AV Network Issues: Flickering TVs and High Dante Audio Latency | Fabric engine & Voss | New Building

[Glenn_VUB]

Hey everyone,

We’re working on the network for a new building that has two routers on the ground floor (floor 0) and a bunch of switches spread across floors 0 to 5, all linked back to those two routers. Each floor has several switches—some general ones and some dedicated to AV (audio/video). If you check out the the topology, you’ll see what I mean. We have 4 normal switches & 4 AV switches that are setup the same way for each floor as this topology. On the right we have our 2Routers on floor 0.

We’ve been configuring a ton of devices on the AV switches, but we’ve run into a couple of problems:

First issue
On floor 1, there’s a room with multiple cameras and multiple TVs. The floor has four AV switches. If we connect the cameras to Switch 1 and the TVs to Switch 2, 3, or 4, the TVs flicker. We’re only seeing a few dropped packets, so it’s not obvious what’s causing it. Strangely, if we put everything on the same switch, the flickering stops.

Has anyone run into something like this before?

Second issue
We’re setting up some Dante-enabled devices for audio. Normally, if you speak into the mic, the audio should come out through the speakers, but we’re seeing high latency (50–70ms) on these devices, even though they’re all on the same local network. This might be why our speakers aren’t working correctly.

We suspect these two issues could be related, so we’d love any ideas on how to troubleshoot or fix them. We don’t have these problems in our older buildings, where we use 4950s in a stack with 7200VSPs. Our current firmware is 8.10.1+. Everything’s running Fabric Engine and VOSS on the routers.

For anyone not familiar with Dante, I’ve attached a PDF with more info.

 

Thanks in advance for any help!

– Glenn

[Yoann_Jonard]

Hello Glen,

I would look into :

1. Are the ports QoS trusted ? By default I can see a port is L2 trusted (802.1p) and L3 trusted (DSCP), but if you are using auto-sense it's remapped.
2. Are you hitting a resources limit for multicast ? Check "show qos cosq-stats cpu-port" and "show qos cosq-stats int #INT-NAME" for any dropped packets.
   
   1. You can also take a look at the scaling for multicast for your switch model in the release notes here.
3. Are you using L2 multicast or L3 ?
4. Do you have rate limiting in place ? (show int gi rate-limit)
5. Do you have shaping in place ? (show int gi shape)

Best regards,