The duplex command is used to set the duplex mode of a switch port, which can be either half-duplex or full-duplex. Note: The Catalyst switches/modules, such as the Catalyst 6500/6000, 4500/4000, 3550, and 2950, support 10/100/1000 Mbps negotiated Ethernet interfaces or ports. These ports work on 10 Mbps, 100 Mbps, or 1000 Mbps speed based on their connection to the other end. These 10/100/1000 Mbps ports can be. In Figure 1, port F0/1 on switch S1 and S2 are manually configured with the full keyword for the duplex command, and the 100 keyword for the speed command. Also negotiates flow control (enabled or disabled). The ordinary TX port does not support speed 1000.