Interface Speed and Duplex Issues

Many UTP-based Ethernet interfaces support multiple speeds, either full- or half-duplex, and support IEEE standard autonegotiation (as discussed in Chapter 6’s section “Autonegotiation”). These same interfaces can also be configured to use a specific speed using the speed {10 | 100 | 1000} interface subcommand, and a specific duplex using the duplex {half | full} interface subcommand. With both configured, a switch or router disables the IEEE-standard autonegotiation process on that interface.

The show interfaces and show interfaces status commands list both the actual speed and duplex settings on an interface, as demonstrated in Example 10-3.

Example 10-3 Displaying Speed and Duplex Settings on Switch Interfaces ...

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