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Revision 7 as of 2008-04-18 15:33:53
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Editor: 151
Comment: update udld draft version
Revision 8 as of 2008-04-23 08:50:40
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Editor: 151
Comment:
Deletions are marked like this. Additions are marked like this.
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 * [[http://www.ietf.org/internet-drafts/draft-foschiano-udld-03.txt|draft-foschiano-udld-03.txt]] ''!UniDirectional Link Detection (UDLD) Protocol '' - Draft specification for the UDLD protocol  * [[http://www.tools.ietf.org/rfc/rfc5171.txt|RFC 5171]] Informational !UniDirectional Link Detection (UDLD) Protocol RFC

UniDirectional Link Detection (UDLD)

UDLD is a Cisco Layer 2 protocol to detect a uni-directional fiber link between two Ethernet switches in order to prevent a looped network. UDLD is often used in switched Ethernet networks where Spanning-Tree is required to block one or more ports to prevent a loop from forming.

History

UDLD was originally developed for the Cisco Catalyst 5000 series switches.

Protocol dependencies

  • Ethernet: UDLD uses Ethernet as its transport protocol using destination mac address 0100.0CCC.CCCC.

Example traffic

Wireshark

UDLD support was added in Wireshark 0.99.4.

Preference Settings

There are no preference settings at the present time.

Example capture file

* SampleCaptures/udld.pcap

Display Filter

Show only UDLD packets:

  udld 

A complete list of display filters can be found in the Display Filter Reference.

Capture Filter

You cannot directly filter UDLD protocols while capturing. However, if you use the Ethernet destination MAC address (see above), you can filter on that one:

  ether dst 01:00:0c:cc:cc:cc 

  • RFC 5171 Informational UniDirectional Link Detection (UDLD) Protocol RFC

Discussion

The originally stated sample capture was void, so please add the udld.pcap capture to the SampleCaptures page.

UDLD (last edited 2008-04-23 08:50:40 by 151)