Spanning tree TCN

[carl_townshend]

Hi all, can anyone tell me what triggers the spanning tree change notifications, would enabling a port cause the switch to send one out? and what effect does it have on the network ?

[Kevin Dorrell]

TCNs are generated whenever there is a topology change, including enabling a port. This is one reason why it is advisable to put spanning-tree portfast on the access ports. That way, they do not generate TCNs every time a host comes on- or off- line.

Kevin Dorrell

Luxembourg

[carl_townshend]

can anyone tell me what these tcn's do to the network ?

[Francois Tallet]

STP topology change mechanism:

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

RSTP/MST topology change mechanism:

http://www.cisco.com/warp/public/473/146.html#newtop

Regards,

Francois