"Rampley, Jim" wrote:
I'm reading the Cisco LAN switching book (great book)! I've got a question about topology change notification BPDU's. If you have a port on a switch that is NOT using portfast with say a workstation or server connected. When that port comes up spanning tree will run. My question is once it goes into the forwarding state will a TCN BPDU be sent? There are three rules that say when a TCN BPDU will be sent. The rule that I think applies is "When a port is put in the forwarding state and the bridge has at least one designated port."
I realize most of the time you would want to use portfast in this situation since you don't want to be running spanning tree while the machine is trying to booting up. I just didn't realize you would actually be saving traffic on your network and also the effects of having to flush the CAM quicker. Someone could actually tweak the STP timers down so they wouldn't have to use portfast, but you could have a flood of TCN BPDU's every morning.
Jim
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