NETWORK MEDIA

Computer networks can be classified according to the hardware technology that is used to interconnect the individual devices in the network

  1. Bounded Media (Wired technologies).
  2. Un-Bounded Media (Wireless technologies).

Wired technologies (Cables)

Mainly there are three types of Cables Twisted Pair, Coaxial and Optical fiber.

  1. Twisted pair cables

Twisted pair wire is the most widely used medium for telecommunication. Twisted-pair wires are ordinary telephone’s like wires which consist of certain insulated copper wires twisted into pairs and are used for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction.

  1. UTP (Unshielded Twisted Pair)

UTP cable is the most common cable used in computer networking. Modern Ethernet, the most common data networking standard, utilizes UTP cables. Twisted pair cabling is often used in data networks for short and medium length connections because of its relatively lower costs compared to optical fiber and coaxial cable.

It’s a four pair copper cable combination, have segmentation length 100 meter. The UTP cable has six classifications according to its operation and speed. They are

            Cat 1: The first category cable has only two pairs of copper cable and only has the ability to transfer voice. Cat 1 cable has only 2 mbps speed. And segmentation length is 100 m.

            Cat 2: The cat 2 cables are 4 pair copper cable combination which has the ability transfer both data and voice. Its speed is 4 mbps and segmentation length is 100m

            Cat 3: This category cables are 4 pair copper cable combination which has the ability transfer both data and voice. Speed is 10 mbps. . It is also known as 10Base-T Cable

            Cat 4: It is same as the cat 3 cable but, differ from its speed. Speed is 16 mbps

            Cat 5: Cat 5 cable operates over a bandwidth of 100MHz on UTP and can handle up to 100Mbps over a range of 330 feet (100m). It is also known as 100Base-T.

            Cat 5e: Cat 5e (enhanced) operates over a bandwidth of 100MHz on UTP, with a range of 330 feet (100 m). It has 1000mbps Speed and 22mm gage.

            Cat 6: Cat 6, specified under ANSI/TIA/EIA-568-B.2-1, operates over a bandwidth of up to 400MHz and supports up to 1Gbps over a range of 330 feet (100 m). And have 23mm gage.

2. STP (Shielded Twisted Pair)

STP cabling includes metal shielding over each individual pair of copper wires. This type of shielding protects cable from external EMI (electromagnetic interferences). e.g. the 150 ohm shielded twisted pair cables defined by the IBM Cabling System specifications and used with token ring networks.

3. FTP (Foiled Twisted Pair)

Also known as screened UTP cable (ScTP) or S/UTP

4. S/STP (Shielded STP)

S/STP cabling, also known as Screened Fully shielded Twisted Pair (S/FTP) is both individually shielded (like STP cabling) and also has an outer metal shielding covering the entire group of shielded copper pairs (like ScTP). This type of cabling offers the best protection from interference from external sources.

  • Coaxial Cable

Coaxial cable, or coax, is an electrical cable with an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis. Coaxial cable was invented by English engineer and mathematician Oliver Heaviside, who first patented the design in 1880.

Coaxial cable is used as a transmission line for radio frequency signals, in applications such as connecting radio transmitters and receivers with their antennas, computer network (Internet) connections, and distributing cable television signals. One advantage of coax over other types of transmission line is that in an ideal coaxial cable the electromagnetic field carrying the signal exists only in the space between the inner and outer conductors. This allows coaxial cable runs to be installed next to metal objects such as gutters without the power losses that occur in other transmission lines, and provides protection of the signal from external electromagnetic interference. There are mainly two types of Coaxial cables; they are Thick Net Coaxial and Thin Net Coaxial.

Thin Net Coaxial: Segmentation Length is 185m.

Thick Net Coaxial: Segmentation Length is 500m

Optical Fiber Cable

Optical fiber cable consists of one or more filaments of glass fiber wrapped in protective layers. It transmits light which can travel over extended distances without signal loss. Fiber-optic cables are not affected by electromagnetic radiation. Transmission speed may reach trillions of bits per second. The transmission speed of fiber optics is hundreds of times faster than for coaxial cables and thousands of times faster than for twisted-pair wire. In fiber optic cable two type of data transmission is occurs; they are

 Single Mode and Multi Mode

Cable Crimping:

Crimping is a process, to make suitable cable for communication. UTP cables are mainly used for a LAN Creation.

There are 3 type of arrangement in UTP cable.

  1. Cross-Over
  2. Straight-Though
  3. Roll-Over

Cross-Over: Cross-Over cable category is used to connect similar devices together. The cable will cross the data, from transmitter to receiver and wise versa.

In a UTP cable,

White and Orange       = Transmitter Positive.

Orange                        = Transmitter Negative

White and Green         = Receiver Positive.

Green                          = Receiver Negative.

All Others has No connection in cross-over and straight-through.

Color code for Cross-Over Crimping,

Straight-Through: This cable category is used to connect different devices together like PC to Hub, Hub to Router. Here data crossing was done by devices so that we crimp both cable end as same.

Color Code for Straight-Through,

Wireless Technologies

  • Wireless LANs – Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. An example of open-standards wireless radio-wave technology is IEEE 802.11b.
  • Bluetooth – A short range wireless technology. Operate at approx. 1Mbps with range from 10 to 100 meters. Bluetooth is an open wireless protocol for data exchange over short distances.

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