DULD-MIB

Description: Covers Unidirectional Link Detection (DULD), used to detect one-way fiber links on network switches and shut them down.

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DULD-MIB is a private enterprise MIB implementing Unidirectional Link Detection functionality on network switches, used to identify fiber-optic links that are only passing traffic in one direction (a common cause of spanning-tree loops and silent link failures) and to automatically disable them. It exposes configuration and status data for DULD-monitored ports, including whether DULD detection is enabled and the detected link direction/fault state per port. Its role is squarely fault detection for network links: it flags ports where a mismatched transmit/receive fiber pair or a failed transceiver has created a one-way link, and reports whether the switch has automatically shut the port down in response, directly protecting network stability against loop-inducing hardware faults. It complements standard link-layer discovery/loop-protection mechanisms (such as UDLD-style protocols) though it is a proprietary implementation rather than a standards-based one. It is deployed on enterprise and data-center switches using fiber uplinks where undetected one-way links pose a network stability risk. Engineers implementing or auditing this functionality typically reference the DULD-MIB RFC/standard documentation for the authoritative specification.

An administrator would poll the DULD status table per port to see whether unidirectional link detection is enabled and whether a given port has been flagged as detecting a one-way link condition. A port reporting a bidirectional-mismatch fault state combined with an automatic port-disable action indicates a bad fiber strand or failing transceiver has been isolated before it could cause a spanning-tree loop. Since exact object names were not supplied in this source, table/column names above are described generically based on the module's stated purpose rather than cited literally.

Manages Unidirectional Link Detection (DULD) to identify and disable one-way fiber links on network switches.