Connectivity Guide

spanning-tree guard loop command. After BPDUs are received, the port moves out of the Loop-
Inconsistent or blocking state and transitions to an appropriate state determined by STP. Enabling loop guard on a
per port basis enables it on all VLANs congured on the port. If you disable loop guard on a port, it is moved to the
Listening state.
If you enable BPDU Filter and BPDU Guard on the same port, the BPDU Filter conguration takes precedence. Root Guard and Loop Guard
are mutually exclusive. Conguring one overwrites the other from the active conguration.
• Enable spanning-tree BPDU lter in INTERFACE mode. Use the spanning-tree bpdufilter disable command to disable the
BPDU lter on the interface.
spanning-tree bpdufilter enable
• Enable spanning-tree BPDU guard in INTERFACE mode.
spanning-tree bpduguard enable
– Use the shutdown command to shut down the port channel interface, all member ports that are disabled in the hardware.
– Use the spanning-tree bpduguard disable command to add a physical port to a port-channel already in the Error Disable
state, the new member port is also disabled in the hardware.
• Set the guard types to avoid loops in INTERFACE mode.
spanning-tree guard {loop | root | none}
– loop — Set the guard type to loop.
– none — Set the guard type to none.
–
root — Set the guard type to root.
BPDU lter
OS10(conf-if-eth1/1/4)# spanning-tree bpdufilter enable
OS10(conf-if-eth1/1/4)# do show spanning-tree interface ethernet 1/1/4
ethernet1/1/4 of vlan1 is designated Blocking
Edge port:no (default) port guard :none (default)
Link type is point-to-point (auto)
Boundary: NO bpdu filter : Enable bpdu guard : bpduguard shutdown-on-
violation :disable RootGuard: enable LoopGuard disable
Bpdus (MRecords) sent 134, received 138
Interface Designated
Name PortID Prio Cost Sts Cost Bridge ID PortID
--------------------------------------------------------------------------
ethernet1/1/4 128.272 128 500 BLK 500 32769 90b1.1cf4.a911 128.272
BPDU guard
OS10(config)# interface ethernet 1/1/4
OS10(conf-if-eth1/1/4)# spanning-tree bpduguard enable
OS10(conf-if-eth1/1/4)# exit
OS10(config)# interface ethernet 1/1/4
OS10(conf-if-eth1/1/4)# do show spanning-tree interface ethernet 1/1/4
ethernet1/1/4 of vlan1 is designated Blocking
Edge port:no (default) port guard :none (default)
Link type is point-to-point (auto)
Boundary: NO bpdu filter : Enable bpdu guard : bpduguard shutdown-on-
violation :enable RootGuard: enable LoopGuard disable
Bpdus (MRecords) sent 134, received 138
Interface Designated
Name PortID Prio Cost Sts Cost Bridge ID PortID
------------------------------------------------------------------
ethernet1/1/4 128.272 128 500 BLK 500 32769 90b1.1cf4.a911 128.272
Loop guard
OS10(config)# interface ethernet 1/1/4
OS10(conf-if-eth1/1/4)# spanning-tree guard loop
OS10(conf-if-eth1/1/4)# do show spanning-tree interface ethernet 1/1/4
ethernet1/1/4 of vlan1 is root Forwarding
Edge port:no (default) port guard :none (default)
Link type is point-to-point (auto)
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Layer 2