Hardware Reference
In-Depth Information
DB-15 (for Thicknet coaxial cables). Some older 10Mbps adapters have a combination of two or all
three of these connector types; adapters with two or more connectors are referred to as
combo
adapters
. Token-Ring adapters can have a 9-pin connector called a DB-9 (for Type 1 STP cable) or
sometimes an 8P8C (RJ-45) jack (for Type 3 UTP cable).
Figure 17.4
shows all three of the Ethernet
connectors.
Figure 17.4. Three Ethernet connectors on two NICs: Modern 8P8C (RJ-45) connector (top
center), Obsolete DB-15 connector (bottom right), and Obsolete BNC connector (bottom left).
Note
Although RJ-45 is the common name for the UTP Ethernet connector, this is a misnomer. The
correct name for the connector is 8P8C, which indicates an 8-pin, 8-conductor connector. The
actual RJ-45S connector is an eight-position connector but is used for telephone rather than
computer data. An RJ-45S jack has a slightly different shape than the connector used for
Ethernet, and it includes a cutout on one side to prevent unkeyed connectors from being
inserted into it.
For drawings of the true RJ-45S jack and other telephone jacks, see
Ethernet NICs made for client-PC use on the market today are designed to support unshielded
twisted-pair (UTP) cable exclusively. Cards using BNC or DB-15 connectors would be considered
obsolete.
For maximum economy, NICs and network cables must match, although media converters can
interconnect networks based on the same standard, but using different cable.
Network Cables for Wired Ethernet
Originally, all networks used some type of cable to connect the computers on the network to each
other. Although various types of wireless networks are now on the market, many office and home
