Cable Diagnostics For "E" Series Switches - Extreme Networks ExtremeWare Version 7.8 Troubleshooting Manual

Extended Cable Status Information (Gigabit link established). When the Gigabit link can be
established, the CDM tests report additional status information on approximate cable length, pair skew,
polarity swap, and pair swap.
• Cable length—After link, the cable diagnostics use a non-TDR method to determine and report the
approximate cable length between the near-end port and its far-end link partner.
• Pair skew—The cable diagnostics can detect skew among the four pairs of the cable that connects
the near-end port to its far-end link partner. Three of the four pairs report their delay skew with
respect to the fastest pair in increments of 8 nanosecond (ns).
• Polarity swap—The cable diagnostics can detect and report when any of the cable pairs connected to
the PHY was inverted.
• Pair swap—The cable diagnostics can detect when the auto-crossover capability of the port's PHY
has adjusted the role of its MDI pairs in the process of establishing link to its link partner. The cable
diagnostics report the channels associated with the MDI pairs.
Cable Diagnostics for " e " Series Switches
If you are having a problem establishing a link, you might have a faulty Ethernet cable. An Ethernet
cable is composed of four pairs of unshielded twisted-pair (UTP) conductors. Of those four pairs, two
pairs are required to create the link. In addition to checking the cable visually, you can also run a CLI
command to test the cable.
To test an Ethernet cable connected to an "e" series switch, use this command:
run diagnostics cable ports <portlist>
This command tests each of the four unshielded twisted pair (UTP) wire pairs. When the test ends, it
displays a message prompting you to enter the
the cable diagnostic test results.
To display the output of the cable diagnostic test on an "e" series switch, use this command:
show ports <portlist> cable diagnostics
Advanced System Diagnostics and Troubleshooting Guide
show ports cable diagnostics
Cable Diagnostics
command to display
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