Q:

STP in a mixed environment

Good day all,
We have some a mixed environment of Dell Powerconnect and Cisco switches. On both brands of switches, I am seeing numerous STP topology changes. I've decided to try on work on the Dell switches first. The root switch is a Cisco 6500.
Though the logs on the Dell switches show numerous topology changes within seconds, the root bridge remains the same. It is my understandings that topology changes should only really occur when switches are added or removed or root ports go down. Should I be concerned about these topology changes? Any help will be greatly appreciated. Thank you.

A:

Are you actually seeing Toplogoy changes or are you seeing only Topology Change Notifications? If the latter than that's fairly normal but TCN's can cause a degree of network flooding if there are too many of them. One source of TCN's that can cause TCN flooding are host ports that aren't configured with the Cisco equivalent of portfast. If your host connected ports aren't configure for portfast they should be.

