Switch Performance
Speed, Duplex, and Autonegotiation
Port statistics that show a large number of alignment errors, frame check sequence (FCS), or late-collisions
errors, might mean a speed or duplex mismatch.
A common issue 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
parameter adjusts itself even if the connected port does not autonegotiate.
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 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 the 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. See the chapter
Reset the Switch
These are reasons why you might want to reset the switch to the factory default settings:
• You installed the switch in your network and cannot connect to it because you assigned the wrong IP
address.
• You want to reset the password on the switch.
Cisco Catalyst IE9300 Rugged Series Switch Hardware Installation Guide
66
Troubleshooting
Switch Performance
Summary of Contents for Catalyst IE-9310-26S2C-A
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