QOS expedite causing access issue with STP

[zackburf]

I have Adtran switches across my network. What we have found an issue with access when STP blocks a port in a specific instance.  The instance we found is when there is a loop in an unmanaged switch that is connected to the Adtran.(I know unmanaged switches are the devil and budget wise we are working to get rid of them.)  What happens is a user creates a loop in their office with the unmanaged switch and then the Adtran kills that link to the unmanaged switch. This is great because it stops the loop from hurting the network.  All the computers on the Adtran retain internet access and voip phones work fine.

Here is the weird part, when it blocks that port we lose all remote access to the switch. I have confirmed STP is blocking that port by consoling into the switch.  This only happens we are using QOS to expedite voip traffic. When we turn qos off the STP still blocks the port and we keep remote access.

I have tested this in a lab enviroment with not other traffic besides my computer and the loop in an unmanaged switch and the same thing happens. I have found when I weight the qos VOIP queue to 255 instead of expedited I keep access as well.

My question is this.  With VOIP do I need to keep the voip queue at expedited traffic or can I just leave at 255.(The other three queues are set to 25)

Second question is does anyone know why expediting COS vlaue 5 traffic in queue 4 is stopping remote access and pings during the loop.

[Dieselboy]

In Adtran-speak, what do they mean when expediting COS 5? In Cisco-speak, they talk about voice traffic being DSCP 'EF' which is Expedited Forwarding', not sure if it's related.

Which STP type are you using?

There's a few things going on here and I think more info is needed to be able to make some proper suggestions to you