Sunday, December 4, 2011

BPDU Guard, BPDU Filter, Root Guard, Loop Guard and UDLD

BPDU Guard
A switch port with PortFast configured detects and shuts down the switch port if it detects an incoming BPDU frame

BPDU Filter
A switch port with PortFast configured detects and ignores the switch port if there is incoming BPDU frame to the switch port

Unlike BPDU Guard feature, BPDU Filter feature does not shutdown the switch port. However you may need to reset the switch ports (issue shut and no shut on the switch port) in order to "revive" the switch port condition after BPDU frame is received on such switch port.

Root Guard
A switch port configured with Root Guard will never become a Root Port. You might need this feature when the switch port should never become a Root Port, for example when a switch port connects to host or edge port, or possibly a switch port with low bandwidth.

Loop Guard and UDLD
As the name implies, Loop Guard feature sets the switch port to detect potential loop due to inactive UDLD.

More Info: Spanning-Tree Protocol Enhancements using Loop Guard and BPDU Skew Detection Features

More Info: Loop Guard versus UDLD

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