Configuring basic MSTP parameters

Follow these steps to configure basic MSTP parameters.

Enter global configuration mode.
```
device# configure terminal
```

Enable MSTP.

device(config)# protocol spanning-tree mstp

Specify the region name.
```
device(config-mstp)# region connemara
```
Specify the revision number.
```
device(config-mstp)# revision 1
```
Map MSTP instances to VLANs.
1. Map instance 1 to VLANs 2 and 3.
```
device(config-mstp)# instance 1 vlan 2,3
```
2. Map instance 2 to VLANs 4, 5, and 6.
```
device(config-mstp)# instance 2 vlan 4-6
```
Set a priority for an instance.
```
device(conf-Mstp)# instance 1 priority 28672
```
The priority ranges from 0 through 61440 and the value must be in multiples of 4096.
Specify the maximum hops for a BPDU.
```
device(conf-Mstp)# max-hops 25
```
This prevents the messages from looping indefinitely on an interface
Return to privileged EXEC mode.
```
device(conf-Mstp)# end
```

Verify the configuration.

device# show spanning-tree mst

 Spanning-tree Mode: Multiple Spanning Tree Protocol

 CIST Root Id: 8000.609c.9f5d.4800 (self)
 CIST Bridge Id: 8000.609c.9f5d.4800
 CIST Reg Root Id: 8000.609c.9f5d.4800 (self)

 CIST Root Forward Delay: 15; Hello Time: 2; Max Age: 20; Max-hops: 20
 Configured Forward Delay: 15; Hello Time: 2; Max Age: 20; Max-hops: 25;
 Tx-HoldCount: 6
 Number of topology change(s): 0

 Bpdu-guard errdisable timeout: disabled
 Bpdu-guard errdisable timeout interval: 300 sec
 Migrate Time: 3 sec

  Name           : connemara
  Revision Level : 1
  Digest         : 0xD5FF4C3F6C18E2F27AF3A8300297ABAA

  Instance        VLAN
  --------        ----
   0:             1,7,8,9
   1:             2,3
   2:             4-6

Note

Observe that the settings comply with the formula set out in the STP parameters section, as:

(2 × (forward delay - 1)) ≥ maximum age ≥ (2 × (hello time + 1))

or in this case: 28 ≥ 20 ≥ 6.

device# show running-config | begin spanning-tree
protocol spanning-tree mstp
 instance 1 vlan 2,3
 instance 1 priority 28672
 instance 2 vlan 4-6
 region connemars
 revision 1
 max-hops 25
 !
...

Save the configuration

device# copy running-config startup-config

Basic MSTP configuration example

device# configure terminal
device(config)# protocol spanning-tree mstp
device(config-mstp)# region connemara
device(config-mstp)# revision 1
device(config-mstp)# instance 1 vlan 2,3
device(config-mstp)# instance 2 vlan 4-6
device(conf-Mstp)# instance 1 priority 28582
device(conf-Mstp)# max-hops 25
device(conf-Mstp)# end
device# show spanning-tree mst
device# copy running-config startup-config