CLI Jockey

Unidirectional Link Detection (UDLD) is a Cisco proprietary extension that lives to detect miss-configured and broken links between Cisco switches. It verifies that they can both send and receive data on a point-to-point link. This can be used to assist spanning-tree and compliments things like ‘loop guard’ and ‘bridge assurance’ in your spanning-tree designs. Read more »

To prevent loops that might develop if a port that should be blocking transitions to the forwarding state we have loop guard. This could happen if a port stops receiving BPDUs, maybe due to a unidirectional (on point-to-point) link or software/configuration problem on the neighbour.

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