Cisco 3550 User Manual
Page 54
3-4
Catalyst 3550 Switch Hardware Installation Guide
OL-6155-01
Chapter 3 Troubleshooting
Diagnosing Problems
No connectivity
•
Verify that the devices at both ends of the link are connected
and powered.
•
Verify that the autonegotiation settings are the same at both
ends.
•
Verify that you are using the appropriate Ethernet cable for the
connected device. See
for cabling
requirements.
•
Verify that the cable is good by testing it on another device.
Replace it with a known working cable.
•
STP might be checking for possible loops. Wait 30 seconds for
the port LED to turn green.
•
For 1000BASE-T connections, make sure to use a twisted
four-pair, Category 5 cable.
•
The switch is not recognizing a GBIC module. See the
Module Slots” section on page 1-6
for Cisco-recommended
GBIC modules, and see your GBIC module documentation for
more information.
Poor performance or excessive
errors
•
There might be a speed and duplex autonegotiation mismatch.
Use the show controllers ethernet-controller privileged
EXEC command to display per-port send and receive statistics
read from the hardware. You can also use the show interfaces
privileged EXEC command to display the administrative and
operational status of all ports or a specified port.
•
The cabling distance might be exceeded. Reduce the cable
length to within the distances listed in the
Description” section on page 1-4
Table 3-1
Common Problems and Solutions (continued)
Problem
Solution