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Spanning tree pathcost configuration

Renata_Petras
Occasional Advisor

Spanning tree pathcost configuration

Hi,

we have 4 5400 switches, where SW1 is STP root and right now SW3 is blocking its Uplink to SW4, so it's root port is the Uplink to SW2.. I do understand this, because between SW1 and SW2 there is a 10GBit connection, so pathcost=2000, so the pathcost for SW3 in order to reach his root is 22000 (=20000 because of the 1GBit line between sw3 and sw2 and + 2000 for the 10Gbit line between sw2 and sw1) , but I need the uplink between SW3 and SW2 to be blocked and not the uplink between SW3 and SW4...
Could anyone please tell me where I have to use the spanning tree portnr pathcost xx command?

I tried to configure it on almost all possible uplinks and show spanning tree also shows that the pathcosts for the specific ports are changed, but not the IST Regional Root Path Cost.. I also know that every switch adds pathcosts in the BPDU packet, which it sends to the next switch, but it looks like I forgot a command... =(

stp.jpg

 

This is how it should look like: (port between SW3 and SW2 should be blocked)

 

stp2.JPG

 

Thanks very much in advance!!!