g/av • Posted by u/av_wizard • 1 days ago

Dante latency spikes with QSC Core 110f — DSCP not being honored?

QSC Core 110f as primary Dante clock, 4x Cisco SG350 switches, star topology, ~60 Dante endpoints (Shure, Biamp, Crown). Convention center install.

Set latency to 5ms in Dante Controller but seeing actual latency jump to 10-15ms during heavy traffic. Crown amps audibly glitching.

Network is a dedicated Dante VLAN, no other traffic. IGMP snooping enabled. I can't figure out what's queuing the packets.

💬 4 replies

4 replies

Best New Old Controversial

u/dante_dave • 1 days ago

Also check spanning tree topology. If you're running Rapid PVST+ and have any edge ports that aren't portfast-enabled, a device plug/unplug event can cause a brief topology change that stalls forwarding for ~1 second. Convention centers with rotating vendors are a classic place for this to bite you.

u/crestron_carl • 1 days ago

Check DSCP QoS on the SG350s. Dante marks audio packets DSCP EF (46). If the switches aren't mapping EF to the highest priority queue and scheduling it as strict priority, any burst of traffic (even control packets on the same VLAN) will cause queuing delay. On Cisco, verify QoS trust DSCP is enabled on the uplink ports, not just edge ports.

u/rack_randy • 1 days ago

Is the Core 110f running the latest firmware? QSC pushed a fix for a specific multicast handling bug that caused latency spikes in mixed-vendor environments. Worth checking before spending more time on switch config.

u/fiber_fred • 1 days ago

Crown DCi amps are known to have a tighter Dante latency tolerance than most endpoints. Some integrators just set them to 10ms and never look back. Try bumping your global latency to 7ms and see if the glitching stops — you won't hear the difference on music content.