Serial of H3CNE experiment column - spanning tree STP configuration experiment

What I bring to you today is h3cne Spanning tree in experiment STP experiment , Please look at the catalogue ：

• One 、 Experiment contents and objectives
• Two 、 Experimental networking diagram
• 3、 ... and 、 Experimental process
  • 3.1 Experiment task one ：STP Basic configuration
• 3、 ... and 、 List of commands in the experiment
• Four 、 Thinking questions

One 、 Experiment contents and objectives

Complete this experiment , You should be able to ：

• understand STP How it works
• master STP The basic configuration of

Two 、 Experimental networking diagram

STP Experimental networking diagram

3、 ... and 、 Experimental process

3.1 Experiment task one ：STP Basic configuration

This experiment is done by configuring STP Root bridge and edge port , So that we can master STP Configuration commands and viewing methods of root bridge and edge port . Then observe the port state migration , To deepen our understanding RSTP/MSTP Fast convergence of the protocol .

Step one ： Establish a physical connection

According to the plan STP Connect the experimental network diagram , Check the software version and configuration information of the equipment , Ensure that the software version of each device meets the requirements , All configurations are in the initial state . If the configuration does not meet the requirements , Please erase the configuration file in the device in user mode , Then restart the device to initialize the system with default configuration parameters .

The above steps may use the following commands ：

<SWA> display version
<SWA> reset saved-configuration
<SWA> reboot

“ Be careful ： If the physical connection is established , Ports on the switch panel LED Keep blinking , And Console The port does not respond to the configuration command , It is likely that the broadcast storm caused . If so , Please disconnect the cables between switches , Connect after configuration . ”

Step two ： To configure STP

The task of this experiment is to configure STP Root bridge and edge port . Enable... In the system view STP, And set up SWA The priority of 0, In order to make SWA Is the root bridge ; And configure the connection PC The port of is edge port .

To configure SWA：

[SWA]stp global enable
[SWA]stp priority 0
[SWA]interface GigabitEthernet 1/0/1
[SWA-GigabitEthernet1/0/1] stp edged-port

To configure SWB：

[SWB]stp global enable
[SWB]stp priority 4096
[SWB]interface GigabitEthernet 1/0/1
[SWB-GigabitEthernet1/0/1] stp edged-port

Step three ： see STP Information

Respectively in SWA and SWB Check out STP Information . The correct information should be as follows ：

[SWA]display stp
-------[CIST Global Info][Mode MSTP]-------
CIST Bridge :0.000f-e24a-df50
Bridge Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20
CIST Root/ERPC :0.000f-e24a-df50 / 0
CIST RegRoot/IRPC :0.000f-e24a-df50 / 0
……
[SWA]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet1/0/1 DESI FORWARDING NONE
0 GigabitEthernet1/0/23 DESI FORWARDING NONE
0 GigabitEthernet1/0/24 DESI FORWARDING NONE

The above information shows that ,SWA It's the root bridge , All ports on it are designated ports （DESI）, In forwarding state .

[SWB]display stp
-------[CIST Global Info][Mode MSTP]-------
CIST Bridge :4096.000f-e23e-f9b0
Bridge Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20
CIST Root/ERPC :0.000f-e24a-df50 / 200
CIST RegRoot/IRPC :4096.000f-e23e-f9b0 / 0
……
[SWB]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet1/0/1 DESI FORWARDING NONE
0 GigabitEthernet1/0/23 ROOT FORWARDING NONE
0 GigabitEthernet1/0/24 ALTE DISCARDING NONE

The above information shows that ,SWB Right and wrong root bridge , port G1/0/23 Is the root port , In forwarding state , Responsible for forwarding data between switches ; port G1/0/24 Is the backup root port , In a blocking state ; Connect PC The port of G1/0/1 Is the specified port , In forwarding state .

Step four ：STP Verification of redundancy characteristics

STP It can not only block redundant links , And when the active link is disconnected , Restore network connectivity by activating blocked redundant links .

IP Address list :

Equipment name	IP Address	gateway
PCA	172.16.0.1/24	--
PCB	172.16.0.2/24	--

As shown in the above table PC On the configuration IP Address .

When the configuration is complete , stay PCA Carry out the order “Ping 172.16.0.2 –t”, In order to make PCA towards PCB Send continuously ICMP message . As shown below ：

stay SWB Check out STP Port status , Determine which port between switches （ In this case, it is G1/0/23） In forwarding state . Place the switches between STP The cable on the port in forwarding status is disconnected , Observe PCA Sent on ICMP Whether the message is lost . Under normal circumstances , There should be no message lost or only one message lost .

Again in SWB Check out STP Port status , Check whether the port status changes . As shown below ：

You can see , The port that was originally blocked G1/0/24 Migrated to forwarding status .

No message loss indicates that at present STP The rate of convergence is very fast . Actually , This is it. RSTP/MSTP be relative to STP One of the improvements of . By default , Switch operation MSTP,SWB One of the two ports on is the root port , The other is the backup root port . When the original root port is disconnected , The backup root port quickly switches to the forwarding state .

“ Be careful ： If in PCA On Ping 172.16.0.2 –t When “Request timed out.”, indicate PCB No response , Need to check PCB Whether the firewall is enabled or whether there is a problem with the switch configuration . ”

Step five ： View port status migration

At the switch SWA Disconnect the port from the G1/0/1 The cable , Reconnect , And in SWA View switch output information on the . as follows ：

[SWA]
……
GigabitEthernet1/0/1: link status is UP
%Apr 26 14:04:53:880 2000 SWA MSTP/2/PFWD:Instance 0's GigabitEthernet1/0/1 has
been set to forwarding state!

You can see , The port becomes the forwarding state immediately after connecting the cable . This is because the port is configured as an edge port , Enter forwarding state without delay . This is also RSTP/MSTP be relative to STP One of the improvements of .

In the previous experiment , Fast port state migration . In order to clearly observe the port status , We're connecting PC The port of G1/0/1 Cancel edge port configuration on , as follows ：

To configure SWA：

[SWA]interface GigabitEthernet 1/0/1
[SWA-GigabitEthernet1/0/1] undo stp edged-port

When the configuration is complete , Disconnect the port G1/0/1 The cable , Reconnect , And in SWA View port on G1/0/1 The state of . Note that the command is executed every few seconds to view , To accurately see the migration process of the port state . for example ：

[SWA]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet1/0/1 DESI DISCARDING NONE
0 GigabitEthernet1/0/24 DESI FORWARDING NONE
[SWA]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet1/0/1 DESI LEARNING NONE
0 GigabitEthernet1/0/24 DESI FORWARDING NONE
[SWA]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet1/0/1 DESI LEARNING NONE
0 GigabitEthernet1/0/24 DESI FORWARDING NONE
……
#Apr 26 14:02:24:934 2000 SWA MSTP/1/PFWD:hwPortMstiStateForwarding: Instance 0's
Port 0.9371648 has been set to forwarding state!
%Apr 26 14:02:24:940 2000 SWA MSTP/2/PFWD:Instance 0's GigabitEthernet1/0/1 has
been set to forwarding state!
MSTID Port Role STP State Protection
0 GigabitEthernet1/0/1 DESI FORWARDING NONE
0 GigabitEthernet1/0/24 DESI FORWARDING NONE

You know , Port from Discarding The state first migrates to Learning state , The last to Forwarding state . From the above experiments we can see that , After canceling the edge port configuration ,STP The rate of convergence slows down .

3、 ... and 、 List of commands in the experiment

STP List of experimental commands :

command	describe
stp global enable	Turn on or off global or port STP characteristic
stp mode { mstp	pvst
stp [ instance instance-list	vlan vlan-id-list ] priority priority
stp edged-port	Configure the current Ethernet port as an edge port
display stp [ instance instance-list	vlan vlan-id-list ] [ interface interface-list

Four 、 Thinking questions

In the experiments , Switch SWB Select port G1/0/23 As the root port , Forward data . Can I make the switch choose another port G1/0/24 As the root port ？

answer ： Sure . By default , Port of Cost The value is 200（100M The default value of the port ）, If you adjust the port G1/0/24 Of Cost The value is 100,SWB From port G1/0/24 arrive SWA The cost of is less than that of the slave port G1/0/23 arrive SWA The cost of , be STP Will select the port G1/0/24 As the root port .