manipulate spanning tree

[as00001111]

Hi all,

I got a network with a mix of cat9500 and Nexus switches. All links are 10Gig Layer2 trunk links.

SW1 is the root. All other switches got default priority.

I would like that link between SW4 and SW5 is blocked.

in other words, I would like that SW4 takes the path to the root through SW3.

Can you tell me how to achieve that?

Thank you.

 

[Spooster IT Services]

Hi @as00001111,

Check the path cost using the command "show spanning-tree vlan 1" and Increase the path cost on SW4 at a port connected to SW5.

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[Seb Rupik]

Hi there,

The STP path cost to the root bridge via SW5 will be 4 while via SW3 will be 6. Increasing the link cost as @Spooster IT Services  suggests, on the SW4 interface connecting SW5 to a value >=5 will cause STP to reconverge to your preferred topology.

! SW4
!
int te1/x/x
  spanning-tree cost 5
!

cheers,

Seb.