Data Cabling

Data Cabling

This section talks about the cabling used in today's networks. There's a lot of different type of cabling in today's networks and I am not going to cover all of them, but I will be talking about the most common cables used , which include UTP CAT5 straight through and crossover, Coax and a few more.

Cabling is very important if we want a network to work properly with minimum problems and bandwidth losses. There are certain rules which must never be broken when you're trying to design networks; otherwise you'll have problems when computers try to communicate.

In the near future, cabling will probably be something old and outdated since wireless communication seems to be gaining more ground, day by day. With that in mind, around 95% of companies still rely on cables.

Network Topology

The network’s topology refers to the physical layout of the nodes and hubs that make up the network. Choosing the right topology is important because the topology affects the type of networking equipment, cabling, growth path, and network management.

Today’s networking architectures fall into one of three categories:

• Star
• Bus
• Ring

Star Topology

All computers are connected to a single, centrally located point. This central point is usually a hub. All cabling used in a star topology is run from the point where the network nodes are located back to a central location.

  

Star Topology with a Central Hub

Bus Topology

The bus topology is the simplest network topology. Also known as a linear bus, all computers are connected to a contiguous cable or a cable joined together to make it contiguous. Figure above illustrates a bus topology. Ethernet is a common example of a bus topology.

Each computer determines when the network is not busy and transmits data as needed. Computers in a bus topology listen only for transmissions from other computers; they do not repeat or forward the transmission on to other computers.

Bus Topology

Ring Topology

A ring topology requires that all computers be connected in a contiguous circle, as shown in Figure above the ring has no ends or hub. Each computer in the ring receives signals (data) from its neighbor, repeats the signal, and passes it along to the next node in the ring. Because the signal has to pass through each computer on the ring, a single node or cable failure can take the entire ring down.

Ring Topology

Type of Cables

Technically, when you begin the planning stages of a new cabling installation, you should not have to worry about the types of applications used. The whole point of structured cabling Standards such as ANSI/TIA/EIA-568-B and ISO/IEC 11801 is that they will support almost any networking or voice application in use today.

Still, it is a good idea to have an understanding of the networking application you are cabling for and how that can affect the use of the cabling system. Further, because cabling that’s related to data also connects to various types of network devices, it is a good idea to have an understanding of the networking hardware used in common installations.

UTP (Unshielded Twisted Pair)

Unshielded Twisted Pair (UTP) cable is most certainly by far the most popular cable around the world. UTP cable is used not only for networking but also for the traditional telephone (UTP-Cat 1). There are 6 different types of UTP categories and, depending on what you want to achieve, you would need the appropriate type of cable. UTP-CAT5 is the most popular UTP cable; it came to replace the good old coaxial cable which was not able to keep up with the constant growing need for faster and more reliable networks.

Category 1/2/3/4/5/6 – a specification for the type of copper wire (most telephone and network wire is copper) and jacks. The number (1, 3, 5, etc) refers to the revision of the specification and in practical terms refers to the number of twists inside the wire (or the quality of connection in a jack).

UTP Category	Speed	Example
Cat 1	1 Mbps	Traditional telephone & ISDN
Cat 2	4 Mbps	Token Ring
Cat 3	10 Mbps	Token Ring & 10BaseT
Cat 4	16 Mbps	Token Ring
Cat 5	100 Mbps	Ethernet (10Mbps) Fast Ethernet (100Mbps) Token Ring (16Mbps)
Cat 5e	1000 Mbps	Gigabit Ethernet
Cat 6	1000 Mbps	Gigabit Ethernet

6 different UTP Categories

UTP Cat 5

There are 2 popular wiring schemes that most people use today: the T-568A and T-568B, that differ only in which color coded pairs are connected - pair 2 and 3 are reversed. Both work equally well, as long as you don't mix them! If you always use only one version, you're OK, but if you mix A and B in a cable run, you will get crossed pairs!

UTP Cat 5 can be used in 3 different color codes depending on the situation:

1)    Straight Thru

2)    Cross Over

3)    Roll Over – to used with maintenance router only

T568A & T568B Color Code

Straight Thru

Cross Over

Roll Over

So, which cable do I need? The table below helps us determine which type of cable we need for the setup:

568-B Wiring Pair # Wire Pin # 1-White/Blue White/Blue 5 Blue/White 4 2-Wht./Orange White/Orange 1 Orange White 2 3-White/Green White/Green 3 Green/White 6 4-White/Brown White/Brown 7 Brown/White 8 < 568-B Diagram

 

568-A Wiring

Pair #	Wire	Pin #
1-White/Blue	White/Blue	5
	Blue/White	4
2-White/Green	White/Green	1
	Green/White	2
3-White/Orange	White/Orange	3
	Orange/White	6
4-White/Brown	White/Brown	7
	Brown/White	8
< 568-A Diagram

 

 

 

Patch Cable Assembly Instructions

 

1. Skin off the cable jacket approximately 1" or slightly more.
2. Un-twist each pair, and straighten each wire between the fingers.
3. Place the wires in the order of one of the two diagrams shown above (568B or 568A). Bring all of the wires together, until they touch.
4. At this point, recheck the wiring sequence with the diagram.
5. Optional: Make a mark on the wires at 1/2" from the end of the cable jacket.

6. Hold the grouped (and sorted) wires together tightly, between the thumb, and the forefinger.
7. Cut all of the wires at a perfect 90 degree angle from the cable at 1/2" from the end of the cable jacket. This is a very critical step. If the wires are not cut straight, they may not all make contact. We suggest using a pair of scissors for this purpose.
8. Conductors should be at a straight 90 degree angle, and be 1/2" long, prior to insertion into the connector.
9. Insert the wires into the connector (pins facing up).
10. Push moderately hard to assure that all of the wires have reached the end of the connector. Be sure that the cable jacket goes into the back of the connector by about 3/16".
11. Place the connector into a crimp tool, and squeeze hard so that the handle reaches it's full swing.
12. Repeat the process on the other end. For a straight through cable, use the same wiring. For a "crossover" cable, wire one end 568A, and the other end 568B.
13. Use a cable tester to test for proper continuity.

Optical Fiber Cable

Fiber-optic media (or optical-fiber, or fibers, for short) are any network-transmission media that use glass, or in some cases, plastic, fiber to transmit network data in the form of light pulses. Within the last decade, fiber optics has become an increasingly popular type of network transmission media.

Fiber Optic Cable

The following advantages of fiber over other cabling systems explain why it is currently enjoying popularity as a network-cabling medium:

• Immunity to electromagnetic interference (EMI)
• Higher data rates
• Longer maximum distances
• Better security

Type of Fiber

Once light enters an optical fiber, it travels in a stable state called a mode. There can be from one to hundreds of modes depending on the type of fiber. Each mode carries a portion of the light from the input signal.

Generally speaking, the number of modes in a fiber is a function of the relationship between core diameter, numerical aperture, and wavelength. Every telecommunications fiber falls into one of two categories: single-mode or multimode.

    

1)    Single-mode - allows for only one pathway, or mode, of light to travel within the fiber. The core size is typically 8.3 µm. Single-mode fibers are used in applications where low signal loss and high data rates are required, such as on long spans where repeater/amplifier spacing needs to be maximized.

Single Mode Fiber

2)    Multimode - allows more than one mode of light. Common MM core sizes are 50 µm and 62.5 µm. Multimode fiber is better suited for shorter distance applications. Where costly electronics are heavily concentrated, the primary cost of the system does not lie with the cable. In such a case, MM fiber is more economical because it can be used with inexpensive connectors and LED transmitters, making the total system cost lower. This makes MM fiber the ideal choice for short distance, lower bandwidth applications.

Multi Mode Fiber

There is a lot of connector that available for Fiber Optic:

Legend:

LC - Lucent Connector

SC - Subscriber Connector

FC - Fix Connection

ST - Straight Tips Connector

Coaxial Cable

Coaxial cables may be rigid or flexible. Rigid types have a solid sheath, while flexible types have a braided sheath, usually of thin copper wire. The inner insulator, also called the dielectric, has a significant effect on the cable's properties, such as its characteristic impedance and its attenuation. The dielectric may be solid or perforated with air spaces. Connections to the ends of coaxial cables are usually made with RF connectors.

Coaxial Cable

There is 2 type of coaxial cable that is commonly used :

1)    Thin coaxial cable – 2.5C 2V (Speed Of 2Mbps)

2)    Thick coaxial cable – 3C 2W (Speed of 34Mbps)

Coaxial Connectors

There is a lot of coaxial connector available at the market. 2 of the commonly used are:

1)    BNC (Bayonet Neill-Concelman) - type of RF connector used for terminating coaxial cable.

                                                    Male Connector      
                                        

                                                        Female Connector

2) L-Shape Connector – Consist of Male connector (used as a jumper on DDF) and Female connector (used at DDF to connect with male jumper).

L-Shape Connector

            Other Cable Connection

1)    G.703 Cable - G.703 is a CCITT standard for transmitting voice over digital carriers such as T1 and E1. G.703 provides the specifications for pulse code modulation (PCM) at data rates from 64 Kbps to 2.048 Mbps. G.703 service is typically used for interconnecting data communications equipment such as bridges, routers, and multiplexers.

G.703 Cable

2)    V.35 Cable - is a high-speed serial interface designed to support both higher data rates and connectivity between DTEs (data-terminal equipment) or DCEs (data-communication equipment) over digital lines.  V.35 is connect to NT for a WAN connection.

There are 2 types of V.35 available at market:

·        
                    V.35 (Serial Type)

·                    V.35 (Smart Serial)