An issue has been identified where AoIP Endpoints , Dante audio devices, within a shared multicast domain (VLAN) experience intermittent clock leader instability.
Instead of maintaining a single, designated Dante clock leader per room, multiple devices simultaneously elect themselves as the clock leader, leading to a "split-brain" scenario.
This issue was reported after upgrading Juniper switches to Junos OS version 23.4R2-S7.
Audio Degradation: Audio drops in and out intermittently, or goes completely mute for several minutes at a time.
Clock Instability: Dante Controller displays multiple devices electing themselves as the clock leader simultaneously within the same VLAN.
Multiple End-Point locations or rooms share the same broadcast/multicast domain (VLAN) , IGMP and IGMP Snooping are enabled on the (VLAN)
Each end-point room switch has an Integrated Routing and Bridging (IRB) interface acting as the designated IGMP querier.
The underlying failure is related to PR1873129.
Under specific circumstances on this firmware version, the switch improperly handles or drops critical multicast traffic—specifically IGMP queries or PTP (Precision Time Protocol / IEEE 1588) clock sync packets used by Dante.
When Dante devices lose tracking of the primary clock leader due to IGMP snooping table corruption or packet loss caused by the bug, other devices assume the leader is offline and promote themselves, resulting in split-brain "multiple clock leader" scenarios.
Testing isolated individual test VLANs and disabling features like immediate-leave did not alleviate the symptoms, confirming a platform/firmware-level issue rather than a standard multicast misconfiguration.
Workaround:
1-To resolve the issue with a workaround "add a master clock",
Designate a Preferred Leader (Master Clock) within Dante Controller to stabilize the clock hierarchy."
or
2-To mitigate the issue, apply the official Juniper workaround for PR1873129 and harden the Dante clock hierarchy.
KB workaround: Use following CLI command to flood specific multicast packets in a specific vlan. "set vlans vlan100 multicast-snooping-options flood-groups 224.0.1.129"https://prsearch.juniper.net/problemreport/PR1873129