The MSTP Configuration of stp root

Function Description

The multiple spanning tree protocol (MSTP) applies to the redundant network. MSTP is an improvement of STP and RSTP. MSTP prevents the proliferation and infinite cycling of the packets in the loop network. In addition, MSTP provides multiple redundant paths for VLAN data transmission to achieve the load-sharing purpose. The MA5680T/MA5683T/MA5608T supports MSTP, which is compatible with the STP and RSTP. It supports MSTP loop network that helps meet various networking requirements.

Function

The stp root command is used to set the current device as the root bridge of a specified spanning tree instance or to back up the root bridge. The tree network topology must have a root. When you need to specify the root of the spanning tree instance, run this command. After the current device is set as a root bridge, the current device is the root of the spanning tree and the device transmits Bridge Protocol Data Unit (BPDU) packets to the exterior at intervals.
The undo stp root command is used to cancel setting the current device as the root bridge of a specified spanning tree instance or to back up the root bridge. When you need to renew the root bridge after the network topology is changed, run this command. After the setting of the current device as the root bridge is canceled, the role of the current device in the current topology is changed.

NOTE:

After the current device is set as a root bridge or a root bridge is backed up, the system priority of the device will be automatically changed to the default setting, and users are not allowed to modify the system priority of the device.

Format

stp [ instance instance-id ] root { primary | secondary }
undo stp [ instance instance-id ] root

Parameters

Parameter	Description	Value
instance instance-id	Indicates the spanning tree instance ID. The value 0 indicates the Common And Internal Spanning Tree (CIST) instance and other value indicate the Multiple Spanning Tree Instance (MSTI).	Numeral type. Range: 0-16.
primary	Sets the device as the root bridge of the specified spanning tree instance. When you need to set the device as the root bridge, use this parameter.	-
secondary	Sets the device as the backup root bridge of the specified spanning tree instance. When you need to set the device as the backup root bridge, use this parameter.	-

Modes

Global config mode

Level

Operator level

Usage Guidelines

• By default, the device is neither a root bridge nor a backup root bridge.
• If you do not configure parameter instance instance-id, the configuration takes effect only on the CIST instance. If parameter instance-id is configured to 0, the current device is set as the root bridge or backup root bridge of CIST.
• One spanning tree instance can be configured with only one root bridge, but one or multiple backup root bridges.
  • When the root bridge fails or is powered off, the backup root bridge is used as the root bridge of the specified spanning tree instance.
  • Among multiple configured backup root bridges, the one with the smallest MAC address is used as the root bridge of the specified spanning tree instance.
• Root types the current device in different spanning tree instances are independent from each other. The current device can be the root bridge or backup root bridge in one or multiple spanning tree instances. In a spanning tree instance, a device cannot be root bridge and backup root bridge simultaneously.
  NOTE:

  • Do not configure one spanning tree instance with multiple root bridges. Otherwise, the calculation result will be unexpected.
  • You can set the current device as the root of multiple spanning tree instances. You can set multiple backup roots for a spanning tree.
  • Generally, it is recommended to specify a root and multiple backup roots for a spanning tree.

Example

To set the current device as the root bridge of spanning tree instance 1, do as follows:

huawei(config)#stp instance                                                     
{ INTEGER<0-16> }:1                                                          
{ priority<K>|root<K> }:root                                                    
{ primary<K>|secondary<K> }:primary                                             
                                                                                
  Command:                                                                      
          stp instance 1 root primary  

To set the current device as the backup root bridge of spanning tree instance 2, do as follows:

huawei(config)#stp instance                                                     
{ INTERGER<0-16> }:2                                                          
{ priority<K>|root<K> }:root                                                    
{ primary<K>|secondary<K> }:secondary                                           
                                                                                
  Command:                                                                      
          stp instance 2 root secondary  

To cancel setting the current device as the root bridge of spanning tree instance 1, do as follows:

huawei(config)#undo stp instance                                                
{ INTERGER<0-16> }:1                                                          
{ priority<K>|root<K> }:root                                                    
                                                                                
  Command:                                                                      
          undo stp instance 1 root  

System Response

• The system does not display any message after the command is executed successfully.