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Cisco ME 3400 Ethernet Access Switch Hardware Installation Guide
OL-7677-04
Chapter3 Troubleshooting
How to Clear the Switch IP Address and Configuration
Check Switch Performance
Review this section when you troubleshoot switch 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 and a router, or between the switch 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 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 NIC Cards
Problems sometimes occur between the switch and third-party network interface cards (NICs). By
default, the switch 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 autonegotation 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 card might be causing the problem.
Upgrade the NIC card 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 to the connected device meets the recommended guidelines. See the “Cable and Adapter
Specifications” section on page A-4 for cabling guidelines.
How to Clear the Switch IP Address and Configuration
This section describes how to reset the switch by rerunning the initial configuration dialog (system
configuration dialog). These are reasons why you might want to reset the switch:
• You installed the switch in your network and cannot connect to it because you assigned the wrong
IP address.
• You want to clear all the configuration settings from the switch and assign a new IP address.