Does portfast affect spannign tree topology changes

[d-fillmore]

When looking at spanning tree stats on a LAN consisting of Catalyst switches, I see a lot of spanning tree changes when I am positive that the actual tree hasn't changed. Do Catalyst switches see a port going up and down as a spanning tree topology change? can this be remedied by configuring portfast on all user ports as currently the spanning tree stats don't give me much useful info.

Thanks

[Prashanth Krishnappa]

Yes. Catalyst switches do see a port going up and down as a spanning tree topology change. If the ports connect to a end device, you'll need to enable portfast not only to avoid TCN generation but also to reduce startup connectivity time

http://www.cisco.com/warp/public/473/17.html