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CompTIA A+ Certification All-in-One Exam Guide

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communicate just fine.

Most modern Ethernet networks employ one of three speeds: 10BaseT,

100BaseT, or 1000BaseT. As the numbers in the names suggest, 10BaseT

networks run at 10 Mbps, 100BaseT networks (called Fast Ethernet) run at

100 Mbps, and 1000BaseT networks (called Gigabit Ethernet) run at 1000

Mbps, or 1 Gbps. All three technologies—sometimes referred to collectively

as 10/100/1000BaseT or just plain Ethernet—use a star bus topology

(discussed in the next section) and connect via a type of cable called

unshielded twisted pair (UTP).

NOTE Ethernet developers continue to refine the technology. Fast

Ethernet (100BaseT) is still out there on many older devices. Gigabit

Ethernet (1000BaseT) might be the most common desktop standard now, but

10-Gigabit Ethernet is common on server-to-server connections. 40/100-

Gigabit Ethernet is slowly encroaching as well.

The Ethernet Star Bus

With all Ethernet networks, every individual host connects to a central box.

You attach each system to this box via cables to special ports. The box takes

care of all the tedious details required by the network to get frames sent to the

correct systems. This layout (or topology), which looks something like a star,

is called a star bus topology (see Figure 18-8). (The bus refers to the internal

wiring in the box. The star refers to the wires leading from the box to the

hosts. Star bus is thus a hybrid topology.)

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