Example for Configuring Basic RSTP Functions

This example shows how to configure basic Rapid Spanning Tree Protocol (RSTP) functions.

Networking Requirements

On a complex network, loops are inevitable. With the requirement for network redundancy backup, network designers tend to deploy multiple physical links between two devices, one of which is the master and the others are the backup. Loops are likely or bound to occur in such a situation. Loops will cause broadcast storms, thereby exhausting network resources and paralyzing the network. Loops also cause flapping of MAC address tables and thus damages MAC address entries.

RSTP can be deployed on a network to eliminate loops by blocking some ports, and it is developed to implement the rapid convergence based on STP but outperforms STP. On the network shown in Figure 1, after DeviceA, DeviceB, DeviceC, and DeviceD running RSTP discover loops on the network by exchanging information with each other, they trim the ring topology into a loop-free tree topology by blocking a certain port. In this manner, replication and circular propagation of packets are prevented on the network and the devices are released from processing duplicated packets, thereby improving their processing performance.

Figure 1 Networking diagram of configuring basic RSTP functions

Interfaces 1 through 3 in this example represent GE 0/1/1, GE 0/1/2, and GE 0/1/3, respectively.

Configuration Roadmap

The configuration roadmap is as follows:

Configure basic RSTP functions, including:
1. Configure the RSTP mode for the ring network.
2. Configure primary and secondary root bridges.
3. Set path costs for ports in each MSTI to block certain ports.
4. Enable RSTP to eliminate loops, including:
  - Enable RSTP globally.
  - Enable RSTP on all the interfaces except the interfaces connected to terminals.
  RSTP is not required on the interfaces connected to terminals because these interfaces do not need to participate in RSTP calculation.
  
  By default, RSTP is enabled on a Layer 2 interface.
Configure RSTP protection functions, for example, root protection on a designated port of a root bridge in each MSTI.

Data Preparation

To complete the configuration, you need the following data.

GE interface numbers, as shown in Figure 1
Primary root bridge DeviceA and secondary root bridge DeviceD
Path cost of a port to be blocked (20000 is used in this example)

Procedure

Configure basic RSTP functions.

Configure the RSTP mode for the devices on the ring network.

# Configure the RSTP mode on DeviceA.

<HUAWEI> system-view
[~HUAWEI] sysname DeviceA
[*HUAWEI] stp mode rstp
[*HUAWEI] commit

# Configure the RSTP mode on DeviceB.

<HUAWEI> system-view
[~HUAWEI] sysname DeviceB
[*HUAWEI] stp mode rstp
[*HUAWEI] commit

# Configure the RSTP mode on DeviceC.

<HUAWEI> system-view
[~HUAWEI] sysname DeviceC
[*HUAWEI] stp mode rstp
[*HUAWEI] commit

# Configure the RSTP mode on DeviceD.

<HUAWEI> system-view
[~HUAWEI] sysname DeviceD
[*HUAWEI] stp mode rstp
[*HUAWEI] commit

Configure primary and secondary root bridges.

# Configure DeviceA as a primary root bridge.
```
[~DeviceA] stp root primary
[*DeviceA] commit
```
# Configure DeviceD as a secondary root bridge.
```
[~DeviceD] stp root secondary
[*DeviceD] commit
```
Set path costs for ports in each spanning tree to block certain ports.
- The values of path costs depend on path cost calculation methods. Use the Huawei proprietary calculation method as an example to set the path costs of the ports to be blocked to 20000.
- All devices on a network must use the same path cost calculation method.
# On DeviceA, configure the path cost calculation method as the Huawei proprietary method.
```
[~DeviceA] stp pathcost-standard legacy
[*DeviceA] commit
```
# On DeviceB, configure the path cost calculation method as the Huawei proprietary method.
```
[~DeviceB] stp pathcost-standard legacy
[*DeviceB] commit
```
# On DeviceC, configure the path cost calculation method as the Huawei proprietary method and set the path cost of GE 0/1/1 to 20000.
```
[~DeviceC] stp pathcost-standard legacy
[*DeviceC] interface gigabitethernet 0/1/1
[*DeviceC-GigabitEthernet0/1/1] stp cost 20000
[*DeviceC-GigabitEthernet0/1/1] commit
[~DeviceC-GigabitEthernet0/1/1] quit
```
# On DeviceD, configure the path cost calculation method as the Huawei proprietary method.
```
[~DeviceD] stp pathcost-standard legacy
[*DeviceD] commit
```

Enable RSTP to eliminate loops.

Disable RSTP on interfaces connected to PCs.

# Disable RSTP on GE 0/1/2 on DeviceB.

[~DeviceB] interface gigabitethernet 0/1/2
[~DeviceB-GigabitEthernet0/1/2] stp disable
[*DeviceB-GigabitEthernet0/1/2] commit
[~DeviceB-GigabitEthernet0/1/2] quit

# Disable RSTP on GE 0/1/2 on DeviceC.

[~DeviceC] interface gigabitethernet 0/1/2
[~DeviceC-GigabitEthernet0/1/2] stp disable
[*DeviceC-GigabitEthernet0/1/2] commit
[~DeviceC-GigabitEthernet0/1/2] quit

Enable RSTP globally.

# Enable RSTP globally on DeviceA.

[~DeviceA] stp enable
[*DeviceA] commit

# Enable RSTP globally on DeviceB.

[~DeviceB] stp enable
[*DeviceB] commit

# Enable RSTP globally on DeviceC.

[~DeviceC] stp enable
[*DeviceC] commit

# Enable RSTP globally on DeviceD.

[~DeviceD] stp enable
[*DeviceD] commit

Enable RSTP on all the interfaces except the interfaces connected to terminals.

# Enable RSTP on GE 0/1/1 and GE 0/1/2 on DeviceA.

[~DeviceA] interface gigabitethernet 0/1/1
[~DeviceA-GigabitEthernet0/1/1] undo shutdown
[*DeviceA-GigabitEthernet0/1/1] portswitch
[*DeviceA-GigabitEthernet0/1/1] stp enable
[*DeviceA-GigabitEthernet0/1/1] quit
[*DeviceA] interface gigabitethernet 0/1/2
[*DeviceA-GigabitEthernet0/1/2] undo shutdown
[*DeviceA-GigabitEthernet0/1/2] portswitch
[*DeviceA-GigabitEthernet0/1/2] stp enable
[*DeviceA-GigabitEthernet0/1/2] commit
[~DeviceA-GigabitEthernet0/1/2] quit

# Enable RSTP on GE 0/1/1 and GE 0/1/3 on DeviceB.

[~DeviceB] interface gigabitethernet 0/1/1
[~DeviceB-GigabitEthernet0/1/1] undo shutdown
[*DeviceB-GigabitEthernet0/1/1] portswitch
[*DeviceB-GigabitEthernet0/1/1] stp enable
[*DeviceB-GigabitEthernet0/1/1] quit
[*DeviceB] interface gigabitethernet 0/1/3
[*DeviceB-GigabitEthernet0/1/3] undo shutdown
[*DeviceB-GigabitEthernet0/1/3] portswitch
[*DeviceB-GigabitEthernet0/1/3] stp enable
[*DeviceB-GigabitEthernet0/1/3] commit
[~DeviceB-GigabitEthernet0/1/3] quit

# Enable RSTP on GE 0/1/1 and GE 0/1/3 on DeviceC.

[~DeviceC] interface gigabitethernet 0/1/1
[~DeviceC-GigabitEthernet0/1/1] undo shutdown
[*DeviceC-GigabitEthernet0/1/1] portswitch
[*DeviceC-GigabitEthernet0/1/1] stp enable
[*DeviceC-GigabitEthernet0/1/1] quit
[*DeviceC] interface gigabitethernet 0/1/3
[*DeviceC-GigabitEthernet0/1/3] undo shutdown
[*DeviceC-GigabitEthernet0/1/3] portswitch
[*DeviceC-GigabitEthernet0/1/3] stp enable
[*DeviceC-GigabitEthernet0/1/3] commit
[~DeviceC-GigabitEthernet0/1/3] quit

# Enable RSTP on GE 0/1/1 and GE 0/1/2 on DeviceD.

[~DeviceD] interface gigabitethernet 0/1/1
[~DeviceD-GigabitEthernet0/1/1] undo shutdown
[*DeviceD-GigabitEthernet0/1/1] portswitch
[*DeviceD-GigabitEthernet0/1/1] stp enable
[*DeviceD-GigabitEthernet0/1/1] quit
[*DeviceD] interface gigabitethernet 0/1/2
[*DeviceD-GigabitEthernet0/1/2] undo shutdown
[*DeviceD-GigabitEthernet0/1/2] portswitch
[*DeviceD-GigabitEthernet0/1/2] stp enable
[*DeviceD-GigabitEthernet0/1/2] commit
[~DeviceD-GigabitEthernet0/1/2] quit

Configure RSTP protection functions, for example, root protection on a designated port of a root bridge in each MSTI.

# Enable root protection on GE 0/1/1 on DeviceA.

[~DeviceA] interface gigabitethernet 0/1/1
[*DeviceA-GigabitEthernet0/1/1] stp root-protection
[*DeviceA-GigabitEthernet0/1/1] commit
[~DeviceA-GigabitEthernet0/1/1] quit

# Enable root protection on GE 0/1/2 on DeviceA.

[~DeviceA] interface gigabitethernet 0/1/2
[*DeviceA-GigabitEthernet0/1/2] stp root-protection
[*DeviceA-GigabitEthernet0/1/2] commit
[~DeviceA-GigabitEthernet0/1/2] quit

Verify the configuration.

After the previous configurations, run the following commands to verify the configuration when the network is stable:

# Run the display stp brief command on DeviceA to view the interface status and protection type. The displayed information is as follows:

[~DeviceA] display stp brief
 MSTID  Port                        Role  STP State     Protection
   0    GigabitEthernet0/1/1        DESI  FORWARDING    ROOT
   0    GigabitEthernet0/1/2        DESI  FORWARDING    ROOT

After DeviceA is configured as a root bridge, GE 0/1/2 and GE 0/1/1 connected to DeviceB and DeviceD respectively are elected as designated ports in spanning tree calculation. The root protection function is enabled on the designated ports.

# Run the display stp interface gigabitethernet 0/1/1 brief command on DeviceB to view status of GE 0/1/1. The displayed information is as follows:

[~DeviceB] display stp interface gigabitethernet 0/1/1 brief
 MSTID  Port                        Role  STP State     Protection
   0    GigabitEthernet0/1/1        DESI  FORWARDING    NONE

GE 0/1/1 is elected as a designated port in spanning tree calculation and is in the Forwarding state.

# Run the display stp interface gigabitethernet 0/1/3 brief command on DeviceC to view status of GE 0/1/3. The displayed information is as follows:

[~DeviceC] display stp interface gigabitethernet 0/1/3 brief
 MSTID  Port                        Role  STP State     Protection
   0    GigabitEthernet0/1/3        ROOT  FORWARDING    NONE

GE 0/1/3 is elected as a designated port in spanning tree calculation and is in the Forwarding state.

# Run the display stp command on DeviceD to view the interface status and protection type. The displayed information is as follows:

[~DeviceD] display stp
-------[CIST Global Info][Mode RSTP]-------
CIST Bridge         :4096 .00e0-fc12-3456
Bridge Times        :Hello 2s MaxAge 20s FwDly 15s MaxHop 20
CIST Root/ERPC      :0    .00e0-fc12-3456 / 20000
CIST RegRoot/IRPC   :4096 .00e0-fc12-3456 / 0
CIST RootPortId     :128.1
BPDU-Protection     :Disabled
CIST Root Type      :SECONDARY root
TC or TCN received  :4
TC count per hello  :0
STP Converge Mode   :Normal
Time since last TC :0 days 0h:5m:44s
----[Port1(GigabitEthernet0/1/1)][FORWARDING]----
 Port Protocol       :enabled
 Port Role           :Root Port
 Port Priority       :128
 Port Cost(Dot1T )   :Config=auto / Active=20000
 Desg. Bridge/Port   :0.00e0-fc12-3456 / 128.1
 Port Edged          :Config=default / Active=disabled
 Point-to-point      :Config=auto / Active=true
 Transit Limit       :147 packets/hello-time
 Protection Type     :None
 Port Stp Mode       :RSTP
 Port Protocol Type  :Config=auto / Active=dot1s
 BPDU Encapsulation  :Config=stp / Active=stp
 PortTimes           :Hello 2s MaxAge 20s FwDly 15s RemHop 0
 TC or TCN send  :4
 TC or TCN received  :2
 BPDU Sent           :5
          TCN: 0, Config: 0, RST: 5, MST: 0
 BPDU Received       :177
          TCN: 0, Config: 0, RST: 177, MST: 0
----[Port2(GigabitEthernet0/1/2)][FORWARDING]----
 Port Protocol       :enabled
 Port Role           :Designated Port
 Port Priority       :128
 Port Cost(Dot1T )   :Config=auto / Active=20000
 Desg. Bridge/Port   :4096.00e0-fc12-3456 / 128.2
 Port Edged          :Config=default / Active=disabled
 Point-to-point      :Config=auto / Active=true
 Transit Limit       :147 packets/hello-time
 Protection Type     :None
 Port Stp Mode       :RSTP
 Port Protocol Type  :Config=auto / Active=dot1s
 BPDU Encapsulation  :Config=stp / Active=stp
 PortTimes           :Hello 2s MaxAge 20s FwDly 15s RemHop 20
 TC or TCN send  :2
 TC or TCN received  :2
 BPDU Sent           :165
          TCN: 0, Config: 0, RST: 165, MST: 0
 BPDU Received       :2
          TCN: 0, Config: 0, RST: 2, MST: 0

Configuration Files

Configuration file of DeviceA

#
 sysname DeviceA                                                                
#                                                                               
 stp mode rstp                                                                  
 stp instance 0 root primary                                                    
 stp pathcost-standard legacy                                                   
 stp enable                                                                     
#                                                                               
interface GigabitEthernet0/1/1                                                  
 portswitch
 undo shutdown
 stp root-protection                                                            
#                                                                               
interface GigabitEthernet0/1/2                                                  
 portswitch
 undo shutdown
 stp root-protection                                                            
#
return

Configuration file of DeviceB

#                                                                               
 sysname DeviceB                                                                
#                                                                               
 stp mode rstp                                                                  
 stp pathcost-standard legacy                                                   
 stp enable                                                                     
#                                                                               
interface GigabitEthernet0/1/1                                                  
 portswitch
 undo shutdown
 stp enable                                                            
#                                                                               
interface GigabitEthernet0/1/2                                                  
 stp disable                                                                    
#                                                                               
interface GigabitEthernet0/1/3                                                  
 portswitch
 undo shutdown
 stp enable                                                            
#                                                                               
return

Configuration file of DeviceC

#                                                                               
 sysname DeviceC                                                                
#                                                                               
 stp mode rstp                                                                  
 stp pathcost-standard legacy                                                   
 stp enable                                                                     
#                                                                               
interface GigabitEthernet0/1/1                                                  
 stp instance 0 cost 20000                                                      
 portswitch
 undo shutdown
 stp enable                                                            
#                                                                               
interface GigabitEthernet0/1/2                                                  
 stp disable                                                                    
#                                                                               
interface GigabitEthernet0/1/3                                                  
 portswitch
 undo shutdown
 stp enable                                                            
#                                                                               
return

Configuration file of DeviceD

#                                                                               
 sysname DeviceD                                                                
#                                                                               
 stp mode rstp                                                                  
 stp instance 0 root secondary                                                  
 stp pathcost-standard legacy                                                   
 stp enable                                                                     
#                                                                               
interface GigabitEthernet0/1/1                                                  
 undo shutdown
 portswitch
 stp enable                                                                     
#                                                                               
interface GigabitEthernet0/1/2                                                  
 undo shutdown
 portswitch
 stp enable                                                                     
#                                                                               
return