[c-nsp] mst & pvst

[Mateusz Błaszczyk]

On 25/03/2008, Adam Greene <maillist at webjogger.net> wrote:
> Hi,
>
>  I'm needing to set up a redundant trunk link between a 6509 and a 3750. The
>  6509 is running MST, the 3750 PVST. Am I going to have issues? I am assuming
>  so ...
>
>  Thanks,
>  Adam
>
>
>  ===
>  6509
>  ===
>
>  #MST (IEEE 802.1s)
>  set spantree fwddelay 15 mst
>  set spantree hello 2  mst
>  set spantree maxage 20 mst
>  set spantree mst maxhops 20
>  set spantree priority 0     mst 0-15
>  set spantree priority 32768 mst 16-4094
>
>  #MST Configuration
>  set spantree mst config rollback force
>  set spantree mst config name  revision 0
>  set spantree mst 0 vlan 1-4094
>  set spantree mst config commit
>
>  #vlan(defaults)
>  set spantree enable  1-16,30,40,99-100,123,128,192,840,888
>  set spantree fwddelay 15     1-16,30,40,99-100,123,128,192,840,888
>  set spantree hello    2      1-16,30,40,99-100,123,128,192,840,888
>  set spantree maxage   20     1-16,30,40,99-100,123,128,192,840,888
>  set spantree priority 32768  2-16,30,40,99-100,123,128,192,840,888
>
>  ====
>  3750
>  ====
>
>  spanning-tree mode rapid-pvst
>
>

read here

http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_example09186a00807b075f.shtml#mst1
http://www.cisco.com/warp/public/473/147.html#invalid_configuration

in a nutshell as long as mst priority for instance 0 (CST)  is better
then PVST, you are good to go, but also keep in mind not to disable
PVST on any VLANs on trunks between switches (no spt-disabled point to
point vlans). Also don't do asymetric vlan configurations on trunks -
remember that mst does not care about what vlans are actually
provisioned on links but how are the instances configured.

The links should give you a good starting point

Best Regards,

-mat