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Configuring Interfaces
Configuring Ethernet Interfaces
Entering the no port-type or default port-type interface configuration command returns the port to the default state:
UNI for Fast Ethernet ports and NNI for Gigabit Ethernet ports.
This example shows how to change a port from a UNI to an NNI and save it to the running configuration.
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface fastethernet0/1
Switch(config-if)# port-type nni
Switch(config-if)# no shutdown
5d20h: %SYS-5-CONFIG_I: Configured from console by console
Switch(config-if)# end
Switch# copy running-config startup-config
Configuring Interface Speed and Duplex Mode
Ethernet interfaces on the switch operate at 10, 100, or 1000 Mbps and in either full- or half-duplex mode. In full-duplex
mode, two stations can send and receive traffic at the same time. Normally, 10-Mbps ports operate in half-duplex mode,
which means that stations can either receive or send traffic.
Switch models include combinations of Fast Ethernet (10/100-Mbps) ports, Gigabit Ethernet (10/100/1000-Mbps) ports,
and small form-factor pluggable (SFP) module slots supporting SFP modules.
These sections describe how to configure the interface speed and duplex mode:
Speed and Duplex Configuration Guidelines, page 34
Setting the Interface Speed and Duplex Parameters, page 35
Speed and Duplex Configuration Guidelines
When configuring an interface speed and duplex mode, note these guidelines:
You can configure interface speed on Fast Ethernet (10/100-Mbps) and Gigabit Ethernet (10/100/1000-Mbps)
ports. You can configure Fast Ethernet ports to full-duplex, half-duplex, or to autonegotiate mode. You can configure
Gigabit Ethernet ports to full-duplex mode or to autonegotiate. You also can configure Gigabit Ethernet ports to
half-duplex mode if the speed is 10 or 100 Mbps. Half-duplex mode is not supported on Gigabit Ethernet ports
operating at 1000 Mbps.
With the exception of when 1000BASE-T SFP modules are installed in the SFP module slots, you cannot configure
speed on SFP module ports, but you can configure speed to not negotiate (nonegotiate) if connected to a device
that does not support autonegotiation.
However, when a 1000BASE-T SFP module is in the SFP module slot, you can configure speed as 10, 100, or 1000
Mbps, or auto, but not as nonegotiate.
Command Purpose
1. configure terminal Enter global configuration mode
2. interface interface-id Specify the interface to configure, and enter interface configuration mode.
3. no shutdown Enable the port, if necessary. By default, UNIs and ENIs are disabled, and
NNIs are enabled.
4. port-type {eni | nni | uni} Change a port to an ENI, NNI, or UNI.
5. end Return to privileged EXEC mode.
6. show interfaces interface-id Verify the interface 802.3x flow control settings.
7. copy running-config startup-config (Optional) Save your entries in the configuration file.
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