Lecture

Week 13 Lesson Plan Addendum

Networking

Cabling Color Codes and Pinouts



A typical network configuration is shown below. The cabling, color codes and assorted pinouts are included without much discussion.



Cabling Cisco Devices


Unshielded Twisted Pair (UTP) Cable

Twisted pair cabling comes in two varieties: shielded and unshielded. Unshielded twisted pair (UTP) is the most popular and is generally the best option for school networks (See fig. 1).

[twisted pair cabling image]
Fig.1. Unshielded twisted pair

The quality of UTP may vary from telephone-grade wire to extremely high-speed cable. The cable has four pairs of wires inside the jacket. Each pair is twisted with a different number of twists per inch to help eliminate interference from adjacent pairs and other electrical devices. The EIA/TIA (Electronic Industry Association/Telecommunication Industry Association) has established standards of UTP and rated five categories of wire.

Categories of Unshielded Twisted Pair

Type

Use

Category 1

Voice Only (Telephone Wire)

Category 2

Data to 4 Mbps (LocalTalk)

Category 3

Data to 10 Mbps (Ethernet)

Category 4

Data to 20 Mbps (16 Mbps Token Ring)

Category 5

Data to 100 Mbps (Fast Ethernet)

One difference between the different categories of UTP is the tightness of the twisting of the copper pairs. The tighter the twisting, the higher the supported transmission rate and the greater the cost per foot. Buy the best cable you can afford; most schools purchase Category 3 or Category 5. Category 5 cable is highly recommended.

If you are designing a 10 Mbps Ethernet network and are considering the cost savings of buying Category 3 wire instead of Category 5, remember that the Category 5 cable will provide more "room to grow" as transmission technologies increase. Both category 3 and category 5 UTP have a maximum segment length of 100 meters. In Florida, Category 5 cable is required for retrofit grants. 10BaseT refers to the specifications for unshielded twisted pair cable (category 3, 4, or 5) carrying Ethernet signals.

Unshielded Twisted Pair Connector

The standard connector for unshielded twisted pair cabling is an RJ-45 connector. This is a plastic connector that looks like a large telephone-style connector (See fig. 2). A slot allows the RJ-45 to be inserted only one way. RJ stands for Registered Jack, implying that the connector follows a standard borrowed from the telephone industry. This standard designates which wire goes with each pin inside the connector.

[RJ-45 connector image]
Fig.2. RJ-45 connector





Standard UTP color codes and pinouts

T568A





T568A pin assignment scheme

Pin #

Conductor Color Code



1

white/green



2

green



3

white/orange



4

blue



5

white/blue



6

orange



7

white/brown



8

brown


T568B




T568B pin assignment scheme

Pin #

Conductor Color Code



1

white/orange



2

orange



3

white/green



4

blue



5

white/blue



6

green



7

white/brown



8

brown









Click here to go back to the list of pinouts






100BASE-TX / 10BASE-T CROSSOVER

back to the list of pin layout






100BASE-TX / 10BASE-T CROSSOVER











Plug A



Plug B



Pin #

Signal

Conductor Color Code

Pin #

Signal

Conductor Color Code

1

Tx+

white/green

1

Tx+

white/orange

2

Tx-

green

2

Tx-

orange

3

Rx+

white/orange

3

Rx+

white/green

4

N/U

blue

4

N/U

blue

5

N/U

white/blue

5

N/U

white/blue

6

Rx-

orange

6

Rx-

green

7

N/U

white/brown

7

N/U

white/brown

8

N/U

brown

8

N/U

brown

Legend: N/U - Not used. May be either short or open circuit










Shielded Twisted Pair (STP) Cable

A disadvantage of UTP is that it may be susceptible to radio and electrical frequency interference. Shielded twisted pair (STP) is suitable for environments with electrical interference; however, the extra shielding can make the cables quite bulky. Shielded twisted pair is often used on networks using Token Ring topology.


Coaxial Cable

Coaxial cabling has a single copper conductor at its center. A plastic layer provides insulation between the center conductor and a braided metal shield (See fig. 3). The metal shield helps to block any outside interference from fluorescent lights, motors, and other computers.


[coaxial cabling image]
Fig.3. Coaxial cable

Although coaxial cabling is difficult to install, it is highly resistant to signal interference. In addition, it can support greater cable lengths between network devices than twisted pair cable. The two types of coaxial cabling are: thick coaxial and thin coaxial.

Thin coaxial cable is also referred to as thinnet. 10Base2 refers to the specifications for thin coaxial cable carrying Ethernet signals. The 2 refers to the approximate maximum segment length being 200 meters. In actual fact the maximum segment length is 185 meters. Thin coaxial cable is popular in school networks, especially linear bus networks.

Thick coaxial cable is also referred to as thicknet. 10Base5 refers to the specifications for thick coaxial cable carrying Ethernet signals. The 5 refers to the maximum segment length being 500 meters. Thick coaxial cable has an extra protective plastic cover that helps keep moisture away from the center conductor. This makes thick coaxial a great choice when running longer lengths in a linear bus network. One disadvantage of thick coaxial is that it does not bend easily and is difficult to install.

Coaxial Cable Connectors

The most common type of connector used with coaxial cables is the Bayone-Neill-Concelman (BNC) connector (See fig. 4). Different types of adapters are available for BNC connectors, including a T-connector, barrel connector, and terminator. Connectors on the cable are the weakest points in any network. To help avoid problems with your network, always use the BNC connectors that crimp, rather than screw, onto the cable.

[BNC connector image]
Fig.4. BNC connector

Fiber Optic Cable

Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials (See fig. 5). It transmits light rather than electronic signals, eliminating the problem of electrical interference. This makes it ideal for certain environments that contain a large amount of electrical interference. It has also made it the standard for connecting networks between buildings, due to its immunity to the effects of moisture and lighting.

Fiber optic cable has the ability to transmit signals over much longer distances than coaxial and twisted pair. It also has the capability to carry information at vastly greater speeds. This capacity broadens communication possibilities to include services such as video conferencing and interactive services. The cost of fiber optic cabling is comparable to copper cabling; however, it is more difficult to install and modify. 10BaseF refers to the specifications for fiber optic cable carrying Ethernet signals.

[fiber optic cabling image]
Fig.5. Fiber optic cable

Facts about fiber optic cables:

  • Outer insulating jacket is made of Teflon or PVC.

  • Kevlar fiber helps to strengthen the cable and prevent breakage.

  • A plastic coating is used to cushion the fiber center.

  • Center (core) is made of glass or plastic fibers.

Fiber Optic Connector

The most common connector used with fiber optic cable is an ST connector. It is barrel shaped, similar to a BNC connector. A newer connector, the SC, is becoming more popular. It has a squared face and is easier to connect in a confined space.


















Please note that there are several competing pinouts for this kind of connection. For example, Cisco console adapter has different pin layout even though it is also a DB9-to-8-pin connector device.

EIA/TIA-561 Pin Layout Diagram with DB9 connector

EIA/TIA-561 pin layout (serial interface via 8-pin connector)

EIA/TIA-561 Pin Layout Diagram with DB25 connector

EIA/TIA-561 DB25 pin layout (serial interface via 8-pin connector)
 

The EIA/TIA-561 standard itself only applies to the 8P8C end of such cable.


DB25 serial port available.


EIA/TIA-561 Pin Layout and RS-232 pin assignments








8P8C (RJ45)

DB9

DB25

Signal

Description

1

9

22

RI

Ring Indicator

2

1

8

DCD

Data Carrier Detect

3

4

20

DTR

Data Terminal Ready

4

5

7

SG

Signal Ground

5

2

3

RXD

Received Data

6

3

2

TXD

Transmitted Data

7

8

5

CTS

Clear To Send

8

7

4

RTS

Request To Send





Additional assorted Pinouts


25 pin loopback


2-3

3-2

4-5

5-4

6-20

7-7

20-6


Keyboard pinout


PS/2 DIN


Data 1 2

N/U 2 3

GND 3 4

5v 4 5

CLK 5 1

N/U 6 -


RJ 45 Western Electric


1-1 White/Blue

2-2 Blue

3-3 White/orange

4-4 Orange

5-5 White/green

6-6 Green

7-7 White/brown

8-8 Brown






RJ45 Crossover cable


1-3

2-6

3-1

4-4

5-5

6-2

7-7

8-8


RJ45 Loop back (or rollover cable)


RJ45 RJ45 DB9 Signal

1 8 8 CTR

2 7 6 DSR

3 6 2 RXD

4 5 5 GND

5 4 5 GND

6 3 3 TXD

7 2 4 DTR

8 1 7 RTS