CABLING...!!!!

What is Network Cabling?

• Cable is the medium through which information usually moves from one network device to another. There are several types of cable which are commonly used with LANs. In some cases, a network will utilize only one type of cable, other networks will use a variety of cable types. The type of cable chosen for a network is related to the network's topology, protocol, and size. Understanding the characteristics of different types of cable and how they relate to other aspects of a network is necessary for the development of a successful network. 

The following sections discuss the types of cables used in networks and other related topics.

• Unshielded Twisted Pair (UTP) Cable
• Shielded Twisted Pair (STP) Cable
• Coaxial Cable
• Fiber Optic Cable
• Cable Installation Guides
• Wireless LANs
• 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.

• 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 tighter the twisting, the higher the supported transmission rate and the greater the cost per foot. The EIA/TIA (Electronic Industry Association/Telecommunication Industry Association) has established standards of UTP and rated six categories of wire (additional categories are emerging).

 

Categories of Unshielded Twisted Pair

Category	Speed	Use
1	1 Mbps	Voice Only (Telephone Wire)
2	4 Mbps	LocalTalk & Telephone (Rarely used)
3	16 Mbps	10BaseT Ethernet
4	20 Mbps	Token Ring (Rarely used)
5	100 Mbps (2 pair)	100BaseT Ethernet
	1000 Mbps (4 pair)	Gigabit Ethernet
5e	1,000 Mbps	Gigabit Ethernet
6	10,000 Mbps	Gigabit Ethernet

 

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. 

Kabel Jenis Shielded Twisted Pair (STP)

Sejenis kabel telefon kuprum yang mempunyai 2 wayar kuprum digabungkan bersama yang disaluti untuk melindungi kabel tersebut.Bahagian yang disaluti melindungi dari gelombang elecktromagnet dari kerosakan kabel.Kerap digunakan dalam Ethernet terutamanya dalam penghantaran data yang laju.

Ia sesuai untuk persekitaran elektrik sebab disaluti lebih tebal kabelnya.Ia menggunakan kuprum kabel untuk menyambungkan komputer dengan syarikat telekomunikasi.Sesuai digunbakan dalam rangkaian Token Ring Topology.

Walaupun STP melindungi ganguan lebih baik dari UTP,ia lebih mahal dan amat sukar untuk dipasang.Ia kerana pelindung yang berkilat (metallic shielding) mesti dibumikan kedua-duanya.Disebabkan kesukaran untuk memasang dan konfigurasi ia jarang digunakan dan hanya di Eropah sahaja lebih digunakan.

Ciri-ciri kabel STP:

• Kelajuan dan keluaran —10 – 100 Mbps
• Purata harga satu node — Mahal
• Saiz media dan sambungan—Sederhana – Besar
• Panjang maksimum —100 m (paling pendek)

 

Coaxial cabling

This is cabling where the central cable that transmits the data is surrounded by a shield of copper braiding. This protects it from interference and so coaxial cabling is found in places such as factories, where there is a lot of possible interference.

Fibre Optic Cabling 

Fibre Optic cales transmit data as pulses of light. The light is reflected along the cable as shown:

A fibre optic cable looks similar to this cable shown below.

Fibre Optic Advantages:

·         It is very difficult to break

·         Does not suffer from electrical or magnetic interference.

·         Transmits at very high speeds.

•          Fibre Optic Disadvantage:

·         Very expensive to buy and install.