Pathcost Method Long or Pathcost Method Short in Nexus Switches ?

[Chaker BCHIR]

Hi All,

What's the default method of Spanning-tree Calculation of Cost (Pathcost Method Long 32 bits or Pathcost Method Short 16 bits) in Cisco Nexus Switches ?

As I understand, if we have > 1 G links in our Architectures (LANs, DCs, ...) and nowadays it's the case, we should change
this methode on all switches (to Long). So, did you do this manually, or is it the default behaviour of recant OSs, or  you did not care about this anymore ?

[balaji.bandi]

spanning-tree pathcost method long enabled, spanning tree calculates the best forwarding path according to the link bandwidth to the root and not based on hop count.

[Chaker BCHIR]

Thnks for reply !

I think that Spanning-tree always calculates the best path to a destination based on Cost (not in hop counts). And the issue here is in relation with Cost : with the method Short it uses 16 bits in the field of this cost and here it does not differ between 1G, 10G, 40G, 100 G ... that's whay in DCs I think we should use the Long method (32 bits).

And I want to know if in Nexus this method (long) is the default behaviour and if not should we change it manually in all switches ?