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• disables spanning tree on an interface
• drops all BPDUs at the line card without generating a console message
Example of Blocked BPDUs
Dell(conf-if-te-0/7)#do show spanning-tree rstp brief
Executing IEEE compatible Spanning Tree Protocol
Root ID Priority 32768, Address 0001.e805.fb07
Root Bridge hello time 2, max age 20, forward delay 15
Bridge ID Priority 32768, Address 0001.e85d.0e90
Configured hello time 2, max age 20, forward delay 15
Interface Designated
Name PortID Prio Cost Sts Cost Bridge ID PortID
---------- -------- ---- ------- --- ------- --------------------
Te 0/6 128.263 128 20000 FWD 20000 32768 0001.e805.fb07 128.653
Te 0/7 128.264 128 20000
EDS 20000 32768 0001.e85d.0e90 128.264
Interface
Name Role PortID Prio Cost Sts Cost Link-type Edge
---------- ------ -------- ---- ------- --- ----------------
Te 0/6 Root 128.263 128 20000 FWD 20000 P2P No
Te 0/7
ErrDis 128.264 128 20000 EDS 20000 P2P No
Dell(conf-if-te-0/7)#do show ip int br te 0/7
Interface IP-Address OK Method Status Protocol
TenGigabitEthernet 0/7 unassigned YES Manual up
up
Selecting STP Root
The STP determines the root bridge, but you can assign one bridge a lower priority to increase the
likelihood that it becomes the root bridge. You can also specify that a bridge is the root or the secondary
root.
To change the bridge priority or specify that a bridge is the root or secondary root, use the following
command.
• Assign a number as the bridge priority or designate it as the root or secondary root.
PROTOCOL SPANNING TREE mode
bridge-priority {priority-value | primary | secondary}
– priority-value: the range is from 0 to 65535. The lower the number assigned, the more likely
this bridge becomes the root bridge.
The primary option specifies a bridge priority of 8192.
The secondary option specifies a bridge priority of 16384.
The default is 32768.
Example of Viewing STP Root Information
To view only the root information, use the show spanning-tree root command from EXEC privilege
mode.
Dell#show spanning-tree 0 root
Root ID Priority 32768, Address 0001.e80d.2462
We are the root of the spanning tree
878
Spanning Tree Protocol (STP)