MST configuration on Cisco Nexus 7k switches

Step 1. Check the current STP mode.

N7k (config-if-range)# show spanning-tree vlan 30

VLAN0030

Spanning tree enabled
protocol rstp
———<<<<<<<<<<<<<

Root ID Priority 32798

Address 0005.73bc.067c

This bridge is the
root

Hello Time 2
sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority
32798 (priority 32768
sys-id-ext 30)

Address 0005.73bc.067c

Hello Time 2
sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts
Cost Prio.Nbr Type

—————- —- — ——— ——–
——————————-

–

Eth1/1 Desg FWD
2 128.129
P2p

Eth1/2 Desg FWD
2 128.130 P2p

Step 2 . Enable MST
mode. By default RSTP-PVST+ is enabled.

N7k (config)#
spanning-tree mode mst

Step 3. Enter in MST
configuration mode

N7k (config)# spanning-tree mst configuration

Step 4. Give the name
to MST process. It should be same on all the switches otherwise switch will not
recognize each other.

N7k(config-mst)# name MST1

Step 4. Give the revision number. Similar to the name, it
must be same on all switches in L2 domain.

N7k (config-mst)# revision 1

Step 5. Create instance as per your requirement and map the
vlan to it. Make sure you don’t create unnecessary large number of instance.

N7k (config-mst)# instance 1 vlan 30,40

Step 6. This is an optional step to configure the MST root.
We can elect different switch as root for different MST instance.

N7k (config)# spanning-tree mst 1 root primary

N7k # show spanning-tree mst 1

##### MST2 vlans
mapped: 50,60

Bridge address
001b.54c2.67c2 priority 24578 (24576 sysid 2)

Root this switch for MST1
—————-<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

Interface Role Sts
Cost Prio.Nbr Type

—————- —- — ——— ——–
——————————–

Eth1/1 Desg FWD
2000 128.129 P2p

Eth1/2 Desg FWD
2000 128.130 P2p