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7.5 MSTP Troubleshooting
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In order to run the MSTP on the switch port, the MSTP has to be enabled globally. If
the MSTP is not enabled globally, it can’t be enabled on the port.
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The MSTP parameters co work with each other, so the parameters should meet the
following conditions. Otherwise, the MSTP may work incorrectly.
2×(Bridge_Forward_Delay -1.0 seconds) >= Bridge_Max_Age
Bridge_Max_Age >= 2 ×(Bridge_Hell 1.0 seconds)
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When users modify the MSTP parameters, they have to be sure about the changes
of the topologies. The global configuration is based on the bridge. Other
configurations are based on the individual instances.
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The MSTP are mutually exclusive with MAC binding and IEEE 802.1x on the switch
port. If MAC binding or IEEE 802.1x is enabled on the port, the MSTP can’t apply to
this port.
7.5.1 Commands for Monitor And Debug
7.5.1.1 show spanning-tree
Command: show spanning-tree [mst [<instance-id>]] [interface <interface-list>]
[detail]
Function:
Display the MSTP Information.
Parameter: <instance-id>
sets the instance ID. The valid range is from 0 to 48;
<interface-list>
sets interface list;
detail
sets the detailed spanning-tree information.
Command mode:
Admin Mode
Usage Guide:
This command can display the MSTP information of the instances in the
current bridge.
Example:
Display the bridge MSTP.
Switch#sh spanning-tree
-- MSTP Bridge Config Info --
Standard : IEEE 802.1s
Bridge MAC : 00: 03: 0f: 01: 0e: 30
Bridge Times : Max Age 20, Hello Time 2, Forward Delay 15
Force Version: 3
########################### Instance 0 ###########################
Self Bridge Id : 32768 - 00: 03: 0f: 01: 0e: 30
Root Id : 16384.00: 03: 0f: 01: 0f: 52
