
Chapter3 Troubleshooting
Diagnosing Problems
3-4
Catalyst 3550 Multilayer Switch Hardware Installation Guide
78-11358-03
No connectivity Incorrect or bad cable
The following are results of no link
at both ends:
• A crossover cable was used
when a straight-through was
required, or vice-versa.
• The cable is wired incorrectly.
• A crossover or straight-through
cable is wired incorrectly.
• STP checking for possible
loops.
• For the correct pinouts and
the proper application of
crossover vs.
straight-through cables, see
the “Two Twisted-Pair
Cable Pinouts” section on
page B-7.
• Replace with a tested good
cable.
• For 1000BASE-T
connections, be sure to use
a twisted four-pair,
Category 5 cable.
• Wait 30 seconds for the port
LED to turn green.
Switch not recognizing a GBIC
module.
Refer to the your GBIC
documentation for more
information.
Unreadable characters on the
management console
Incorrect baud rate. Reset the emulation software to
9600 baud.
Table 3-2 Common Problems and Their Solutions (continued)
Symptom Possible Cause Resolution
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