Chapter Description

Familiarize yourself v some familiar network cables and also take a closer look in ~ common varieties of network media, including twisted-pair cable, coaxial cable, fiber-optic cable, and also wireless.

From the Book


CCNA Self-Study: CCNA Basics (CCNAB)


Network Media Types

Upon perfect this chapter, you will be may be to:

Describe the primary species and offers of twisted-pair cables

Describe the primary species and supplies of coaxial cables

Describe the primary types and offers of fiber-optic cables

Describe the primary species and provides of wireless media

Compare and also contrast the primary types and offers of various media

Network media is the actual course over i beg your pardon an electric signaltravels as it move from one ingredient to another. This chapter describes thecommon types of network media, including twisted-pair cable, coaxial cable,fiber-optic cable, and also wireless.

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Twisted-Pair Cable

Twisted-pair cable is a form of cabling that is used for telephonecommunications and most contemporary Ethernet networks. A pair that wires develops acircuit that deserve to transmit data. The pairs room twisted to provide protectionagainst crosstalk, the noise produced by adjacent pairs. When electricalcurrent flows v a wire, it create a small, circular magnetic ar aroundthe wire. Once two wires in an electrical circuit are put close together,their magnetic areas are the precise opposite of every other. Thus, the twomagnetic fields cancel each other out. They also cancel out any outside magneticfields. Twisting the wires deserve to enhance this cancellation effect. Usingcancellation in addition to twisting the wires, cable developers can effectivelyprovide self-shielding for cable pairs within the network media.

Two an easy types of twisted-pair cable exist: unshielded twisted pair (UTP)and shielded twisted pair (STP). The following sections comment on UTP and also STPcable in an ext detail.

UTP Cable

UTP cable is a tool that is composed of bag of wires (see figure 8-1). UTP cable is used in a variety of networks. Each of the eight separation, personal, instance copper wires in UTP cable is spanned by one insulating material. In addition, the wires in each pair are twisted roughly each other.

figure 8-1 Unshielded Twisted-Pair Cable

UTP cable relies exclusively on the cancellation effect developed by the twistedwire pairs to border signal deterioration caused through electromagnetic interference(EMI) and radio frequency interference (RFI). To additional reduce crosstalkbetween the bag in UTP cable, the variety of twists in the cable pairs varies.UTP cable need to follow an exact specifications governing how plenty of twists or braidsare permitted per meter (3.28 feet) the cable.

UTP cable regularly is installed using a Registered Jack 45 (RJ-45) connector (see figure 8-2). The RJ-45 is one eight-wire connector used frequently to connect computers onto a local-area network (LAN), specifically Ethernets.

number 8-2 RJ-45 Connectors

When offered as a networking medium, UTP cable has 4 pairs of either 22- or24-gauge copper wire. UTP offered as a networking medium has actually an impedance of 100ohms; this differentiates that from other species of twisted-pair wiring together asthat supplied for call wiring, which has actually impedance of 600 ohms.

UTP cable offers countless advantages. Because UTP has an external diameter ofapproximately 0.43 cm (0.17 inches), its tiny size have the right to be advantageous duringinstallation. Since it has actually such a little external diameter, UTP does not fillup wiring ducts as swiftly as other species of cable. This can be an extremelyimportant factor to consider, an especially when installing a network in an olderbuilding. UTP cable is simple to install and is much less expensive than other varieties ofnetworking media. In fact, UTP prices less every meter than any kind of other kind of LANcabling. And also because UTP deserve to be offered with many of the major networkingarchitectures, it continues to grow in popularity.

Disadvantages additionally are associated in using twisted-pair cabling, however. UTPcable is much more prone to electric noise and also interference than other varieties ofnetworking media, and also the distance between signal boosts is shorter for UTP thanit is for coaxial and fiber-optic cables.

Although UTP to be once considered to be slower at transmitting data than othertypes that cable, this is no much longer true. In fact, UTP is considered the fastestcopper-based medium today. The complying with summarizes the functions of UTPcable:

Speed and throughput—10 come 1000 Mbps

Average cost per node—Least expensive

Media and connector size—Small

Maximum cable length—100 m (short)

Commonly used species of UTP cabling room as follows:

Category 1—Used because that telephone communications. No suitablefor transmitting data.

Category 2—Capable the transmitting data at increases to 4megabits per 2nd (Mbps).

Category 3—Used in 10BASE-T networks. Have the right to transmit data atspeeds approximately 10 Mbps.

Category 4—Used in Token Ring networks. Have the right to transmit data atspeeds as much as 16 Mbps.

Category 5—Can transmit data at increases to 100Mbps.

Category 5e —Used in networks running at accelerates to 1000Mbps (1 gigabit per 2nd ).

Category 6—Typically, category 6 cable consists of four pairsof 24 American wire Gauge (AWG) copper wires. Group 6 cable is currently thefastest traditional for UTP.

Shielded Twisted-Pair Cable

Shielded twisted-pair (STP) cable combine the approaches of shielding, cancellation, and also wire twisting. Every pair of wires is sheathe in a metallic silver paper (see figure 8-3). The 4 pairs the wires then space wrapped in an in its entirety metallic braid or foil, commonly 150-ohm cable. As stated for usage in Ethernet network installations, STP reduces electric noise both in ~ the cable (pair-to-pair coupling, or crosstalk) and also from exterior the cable (EMI and RFI). STP normally is installed with STP data connector, i beg your pardon is created especially for the STP cable. However, STP cabling likewise can usage the exact same RJ connectors the UTP uses.

figure 8-3 Shielded Twisted-Pair Cable

Although STP stays clear of interference better than UTP, the is an ext expensive anddifficult come install. In addition, the metallic shielding must be base atboth ends. If that is improperly grounded, the shield acts prefer an antenna andpicks up unwanted signals. Since of its expense and challenge with termination,STP is rarely used in Ethernet networks. STP is generally used in Europe.

The following summarizes the features of STP cable:

Speed and throughput—10 come 100 Mbps

Average cost per node—Moderately expensive

Media and connector size—Medium to large

Maximum cable length—100 m (short)

When comparing UTP and STP, save the following points in mind:

The speed of both types of cable is usually satisfactory because that local-areadistances.

These are the least-expensive media for data communication. UTP is lessexpensive 보다 STP.

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Because most buildings are already wired with UTP, plenty of transmissionstandards are adjusted to usage it, to prevent costly rewiring through an alternativecable type.