Cisco ME 1200 Series Hardware Installation Manual page 35

Troubleshooting
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Diagnosing Problems
The LEDs on the front panel provide troubleshooting information about the switch. They show power-on
self-test (POST) failures, port-connectivity problems, and overall switch performance. You can also get
statistics from the CLI on the UPE NID Controller. See the Cisco NID Controller guide on Cisco.com for
more information.
Switch Performance
Speed, Duplex, and Auto-negotiation
If the port statistics show a large amount of alignment errors, frame check sequence (FCS), or late-collisions
errors, this might mean a speed or duplex mismatch.
A common issue with speed and duplex is when the duplex settings are mismatched between two switches,
between a switch and a router, or between the switch and a workstation or server. Mismatches can happen
when manually setting the speed and duplex or from auto-negotiation issues between the two devices.
To maximize switch performance and to ensure a link, follow one of these guidelines when changing the
duplex or speed settings.
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OL-31962-04
Diagnosing Problems, page 4-1
Switch Performance, page 4-1
Finding the Switch Serial Number, page 4-2
Let both ports auto-negotiate both speed and duplex.
Manually set the speed and duplex parameters for the ports on both ends of the connection.
If a remote device does not auto-negotiate, set the same duplex settings on the two ports. The speed
parameter adjusts itself even if the connected port does not auto-negotiate.
Cisco ME 1200 Series Carrier Ethernet Access Devices Hardware Installation Guide
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C H A P T E R
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