bài giảng mạng máy tính căn bản chương 5 hệ thống cáp của lan và wancabling lan and wan

Phan Vĩnh Thuần Computer Network 1
Chương 5
HỆ THỐNG CÁP CỦA LAN VÀ WAN
CABLING LAN AND WAN
Overview
•
Even though each local-area network is
unique, there are many design aspects that
are common to all LANs. For example, most
LANs follow the same standards and the
same components. This module presents
information on elements of Ethernet LANs
and common LAN devices.
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•
There are several wide-area network (WAN)
connections available today. They range
from dial-up to broadband access, and differ
in bandwidth, cost, and required equipment.
This module presents information on the
various types of WAN connections.
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•
Students completing this module should be
able to:
–
Identify characteristics of Ethernet
networks.
–
Identify straight-through, crossover, and
rollover cables.

–
Describe the function, advantages, and
disadvantages of repeaters, hubs,
bridges, switches, and wireless network
components.
–
Describe the function of peer-to-peer
networks.
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–
Describe the function, advantages, and
disadvantages of client-server networks.
–
Describe and differentiate between serial,
Integrated Services Digital Network
(ISDN), digital subscriber line (DSL), and
cable modem WAN connections.
–
Identify router serial ports, cables, and
connectors.
–
Identify and describe the placement of
equipment used in various WAN
configurations.
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5.1. Cabling the LAN
5.1.1. LAN physical layer
•
Various symbols are used to represent
media types. Token Ring is represented by

a circle. Fiber Distributed Data Interface
(FDDI) is represented by two concentric
circles and the Ethernet symbol is
represented by a straight line. Serial
connections are represented by a lightning
bolt.
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•
Each computer network can be built with
many different media types. The function of
media is to carry a flow of information
through a LAN. Wireless LANs use the
atmosphere, or space, as the medium. Other
networking media confine network signals to
a wire, cable, or fiber. Networking media are
considered Layer 1, or physical layer,
components of LANs.
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•
Each media has advantages and
disadvantages. Some of the advantage or
disadvantage comparisons concern:
–
Cable length
–
Cost
–
Ease of installation
–

Susceptibility to interference
•
Coaxial cable, optical fiber, and even free
space can carry network signals. However,
the principal medium that will be studied is
Category 5 unshielded twisted-pair cable
(Cat 5 UTP) which includes the Cat 5e
family of cables.
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•
Many topologies support LANs, as well as
many different physical media. The figure
shows a subset of physical layer
implementations that can be deployed to
support Ethernet.
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5.1.2. Ethenet trong khuôn viên trường
học (Ethernet in the campus)
•
Ethernet is the most widely used LAN
technology. Ethernet was first implemented
by the Digital, Intel, and Xerox group,
referred to as DIX. DIX created and
implemented the first Ethernet LAN
specification, which was used as the basis
for the Institute of Electrical and Electronics
Engineers (IEEE) 802.3 specification,
released in 1980.
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•
Later, the IEEE extended 802.3 to three
new committees known as 802.3u (Fast
Ethernet), 802.3z (Gigabit Ethernet over
Fiber), and 802.3ab (Gigabit Ethernet over
UTP).
•
Network requirements might dictate that
an upgrade to one of the faster Ethernet
topologies be used. Most Ethernet
networks support speeds of 10 Mbps
and 100 Mbps.
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•
The new generation of multimedia,
imaging, and database products, can easily
overwhelm a network running at traditional
Ethernet speeds of 10 and 100 Mbps.
Network administrators may consider
providing Gigabit Ethernet from the
backbone to the end user. Costs for
installing new cabling and adapters can
make this prohibitive. Gigabit Ethernet to
the desktop is not a standard installation at
this time.
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•
In general, Ethernet technologies can be
used in a campus network in several
different ways:

–
An Ethernet speed of 10 Mbps can be
used at the user level to provide good
performance. Clients or servers that
require more bandwidth can use 100-
Mbps Ethernet.
–
Fast Ethernet is used as the link between
user and network devices. It can support
the combination of all traffic from each
Ethernet segment.
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–
To enhance client-server performance
across the campus network and avoid
bottlenecks, Fast Ethernet can be used
to connect enterprise servers.
–
Fast Ethernet or Gigabit Ethernet, as
affordable, should be implemented
between backbone devices
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5.1.3. Nhu cầu đường truyền Ethenet và bộ
nối (Ethernet media and connector
requirements)
•
Before selecting an Ethernet
implementation, consider the media and
connector requirements for each

implementation. Also, consider the level of
performance needed by the network.
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•
The cables and connector specifications
used to support Ethernet implementations
are derived from the Electronic Industries
Association and the Telecommunications
Industry Association (EIA/TIA) standards
body. The categories of cabling defined for
Ethernet are derived from the EIA/TIA-568
(SP-2840) Commercial Building
Telecommunications Wiring Standards.
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•
The figure compares the cable and
connector specifications for the most
popular Ethernet implementations. It is
important to note the difference in the media
used for 10-Mbps Ethernet versus 100-
Mbps Ethernet. Networks with a
combination of 10- and 100-Mbps traffic use
UTP Category 5 to support Fast Ethernet.
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5.1.4. Môi trường kết nối (Connection
media)
•
The figure illustrates the different
connection types used by each physical

layer implementation. The registered jack
(RJ-45) connector and jack are the most
common. RJ-45 connectors are discussed
in more detail in the next section.
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•
In some cases the type of connector on a
network interface card (NIC) does not match
the media that it needs to connect to. As shown
in Figure, an interface may exist for the 15-pin
attachment unit interface (AUI) connector. The
AUI connector allows different media to connect
when used with the appropriate transceiver. A
transceiver is an adapter that converts one type
of connection to another. Typically, a
transceiver converts an AUI to RJ-45, coax, or
fiber optic connector. On 10BASE5 Ethernet, or
Thicknet, a short cable is used to connect the
AUI with a transceiver on the main cable.
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5.1.5. Thực hiện UTP (UTP implementation)
•
EIA/TIA specifies an RJ-45 connector for UTP
cable. The letters RJ stand for registered jack, and
the number 45 refers to a specific wiring
sequence. The RJ-45 transparent end connector
shows eight colored wires. Four of the wires carry
the voltage and are considered “tip” (T1 through
T4). The other four wires are grounded and are

called “ring” (R1 through R4). Tip and ring are
terms that originated in the early days of the
telephone. Today, these terms refer to the positive
and the negative wire in a pair. The wires in the
first pair in a cable or a connector are designated
as T1 and R1. The second pair is T2 and R2, and
so on.
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•
The RJ-45 connector is the male component,
crimped on the end of the cable. When
looking at the male connector from the front,
the pin locations are numbered 8 on the left
down to 1 on the right as seen in Figure.