Setup Guide

is placed in an Error Disabled state when receiving the BPDU, the physical interface remains up and spanning-tree will only drop
packets after a BPDU violation.
The following example shows a scenario in which an edgeport might unintentionally receive a BPDU. The port on the Dell EMC
Networking 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 you enable BPDU Guard, when the edge port receives the BPDU, the BPDU is
dropped, the port is blocked, and a console message is generated.
NOTE: Unless you enable the shutdown-on-violation option, spanning-tree only drops packets after a BPDU
violation; the physical interface remains up.
Dell EMC Networking OS Behavior: Regarding bpduguard shutdown-on-violation behavior:
● If the interface to be shut down is a port channel, all the member ports are disabled in the hardware.
● When you add a physical port to a port channel already in the Error Disable state, the new member port is also disabled in the
hardware.
● When you remove a physical port from a port channel in the Error Disable state, the Error Disabled state is cleared on this
physical port (the physical port is enabled in the hardware).
● You can clear the Error Disabled state with any of the following methods:
○ Perform a shutdown command on the interface.
○ Disable the shutdown-on-violation command on the interface (the no spanning-tree stp-id portfast
[bpduguard | [shutdown-on-violation]] command).
○ Disable spanning tree on the interface (the no spanning-tree command in INTERFACE mode).
○ Disabling global spanning tree (the no spanning-tree in CONFIGURATION mode).
Figure 118. Enabling BPDU Guard
Dell EMC Networking OS Behavior: BPDU guard and BPDU filtering both block BPDUs, but are two separate features.
BPDU guard:
● is used on edgeports and blocks all traffic on edgeport if it receives a BPDU.
● drops the BPDU after it reaches the RP and generates a console message.
BPDU filtering:
● disables spanning tree on an interface
● drops all BPDUs at the line card without generating a console message
Spanning Tree Protocol (STP)
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