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---------- -------- ---- ------- --- ------- --------------------
Te 0/6 128.263 128
Te 0/7 128.264 128
Interface
Name
Role
PortID
---------- ------ -------- ---- ------- --- ----------------
Te 0/6 Root
128.263 128
Te 0/7 ErrDis 128.264 128
Dell(conf-if-te-0/7)#do show ip int br te 0/7
Interface
TenGigabitEthernet 0/7 unassigned YES Manual 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
Root Bridge hello time 2, max age 20, forward delay 15
Dell#
STP Root Guard
Use the STP root guard feature in a Layer 2 network to avoid bridging loops.
In STP, the switch in the network with the lowest priority (as determined by STP or set with the bridge-
priority command) is selected as the root bridge. If two switches have the same priority, the switch with
the lower MAC address is selected as the root. All other switches in the network use the root bridge as the
reference used to calculate the shortest forwarding path.
20000 FWD 20000 32768 0001.e805.fb07 128.653
20000 EDS 20000 32768 0001.e85d.0e90 128.264
Prio Cost
Sts Cost
20000 FWD 20000 P2P
20000 EDS 20000 P2P
IP-Address OK Method
Link-type Edge
No
No
Status Protocol
up
Spanning Tree Protocol (STP)
1085
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Troubleshooting
