Switch Performance; Speed, Duplex, And Autonegotiation; Autonegotiation And Network Interface Cards; Cabling Distance - Cisco Catalyst 2960-L Smart Managed Series Hardware Installation Manual

Switch Performance

Switch Performance

Speed, Duplex, and Autonegotiation

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 occurs when duplex and speed 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 autonegotiation issues between the two devices.
To maximize switch performance and to ensure a link, follow one of these guidelines when changing the
duplex or the speed settings.
• Let both ports autonegotiate both speed and duplex.
• Manually set the speed and duplex parameters for the interfaces on both ends of the connection.
• If a remote device does not autonegotiate, use the same duplex settings on the two ports. The speed

Autonegotiation and Network Interface Cards

Problems sometimes occur between the switch and third-party network interface cards (NICs). By default,
the switch ports and interfaces autonegotiate. Laptops or other devices are commonly 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, there could be a problem with the firmware or software on your NIC. You can resolve this
by upgrading the NIC driver to the latest version.

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.

Finding the Switch Serial Number

If you contact Cisco Technical Assistance, you need to know the switch serial number. You can also use the
show version privileged EXEC command to see the switch serial number.
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parameter adjusts itself even if the connected port does not autonegotiate.
Troubleshooting