The issues may not be limited to the BRK 254 switch.
We have discovered multicast flooding on the BRK 254 (VLAN 70) switch, due we believe, to faulty NIC drivers on specific models of Dell PCs. The issue occurs when the computers go into sleep mode, when they are up and working they are not flooding.
Bill and his team are planning to upgrade the drives this morning.
We will keep you posted.