3Com 3CRUS2475 User Manual page 319

318 A C: T
PPENDIX ROUBLESHOOTING
Problems
No connection and the
port LED is off
Possible Cause
Incorrect ethernet cable,
e.g., crossed rather than
straight cable, or vice
versa, split pair (incorrect
twisting of pairs)
Fiber optical cable
connection is reversed
Bad cable
Wrong cable type
Solution
Check pinout and replace if necessary
Change if necessary. Check Rx and Tx on fiber optic
cable
Replace with a tested cable
Verify that all 10 Mbps connections use a Cat 5 cable
Check the port LED or zoom screen in the NMS
application, and change setting if necessary