Cisco 2960 MSTP config

[Machi Ma]

Hello,

Currently I am working on MSTP config.  While check existing config it looks like my active VLAN is running under instance 1 (MST01). 

However, my peer switch is running instance 0. 

Q. First question is does it I should change back to instance 0?  and is it support for 2960?

Q. 2nd question is any risk during re-config?

Following please find output and config of MSTP port

----------------------------------------------------------------

asiaweb_sw3#show spanning-tree mst

###### MST00        vlans mapped:   2-9,11-19,22-149,151-299,301-349,351-399
                                     401-449,451-4094
Bridge      address 0017.0ea1.6400  priority  32768 (32768 sysid 0)
Root        address 0014.2287.351b  priority  32768 (32768 sysid 0)
            port    Fa0/12          path cost 200000
IST master  this switch
Operational hello time 2, forward delay 15, max age 20
Configured  hello time 2, forward delay 15, max age 20, max hops 20

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/2            Desg FWD 200000    128.4    P2p
Fa0/3            Desg FWD 200000    128.5    P2p
Fa0/4            Desg FWD 200000    128.6    P2p
Fa0/6            Desg FWD 200000    128.8    P2p
Fa0/7            Desg FWD 200000    128.9    P2p
Fa0/8            Desg FWD 200000    128.10   P2p
Fa0/9            Desg FWD 200000    128.11   P2p
Fa0/10           Desg FWD 200000    128.12   P2p
Fa0/11           Desg FWD 200000    128.13   P2p
Fa0/12           Root FWD 200000    128.14   P2p Bound(RSTP)
Fa0/13           Desg FWD 200000    128.15   P2p
Fa0/14           Desg FWD 200000    128.16   P2p
Fa0/15           Desg FWD 200000    128.17   P2p
Fa0/16           Desg FWD 200000    128.18   P2p
Fa0/17           Desg FWD 200000    128.19   P2p
Fa0/18           Desg FWD 200000    128.20   P2p
Fa0/20           Desg FWD 200000    128.22   P2p Bound(STP)
Fa0/21           Desg FWD 200000    128.23   P2p
Fa0/22           Desg FWD 200000    128.24   P2p
Fa0/23           Desg FWD 200000    128.25   P2p
Fa0/24           Desg FWD 200000    128.26   P2p

###### MST01        vlans mapped:   1,10,20-21,150,300,350,400,450
Bridge      address 0017.0ea1.6400  priority  32769 (32768 sysid 1)
Root        this switch for MST01

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/2            Desg FWD 200000    128.4    P2p
Fa0/3            Desg FWD 200000    128.5    P2p
Fa0/4            Desg FWD 200000    128.6    P2p
Fa0/6            Desg FWD 200000    128.8    P2p
Fa0/7            Desg FWD 200000    128.9    P2p
Fa0/8            Desg FWD 200000    128.10   P2p
Fa0/9            Desg FWD 200000    128.11   P2p
Fa0/10           Desg FWD 200000    128.12   P2p
Fa0/11           Desg FWD 200000    128.13   P2p
Fa0/12           Boun FWD 200000    128.14   P2p Bound(RSTP)
Fa0/13           Desg FWD 200000    128.15   P2p
Fa0/14           Desg FWD 200000    128.16   P2p
Fa0/15           Desg FWD 200000    128.17   P2p
Fa0/16           Desg FWD 200000    128.18   P2p
Fa0/17           Desg FWD 200000    128.19   P2p
Fa0/18           Desg FWD 200000    128.20   P2p
Fa0/20           Boun FWD 200000    128.22   P2p Bound(STP)
Fa0/21           Desg FWD 200000    128.23   P2p
Fa0/22           Desg FWD 200000    128.24   P2p
Fa0/23           Desg FWD 200000    128.25   P2p
Fa0/24           Desg FWD 200000    128.26   P2p

==================================================

spanning-tree mode mst
spanning-tree extend system-id
!
spanning-tree mst configuration
 name 1
 revision 1
 instance 1 vlan 1, 10, 20-21, 150, 300, 350, 400, 450

============================================

Thanks

[Julio E. Moisa]

Hi

The instance 0 represent the STP instance for the rest of the vlans that you are not specified under the instance 1. If your peer should be the backup root for these vlans 1, 10, 20-21, 150, 300, 350, 400, 450, so, yes, you should configure them under the instance 1. Talking about STP you always have keep an order to avoid any impact on your layer 2 network.

I always recommend make any change related to Spanning tree during a maintenance window in order to avoid any downtime. 

Hope it is useful

:-)