Looking into a complaint where an AP keeps going offline (orange LED) on an EXOS switch. The port is running at 100 Mbps instead of 1000 Mbps.
Suspect a cabling issue could be the cause but how can I prove this?
Found a useful command to check the cable (can be used on a single port) from the command line which has highlighted there could be an issue with one of the pairs. The test runs for 30 seconds. It will impact traffic on the selected port during the test.
Slot-1 Switch1 #% run diagnostics cable ports 1:18
Do you want to continue cable diagnostics? (y/N) Yes
cablediag: 1.1.0.14
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C A U T I O N +
cablediag will momentarily interfere with traffic on active ports +
+———————————————————————–+
Slot 1: Ports: 18 +
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Collecting port cable diagnostic information may take a moment…
Slot 1
port 1:18: cable (4 pairs, length +/- 10 meters)
pair A Ok, length 31 meters
pair B Open, length 26 meters
pair C Ok, length 26 meters
pair D Ok, length 23 meters
If the diagnostic test reports that Pair B is open, it means there’s a break or disconnection in the second pair of wires inside the Ethernet cable — and this directly explains why we are only getting 100 Mbps instead of 1000 Mbps (and a possible cause of AP instability).