Lab Worksheet 1
Building an Ethernet Cable
(Ref. CCNA5 Introduction to Network 4.2.2.7)
Objective:
 Analyze Ethernet Cabling
Standards and Pinouts
 Construct a Category 5e (CAT5e)
Unshielded Twisted Pair (UTP)
Ethernet Straight-through or
Crossover cable.
1. TIA-EIA T568A and TIA-EIA T568B Industrial Standards
The Telecommunications Industry Association/Electronic Industries
Association (TIA/EIA) has specified unshielded twisted pair (UTP) cabling
standards for use in LAN cabling environments. TIA/EIA 568-A and 568-B are
the standards most commonly used in LAN cabling for organizations and they
determine which color wire is used on each pin. T568B, also called AT&T
specification, is more common in the US.
The following table shows the Wiring Pin-out information for TIA/EIA568A
(T568A) and TIA/EIA568B (T568B).
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1
2
3
4
5
6
7
1
8
2
3
4
5
6
7
8
T568B
T568A
A CAT5e cable will be wired to either TIA/EIA T568B or T568A standards on
each end. There are 2 types of CAT5e cables, which are called
straight-through cable and crossover cable. The difference between
straight-through and crossover cable is as follow:
Cable Type
Connector at one end
Connector at the other end
Straight-through
T568B
T568B
Crossover
T568A
T568B
2. Straight-through or Crossover?
Use of straight-through cable
PC to Switch
PC to Hub
Switch to Router
Hub to Router
Use of crossover cable
PC to PC
Switch to Switch
Hub to Hub
Switch to Hub
PC to Router
2

Using a crossover or straight-through cable incorrectly between devices
may not damage the devices, but connectivity and communication
between the devices will not take place.

This is a common error in the lab and checking that the device
connections are correct should be the first troubleshooting action if
connectivity is not achieved
3. How to make your own cable?
Step 1
1.1 Find a group mate
1.2 Each group will be given:

a cable

Two RJ45 connectors

a cable crimping tool

Ethernet cable tester
1.3 Determine the cable type to be made (straight-through or crossover)
Step 2
2.1 At one end of the cable, strip off around 5cm of the outer jacket carefully.
Note: do not break the wires or damage the insulation of the wires.
2.2 Untwist all wire pairs.
2.3 Flatten and straighten each wire.
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Step 3
3.1 Reorganize the wires in the order of T568B (or T568A) wiring standard.
3.2 Line up the wires closely. Check again to make sure the color sequence
follows desired standard.
3.3 Trim the wires in a straight line to around 1.5cm, which can fit into an
RJ-45 connector.
Note: do not trim away too much, otherwise the wires would be too short
to reach the end of the connector; do not leave too long as well,
because the untwisted section near the connector is a primary source of
electrical noise.
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Step 4
4.1 Hold an RJ-45 connector with the copper contacts facing up, so that
from left to right, it is Pin 1 to 8.
4.2 Firmly insert the wires into the connector.
Note: make sure the wires are still in the proper color sequence, and
each wire goes into the corresponding pin.
4.3 It is the best if the outer jacket also goes inside the connector. This
provides stress relief and protects the wires from damage or disorder.
4.4 Push the wires into the connector until they reach the top of the
connector. If so, they can be seen through the top of the connector.
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Step 5
5.1 Insert the RJ-45 connector with cable into the crimper.
Note: push the wires deep into the connector again to make sure they
can still reach the end of the connector.
5.2 Crimp the plug hard enough to force the copper contacts cutting through
the insulation of the wires, so that conducting path for electricity is
completed.
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Step 6
Repeat step 2 through step 5 on the other end of the cable. Think twice
which standard (T568A or T568B) you should follow to make a desired
cable type.
Step 7
Try to list some reasons for failure that could be possibly told by
checking the cable with eyes.
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Step 8
Test the cable by using a cable tester (Lab worksheet 2).
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