Unidirectional Link Detection: Difference between revisions

Revision as of 18:20, 5 March 2013

Revision as of 18:25, 5 March 2013

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==Description==

If two devices, A and B, are connected via a pair of [[optical fiber]]s, one used for sending from A to B and other for sending from B to A, the link is bidirectional (two-way). If one of these fibersfibres is broken, the link has become one-way or unidirectional. The goal of the UDLD protocol is to detect a broken bidirectional link (e.g. transmitted [[packet (information technology)|packets]] do not arrive at the receiver, or the fiberesfibres are connected to different [[computer port (hardware)|ports]]).

For each device and for each port, a UDLD packet is sent to the port it links to. The packet contains sender identity information (device and port), and expected receiver identity information (device and port). Each port checks that the UDLD packets it receives contain the identifiers of his own device and port.