We recently setup CiscoWorks and we are constantly (about every 10 minutes, sometimes more frequently) getting notifications of "STP Topology Change". I checked the logs on the switches as well as HSRP and CPU utilization and port utilization. I don't see any evidence or possible causes of Topology changes. We do use VOIP phones. I'm wondering if the fact that all the access ports are actually trunk ports (VOIP and client PC) could be causing these alerts when machines are unplugged or turned off. Has anyone experienced this?
This is coming from DFM based on the reception of the topologyChange trap from the switch.
Typically, voice ports are not trunks, but rather one access port which can support two vlans (a primary and a voice). In this case, portfast should be enabled, and topology changes will not occur. For example:
switchport access vlan 30
switchport mode access
switchport voice vlan 20
spanning-tree bpduguard enable