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1058 | Spanning Tree Protocol
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Figure 52-8 shows a scenario in which an edgeport might unintentionally receive a BPDU. The port on the
Dell Force10 system is configured with Portfast. If the switch is connected to the hub, the BPDUs that the
switch generates might trigger an undesirable topology change. If BPDU Guard is enabled, when the edge
port receives the BPDU, the BPDU will be dropped, the port will be blocked, and a console message will
be generated.
Message 1 BPDU Guard Error
3w3d0h: %RPM0-P:RP2 %SPANMGR-5-BPDU_GUARD_RX_ERROR: Received Spanning Tree BPDU on BPDU guard
port. Disable GigabitEthernet 3/41.
Note: Note that unless the shutdown-on-violation option is enabled, spanning-tree only drops packets
after a BPDU violation; the physical interface remains up, as shown below.
FTOS(conf-if-gi-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
---------- -------- ---- ------- --- ------- -------------------- --------
Gi 0/6 128.263 128 20000 FWD 20000 32768 0001.e805.fb07 128.653
Gi 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
---------- ------ -------- ---- ------- --- ------- --------- ----
Gi 0/6 Root 128.263 128 20000 FWD 20000 P2P No
Gi 0/7 ErrDis 128.264 128 20000 EDS 20000 P2P No
FTOS(conf-if-gi-0/7)#do show ip int br gi 0/7
Interface IP-Address OK Method Status Protocol
GigabitEthernet 0/7 unassigned YES Manual up up
FTOS Behavior: Regarding bpduguard shutdown-on-violation behavior:
1 If the interface to be shutdown is a port channel then all the member ports are disabled in the hardware.
2 When a physical port is added to a port channel already in error disable state, the new member port will
also be disabled in the hardware.
3 When a physical port is removed from a port channel in error disable state, the error disabled state is
cleared on this physical port (the physical port will be enabled in the hardware).
4 The reset linecard command does not clear the error disabled state of the port or the hardware disabled
state. The interface continues to be disables in the hardware.
The error disabled state can be cleared with any of the following methods:
•Perform an shutdown command on the interface.
•Disable the shutdown-on-violation command on the interface ( no spanning-tree stp-id portfast
[bpduguard | [shutdown-on-violation]] ).
•Disable spanning tree on the interface (no spanning-tree in INTERFACE mode).
•Disabling global spanning tree (no spanning-tree in CONFIGURATION mode).