Bridge Assurance

• Bridge Assurance is supported only by Rapid PVST+ and MST.

• Bridge Assurance is enabled only on spanning tree network ports that are point-to-point links.

• Both ends of the link must have Bridge Assurance enabled. If the device on one side of the link has Bridge Assurance enabled and the device on the other side either does not support Bridge Assurance or does not have this feature enabled, the connecting port is blocked.

• With Bridge Assurance enabled, BPDUs are sent out on all operational network ports, including alternate and backup ports, for each hello time period. If the port does not receive a BPDU for a specified period, the port moves into an inconsistent state (blocking). and is not used in the root port calculation. Once that port receives a BPDU, it resumes the normal spanning tree transitions.

# By default, Bridge Assurance is enabled on all network ports on the switch, if not, below command will enable it
Switch(config)# spanning-tree bridge assurance
# Configures the default state for all switch access ports to be network. Bridge Assurance will be enabled on all network access ports by default.
Switch(config-if)# spanning-tree portfast network