Configuration of Switchports at the Physical layer
Switch ports can be manually configured with custom duplex and speed settings.
The duplex interface configuration mode command will allow you to manually specify the duplex mode for a switch port.
The speed interface configuration mode command will allow you to manually specify the speed.
In modern networking, usually devices should always operate in full-duplex at 1Gbps.
Configuring Auto Duplex and Speed settings on Switchports
Enter Global Configuration Mode
s1> enable S1# configure terminal
Enter interface configuration mode
S1(config)# interface [interface-id]
Configure the interface Duplex
S1(config-if)# duplex [mode]
Configure the interface Speed
S1(config-if)# speed [speed]
Switchport Duplex and Speed Configuration Example
s1> enable S1# configure terminal S1(config)# interface fa0/1 S1(config-if)# duplex auto S1(config-if)# speed 1000 S1(config-if)# exit S1(config)#
[NOTE] Full-Duplex is always used when devices are operating at 1000Mbps/1Gpbs and/or Fiber-Optic 1000BASE-SX