g/av • Posted by u/dante_dave • 1 months ago

Dante audio dropping packets on a gigabit switch — multicast storm?

Running a Dante network on a Cisco SG350 managed gigabit switch. 14 Dante devices (mix of Yamaha QL5, Shure MXA, BSS BLU-100, Crown amp rack units).

Started getting intermittent audio dropout across all devices simultaneously. Duration: 50-400ms. No pattern to timing.

Dante Controller shows packet loss events on every device at the same moment — classic multicast issue.

Switch is configured: IGMP snooping enabled, QoS configured (priority queue for audio traffic), Dante on VLAN 200 separate from guest and production traffic.

Pulled the switch logs: at every dropout, there's a Spanning Tree topology change event. My STP configuration is wrong somewhere.

Has anyone dealt with STP topology changes causing Dante dropouts?

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u/av_wizard • 1 months ago

STP topology changes killing Dante is a known issue and you've diagnosed it correctly. The fix: enable PortFast (or Rapid PVST+ edge ports) on every port that connects to an end device (not switch-to-switch uplinks). PortFast makes those ports skip the listening/learning STP states and go directly to forwarding, which prevents the topology change events that flood the multicast table and kill Dante streams.

u/crestron_carl • 1 months ago

We had this exact issue on a university performing arts center — 40 Dante devices, unmanaged switches mixed in with managed, STP going crazy. Replaced the unmanaged switches, enabled PortFast everywhere. Zero dropouts in 18 months since.

u/cat6_carlos • 1 months ago

Also: enable BPDU Guard on the same PortFast ports. This prevents a rogue device from sending BPDU frames (which trigger STP recalculation) if someone plugs something unexpected into your Dante VLAN. On a locked-down AV network, BPDU Guard is good hygiene.