RFC 5171

Cisco Systems UniDirectional Link Detection (UDLD) Protocol, April 2008

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M. Foschiano

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DOI:  10.17487/RFC5171

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This document describes a Cisco Systems protocol that can be used to detect and disable unidirectional Ethernet fiber or copper links caused, for instance, by mis-wiring of fiber strands, interface malfunctions, media converters' faults, etc. It operates at Layer 2 in conjunction with IEEE 802.3's existing Layer 1 fault detection mechanisms.

This document explains the protocol objectives and applications, illustrates the specific premises the protocol was based upon, and describes the protocol architecture and related deployment issues to serve as a possible base for future standardization. This memo provides information for the Internet community.

For the definition of Status, see RFC 2026.

For the definition of Stream, see RFC 4844.

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