Hardware Reference
In-Depth Information
Fast Ethernet
Fast Ethernet requires adapters, hubs, switches, and UTP or fiber-optic cables designed to support its
rated speed. Some early Fast Ethernet products supported only 100Mbps, but eventually all Fast
Ethernet products were combination devices that ran at both 10Mbps and 100Mbps, enabling
backward compatibility with older 10Mbps Ethernet network hardware. Today, Fast Ethernet has
largely been replaced by Gigabit Ethernet in current network adapters and chipsets.
Note
Some specifications say that Fast Ethernet supports 200Mbps. This is because it normally runs
in full-duplex mode (sends/receives data simultaneously), which gives it an effective speed of
200Mbps with both directions combined. Still, the throughput in any one direction remains the
same (100Mbps). Full-duplex operation requires that all hardware in the connection, including
adapters and switches, be capable of running in full-duplex and be configured to run in full-
duplex (or automatically detect full-duplex signals).
Both the most common form of Fast Ethernet (100BASE-TX) and 10BASE-T standard Ethernet use
two of the four wire pairs found in UTP Category 5 cable. (These wire pairs are also found in CAT
5e, CAT 6, and CAT 6a cable.) An alternative Fast Ethernet standard called 100BASE-T4 uses all
four wire pairs in UTP Category 5 cable, but this Fast Ethernet standard was never popular and is
seldom seen today.
Gigabit Ethernet
Gigabit Ethernet also requires special adapters, hubs, switches, and cables. When Gigabit Ethernet
was introduced, most installations used fiber-optic cables, but today, CAT 5e/6/6a is recommended
(and those cable grades are also compatible with Fast Ethernet). Gigabit Ethernet for UTP is also
referred to as 1000BASE-T.
Unlike Fast Ethernet and standard Ethernet over UTP, Gigabit Ethernet uses all four wire pairs. Thus,
Gigabit Ethernet requires dedicated Ethernet cabling; you can't “borrow” two wire pairs for
telephone or other data signaling with Gigabit Ethernet as you can with the slower versions. Almost
all Gigabit Ethernet adapters can also handle 10BASE-T and 100BASE-TX Fast Ethernet traffic,
enabling you to interconnect all three UTP-based forms of Ethernet on a single network.
Gigabit Ethernet hardware was initially very expensive, thus limiting the use of Gigabit Ethernet to
high-end network interconnections. More recently, the prices of cables, adapters, and especially
switches has fallen dramatically, making Gigabit the recommended choice for all new cable, adapter,
and switch installations. Most integrated Ethernet adapters in recent systems also support Gigabit
Ethernet.
Neither Fast Ethernet nor Gigabit Ethernet supports the use of thin or thick coaxial cable originally
used with traditional Ethernet, although you can interconnect coaxial cable-based and UTP-based
Ethernet networks by using media converters or specially designed hubs and switches.
10 Gigabit Ethernet
10 Gigabit Ethernet is a high-speed networking standard that incorporates many different types of
physical interconnections including several that are fiber optic and copper based. Of all of the
 
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