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Originally posted by ahjeff

With STP, the switch transmits packets. These will interfere with the audio.

Hope this helps

Thanks, that does help my understanding greatly! I wanted a little review on how STP works (I am CCNA), so I opened up the gigantic Cisco book and re-read the chapter on STP.

If I am correct in my understanding, the packets the switch transmits interfere with the audio because they cause a delay in forwarding. That is, when the switch is first powered on, it goes through and decides if there are any redundant links and disables them. Until that is finished (~50s), all frames are blocked. Then, if there is any change in the network, it will have to re-converge by repeating the procedure and taking another ~50s.

To prevent this, I can disable STP on that VLAN only and leave STP running on my data VLAN (for internet access, not control data)? Of course this relies on the assumption that I can use VLAN trunking between switches (my switches have 1G uplinks with QoS so bandwith should not be a problem).

I am glad to know about the latency – somebody told me that switches would add too much to be useful.