STP configuration instance learning record

STP Configure the instance

STP（Spanning Tree Protocol） Is the English abbreviation of spanning tree protocol , It can be applied to the establishment of tree topology in computer network , The main function is to prevent redundant links in the bridge network from forming a loop .

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1、 The goal of the experiment

Master the switch STP Configuration of , Received relevant configuration commands

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2、 Network topology

notes ：PC Of IP Address 、 Subnet mask and gateway , Click on PC Enter self configuration

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3、 Configuration steps

（1） Turn on the switch STP function

Some devices may be turned on by default STP, So we can manually set STP close , An example of the close command is as follows ：

[SW1]undo stp enable  // close  STP

stay 3 Switch on STP function , And will STP The mode of is changed to 802.1D The standard STP

SW1：

<Huawei>system-view  // Enter the system view 
[Huawei]sysname SW1  // Rename the device 
[SW1]stp mode stp  // take  STP  The mode of is changed to  802.1D  The standard  STP 
[SW1]stp enable  // Turn on  STP

SW2：

<Huawei>system-view  // Enter the system view 
[Huawei]sysname SW2  // Rename the device 
[SW2]stp mode stp  // take  STP  The mode of is changed to  802.1D  The standard  STP 
[SW2]stp enable  // Turn on  STP 

SW3：

<Huawei>system-view  // Enter the system view  
[Huawei]sysname SW3  // Rename the device 
[SW3]stp mode stp  // take  STP  The mode of is changed to  802.1D  The standard  STP 
[SW3]stp enable  // Turn on  STP 

（2） Set switch priority

To configure SW1 The priority for 0,SW2 The priority for 4096

Method 1 ：

SW1：

[SW1]stp root primary  // The priority of configuring the switch is  0, That is, the highest priority 

SW2：

[SW2]stp root secondary  // The priority of configuring the switch is  4096, I.e. ratio  0  One level down  

Method 2 ：

SW1：

[SW1]stp priority 0  // The priority of configuring the switch is  0, That is, the highest priority 

SW2：

[SW2]stp priority 4096  // The priority of configuring the switch is  4096, I.e. ratio  0  One level down  

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4、 test

（1） Check whether the device trims the loop according to the configured parameters , Complete spanning tree

Observe PC1 and PC2 Interworking status of , If PC1 and PC2 Can communicate with each other , It means that the spanning tree has worked

use PC1 Go to ping PC2 Of IP Address , It is found that it can be connected

use PC2 Go to ping PC1 Of IP Address , I found that it can also pass

（2） Observe the operation of the spanning tree after the topology changes

notes ： There may be a small amount of packet loss

To break off SW1 and SW2 Post link observation PC1 and PC2 Interoperability of

use PC1 Go to ping PC2 Of IP Address , It can also be found that

use PC2 Go to ping PC1 Of IP Address , Discovery can also pass

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5、 Summary

STP Working process of ：

• Select root bridge （Root Bridge）： Root bridge , It's the root of the tree , It is the core of tree network .
• Select the root port （Root Port）： The root port is the port with the shortest path to the root bridge , The root port is responsible for forwarding data to the root bridge .
• Select the specified port （Designated Port）： The specified port is the port closest to the root on each network segment , It forwards the data sent to the network segment .
• Prepare blocking port （Alternate Port）： If a port is neither the root port nor the specified port , Is the preparatory port .

STP Port status of ：

Port status	describe	explain
Disabled Disabled state	The port in this state does not forward data frames , Don't work MAC Address table , Do not participate in spanning tree calculation	The port status is Down
Listening Listening state	The port in this state does not forward data frames , Don't work MAC Address table , Only participate in spanning tree calculation , Receive and send BPDU	Transition state , increase Learning Status can prevent temporary loops
Blocking Blocked state	The port in this state does not forward data frames , Don't work MAC Address table , receive BPDU, But don't send it out BPDU	The final state of the blocking port
Learning Learning state	The port in this state does not forward data frames , But learning MAC Address table , Participate in spanning tree calculation , Receive and send BPDU	Transition state
Forwarding Forwarding status	The port in this state forwards data frames normally , Study MAC Address table , Participate in spanning tree calculation , Receive and send BPDU	Only the root port and the specified port can enter Forwarding state

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If there are mistakes in the article , Welcome to criticize and correct