BITS1313 Data Communication and
Networks
LAB 3
UTP CABLE CONSTRUCTION AND TESTING
By the end of this section of the practical, the student should be able to:
i. Build a Category 5 UTP straight through, rollover and crossover cable
ii. Test the cable for continuity and correct pin-outs, the correct colour of wire
on the right pin.
iii. Use a simple cable tester to verify whether a straight-through or
crossover cable is good or bad.
1.1 Introduction
Coaxial cable, unshielded twisted pair (UTP) and shielded twisted pair (STP)
are types of copper cables that can be used in a network to provide different
capabilities. Twisted-pair cable can be configured for straight through,
crossover, or rollover signaling. These terms refer to the individual wire
connections, or pin-outs, from one end to the other end of the cable. A
straight-through cable is used to connect unlike devices such as a switch and
a computer. A crossover cable is used to connect similar devices such as two
switches or two computers. A rollover cable is used to connect a computer to
the console port of a router. Different pin-outs are required because the
transmit and receive pins are in different locations on each of these devices.
1.2 Straight-Through Cable Construction
The cable constructed will be a four-pair, eight-wire, straight-through cable,
which means that the color of wire on Pin 1 on one end of the cable will be
the same as that of Pin 1 on the other end. Pin 2 will be the same as Pin 2,
and so on. The cable will be wired to TIA/EIA T568B at both end, which
determines what color wire is on each pin. T568B also called AT&T
specification.
1.3 Preparation
The following resources will be required: Please work in groups of TWO
members.
i. 1 x 1 m length of Category 5/5e/6 cabling per team
ii. x RJ-45 connectors
iii. RJ-45 crimping tools
iv. Ethernet cabling continuity tester which can test straight-through or
crossover type cables, T568A or T568B
v. Wire cutters
Table 3.1 shows the sequence of wire color for T568B standard.
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Table 3.1: Cabling Pin-Out Information for T568B
Pin no. Pair no. Function Wire Color
1 2 Transmit White/ Orange
2 2 Transmit Orange
3 3 Receive White/ Green
4 1 Not used Blue
5 1 Not used White/ Blue
6 3 Receive Green
7 4 Not used White/ Brown
8 4 Not used Brown
Figure 3.1 shows the technique to insert the UTP cable into the RJ45
connector.
Figure 3.1 : Wiring standard -UTP cable T568B and RJ45
connector
Step By Step - Crimping UTP Cable
1. Take a 1 meter length of Category 5 cable.
2. Strip ~5 cm of jacket off of one end of the cable.
3. Hold the four pairs of twisted cables tightly where jacket was cut away.
Reorganize the cable pairs into the order of the T568B as shown in Figure 3.1
wiring standard.
4. Hold the jacket and cable in one hand.
5. Untwist and order the wire pairs according to the color scheme.
6. Flatten, straighten, and line up the wires. Trim them in a straight line to within
~1.5 cm from the edge of the jacket. Be sure not to let go of the jacket and
the wires, which are now in the proper order.
7. Place an RJ-45 plug on the end of the cable, with the prong on the underside
and the orange pair to the left side of the connector.
8. Gently push the plug onto wires until the copper ends of the wires can be
seen through the end of the plug. Make sure the end of the jacket is inside
the plug.
9. If everything is correct, crimp the plug hard enough to force the contacts
through the insulation on the wires, completing the conducting path.
10.Repeat the steps to terminate the other end of the cable.
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1.4 Crossover Cable Construction
The cable will be wired to TIA/EIA T568B at one end hence the other end will be
TIA/EIA T568A, which determines what color wire is on each pin T568B and
T568A. A crossover cable can be used as a backbone cable to connect two or
more hubs or switches in a LAN, or to connect two isolated workstations to
create a mini-LAN. This will allow the connection of two workstations or a server
and a workstation without the need for a hub between them. This can be very
helpful for training and testing. To connect more than two workstations, a hub or
a switch will be needed.
Table 3.2: Cabling Pin-Out Information for T568A
Pin no. Pair no. Function Wire Color
1 2 Transmit White/ Green
2 2 Transmit Green
3 3 Receive White/ Orange
4 1 Not used Blue
5 1 Not used White/ Blue
6 3 Receive Orange
7 4 Not used White/ Brown
8 4 Not used Brown
Figure 3.2: Wiring standard -UTP cable T568A
To construct the cross over cable, follow the 3.2.2 step by step procedure. For
the color sequence, one end must follow T568B color standard and the other
end follow T568A color standard.
1.5 Basic Cable Testing
There are a number of basic cable testers available. They usually consist of one
or two small boxes with RJ-45 jacks. Plug the cables to be tested the RJ-45 jacks.
Many models are designed to test only Ethernet UTP cable. Both ends of the
cable are plugged in to the proper jacks. The tester will test all eight wires and
indicate whether the cable is good or bad. Simple testers may have only a
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Networks
single light to indicate the cable is good or bad. Other testers may have eight
lights to indicate which wire is bad. The testers have internal batteries to do
continuity checks on the wires. Refer to the instructions from the
manufacturer.
Step by Step – Test UTP Cable
1. Insert one ends of the cable into the cable tester and the other end
into the split cable tester.
2. Turn on the switch.
3. Observe the results.
Table 3.2 : Testing Result For UTP Cable Testing
LED color Description Action
All four LED blink
with Perfect. All connection is success Passed
green color
Some is green The red color shows the pair is
some is incorrect Failed. Do it again
red
Some LED did not The LED that’s not blink means the
blink wire is Failed. Do it again
short or the crimping is not very
well.
Based on Table 3.2, if all four LEDs blink with green color means the
connection is perfect. The cable can be used now. Otherwise, it is failed and
follows the procedure 3.3 again.
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BITS1313 Data Communication and
Networks
1.6 Self-Review Questions
1. Identify the types of cables used for the following connections for data
communication:
Device Types of standard cable
connection connection
Computer to switch crossover
Switch to switch crossover
Router to switch straight through
Hub to hub straight thrugh
Computer to Router crossover
2. List down the correct sequence color for wiring cables according to:
T568B
T568A standard standard
1.
white/orang
1.white/green e
2.green 2. orange
3. white
3.white/orange green
4.blue 4. blue
5.
5.white/blue white/blue
6.orange 6. green
7. white
7.white/brown /brown
8.brown 8.brown
3. Describe the main difference between a straight through cable, a
crossover cable and a rollover cable based on its wiring and usage.
4. Let say you didn’t follow the color standard for T568A or T568B and
create your own sequence color for both end. You perform the crimping
technique perfectly for both ends using your own sequence color. Do
you think the cable is working? Why?
