."

Reference: https://community.cisco.com/t5/switching/cbs350-igmp-and-filtering-unregistered-multicast/td-p/4531583

Referenced in this discussion: https://service.shure.com/Service/s/article/configuring-sg350-switch-for-shure-devices-and-dante?language=en_US

You will usually see this address simply appear in the list of unregistered addresses. Any client can initiate this, and you will see this in the unregistered list of multicast addresses. It is of no concern.

So, ipv6 ff02::1 is the ipv6 "ping" address.

"I am trying to cover the topic of IPv6 and was confused by SNMA and NDP. Does FF02::1 All-IPV6-Nodes Address mean that a multicast will be sent to all PCs, switches and servers on the same segment of the network?"

"ff02::1 produces a mac address which would be flooded by a switch (and very like not constrained by any multicast constraint feature) to even hosts that do not run IPv6. Of course, only IPv6 hosts would actually process the frame and send it higher up the protocol stack. To answer your question, ff02::1 is supposed to reach all IPv6 talkers on a local LAN segment. Enabling IPv6 on a node interface (router interface, switch SVI or routed port, or server/workstation/printer interface) will cause the node to listen on the destination mac address of 3333.0000.0001"

Reference: https://learningnetwork.cisco.com/s/question/0D53i00000WQRVBCA5/ff021-allipv6nodes-address-what-does-this-cover

This is another address you might see in the list.

"239.255.255.251 is a reserved IP address reserved by the IP address management agency and not assigned as a public or private IP. The reserved IP is generally used for special purposes, such as software, private networks, hosts, subnets, documents, conversions, multicast, broadcast, local communication, loopback, relay, link, mapping, testing and future usage. Non-professional users are rarely involved."

Below is a link to the list of uses and RFCs for reserved multicast group addresses.

Reference: https://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml