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Cisco Catalyst Blade Switch 3120 for HP Hardware Installation Guide
OL-12246-01
Chapter 3 Troubleshooting
Diagnosing Problems
Verify the Switch Module Performance
Review this section when you troubleshoot switch module performance problems.
Speed, Duplex, and Autonegotiation
If the port statistics show a large number of alignment errors, frame check sequence (FCS), or
late-collisions errors, a speed or duplex mismatch might be the problem.
A common issue with speed and duplex occurs when the duplex settings are mismatched between two
switches, between a switch module and a router, or between the switch module and a workstation or
server. This can happen when you manually set the speed and duplex or because of autonegotiation
issues between the two devices.
These circumstances can result in a mismatch:
• A manually set speed or duplex parameter is different from the manually set speed or duplex
parameter on the connected port.
• A port is set to autonegotiate, and the connected port is set to full duplex with no autonegotiation.
To maximize switch module performance and ensure a link, follow one of these guidelines when you set
or change the settings for duplex and speed:
• Let both ports autonegotiate 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 autonegotiate, configure the duplex settings on the two ports to match.
The speed parameter can adjust itself even if the connected port does not autonegotiate.
Autonegotiation and Network-Interface Cards
Problems sometimes occur between the switch module and third-party network-interface cards (NICs).
By default, the switch module ports and interfaces are set to autonegotiate. It is common for devices such
as laptop computers or other devices to also be set to autonegotiate, yet sometimes autonegotiation issues
occur.
To troubleshoot autonegotiation problems, try manually setting both sides of the connection. If this does
not solve the problem, the firmware or software on your NIC might be causing the problem. Upgrade the
NIC driver to the latest version available from the manufacturer.
Cabling Distance
If the port statistics show excessive FCS, late-collision, or alignment errors, verify that the cable distance
from the switch module to the connected device meets the recommended guidelines. See the
“Cable and
Adapter Specifications” section on page B-4 for cabling guidelines.