Spanning tree issue

acbenny · ‎09-16-2007

Hi all,

-Existing Switch C port 2 is blocked because of High MAC address compared with switch B

-All switch are connected via fast ethernet

-Switch A is root with priority 4096

Now

-Switch B port 2 set spanning tree cost to 500

why switch B port 2 still in forward state and why it will not change to block state ?

glen.grant · ‎09-16-2007

Not knowing the whole spanning tree structure and cost of your links , spanning tree thinks that where it is currently blocked is the highest cost back to the root so that is where it blocked the loop . It will only block one port in your whole setup and it has done that and eliminated the loop . I won't get into the whole spanning tree thing , best bet is just just go to the main cisco page and search on " configuring spanning tree " .

Francois Tallet · ‎09-16-2007

Try doing the same cost configuration on switch B port 1;-) The configured cost is only added on the root port.

Regards,

Francois