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Free Powerpoint Templates Page 1Free Powerpoint Templates
Network Transmission
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Link
• Refers to the way the devices are connected by a link. A link is physical or wireless connection between one or more devices.
• Point-to-Point– Dedicated link between two devices.– Whole capacity of the channel is reserved.– Uses actual length of wire or cable to connect two ends.– Microwave or satellite links can be established.– Examples:
Connection of devices in mesh topology. Connection between remote control and operating device such as CD player, television set, home theater etc.
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Link
• Point-to-Multipoint– More than two devices share the same link.– Capacity of channel is shared spatially or temporarily.– Allows broadcasting packets over the network.– Each device is able to communicate with each other.– Examples:
A radio station. Video Conference.
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Transmission Modes
• Transmission modes defines the direction of data transmission between two connected devices.
• Simplex– Its a one-way communication, where data flows only in one
direction from sender to receiver.– Eg. Televisions, radios.
• Half-Duplex– Its a two-way communication, data flows in both direction but
sender and receiver can't transmit and receive at the same time.– E.g.: Walkie-talkies, Citizen Band (CB) radios.
• Full-Duplex– Its a two-way communication, where both sender and receiver can
trasmit and receive at the same time.– E.g.: Telephone talk, client and server communication.
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Baseband & Broadband
• Baseband Digital signals are used
Frequency division multiplexing is not possibleBaseband is bi-directional transmissionShort distance signal travellingEntire bandwidth of the cable is consumed by a single signal
in a baseband transmission. • Broadband
Analog signals are usedTransmission of data is unidirectionalSignal travelling distance is longFrequency division multiplexing is possibleThe signals are sent on multiple frequencies and allow all the signals are sent simultaneously in broadband transmission.
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Transmission Media
• Pathway through which individual systems are connected to route data signals in a network.
• Transmission media makes it possible to transmit electronic signals from one computer to another
• These signals are nothing but binary pulses.• Each type of transmission media varies in its characteristics, that
makes it suitable for a specific type of service.• There are Two type of transmission media :
– Unguided transmission media– Guided transmission media
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Unguided transmission media
• No physical connection between source and destination, instead they use air itself. These connections are not bounded to a channel to follow.
• There are two basic types of primary technologies used.• Microwaves
– Travels in straight lines and therefore narrowly focused concentrating all the energy into a beam.
– Periodic repeaters are necessary for long distances.– For transmitting and receiving, antennas should be aligned
accurately.– Can not penetrate through buildings.– Best example is Bluetooth technology.
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Unguided transmission media
• Satellite– Uses microwave radio to prevent from atmosphere and act as
microwave relay station.– They are situated in space 22,000 miles above the equator.– It appears stationary from the earth as it rotates with specific
speed.– They can amplify and relay microwave signals from one
transmitter on the ground to another.– Capable of receiving, relaying of voice, data, and TV signals.– Bad weather can affect the communication.
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Guided transmission media
• Consists of physical connection between source and destination via a wire or a cable. These connections are bounded to a channel to follow.
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Twisted Pair
• Twisted pair cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources; for instance, electromagnetic radiation from unshielded twisted pair (UTP) cables, and crosstalk between neighboring pairs.
• It was invented by Alexander Graham Bell.
• Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source.
• Crosstalk (XT) is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, inductive, or conductive coupling from one circuit, part of a circuit, or channel, to another.
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UTP
• 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 six categories of wire (additional categories are emerging).
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This is the Connector
This is the Jack
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568B pin assignments – straight cable
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Cross Over cable – pin assignments
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Use straight-through cables for… •Switch to router •Switch to PC or server •Hub to PC or server
Use crossover cables for…•Switch to switch •Switch to hub •Hub to hub •Router to router •PC to PC •Router to PC
Use roll-over cables to… •Connect a terminal to a console port
Interconnecting Devices
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Summary Of UTP cable Features
• Speed and throughput—10 to 1000 Mbps• Average cost per node—Least expensive• Media and connector size—Small• Maximum cable length—100 m (short)
Advantages– Relatively inexpensive.– Easily installed, managed, and reconfigured.– Basic technology and standards are matured and stable.
Disadvantages– Only categories 5, 5e and 6 UTP cables are – capable of high-speed data transmission.– Relatively high rate of attenuation.– Sensitive to EMI and eavesdropping.
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STP
• Each pair of wires is individually shielded with foil. • There is a foil or braid shield inside the jacket covering all wires (as a
group). • There is a shield around each individual pair, as well as around the
entire group of wires (referred to as double shield twisted pair).
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Summary of STP Cable Features
• Speed and throughput—10 to 100 Mbps• Average cost per node—Moderately expensive• Media and connector size—Medium to large• Maximum cable length—100 m (short)Advantages
– Technology and standards are fairly proven and stable.– Considerable reduction in EMI.
Disadvantages– More costlier than UTP and harder to install than UTP and
coaxial cables.– Unsuitable for gigabit speed.– Relatively high rate of attenuation.
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Coaxial cable
• Coaxial cable is called "coaxial" because it includes one physical channel that carries the signal surrounded (after a layer of insulation) by another concentric physical channel, both running along the same axis.
• The outer channel serves as a ground. Many of these cables or pairs of coaxial tubes can be placed in a single outer sheathing and, with repeaters, can carry information for a great distance.
• Coaxial cable was invented in 1929 and first used commercially in 1941. AT&T established its first cross-continental coaxial transmission system in 1940.
A. Outer plastic sheath
B. Woven copper shield
C. Inner dielectric insulator
D. Copper core
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BNC Connectors for CCTV Cameras
2 Way Coaxial CATV Cable TV Antenna RF Signal Splitter
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Summary of coaxial cables Features
• Speed and throughput—10 to 100 Mbps• Average cost per node—Inexpensive• Media and connector size—Medium• Maximum cable length—500 m (medium)Advantages
• Relatively simple to install. • Resists EMI better than twisted pair.• Relatively sturdy.
Disadvantages • Moderately susceptible to EMI and eavesdropping• More expensive than Cat 3 UTP.• Outdated technology.
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Fiber Optic Cables
• Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials.
• 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.
• Fiber optic cables have 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
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Fiber Optic Cables
• The center core of fiber cables is made from glass or plastic fibers. A plastic coating then cushions the fiber center, and Kevlar fibers help to strengthen the cables and prevent breakage. The outer insulating jacket is made of Teflon or PVC.
• There are two common types of fiber cables – Single mode Fiber– Multimode Fibers
• Common types of optical fiber cables include:– 8.3 micron core / 125 micron cladding single-mode – 62.5 micron core / 125 micron cladding multimode– 50 micron core / 125 micron cladding multimode – 100 micron core / 140 micron cladding multimode
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Difference between Single mode and Multi Mode Fibers
Single Mode (SM) Fiber Multimode (MM) Fiber
High capacity. Lesser capacity than Single mode.
More costlier than MM fiber. Cheaper than SM fiber.
Light pulses are generated by injection laser diodes (ILDs).
Light pulses are generated by light emitted diodes (LEDs).
Transmission rate of 100 Mbps at distance of 80/90 kilometers.
Can sustain a transmission rate of 100 Mbps at a distance of 2 kilometers.
Optimized to allow one light path.
Optimized to allow multi light paths
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• Connectors are attached to the fiber ends so that the fibers can be connected to the ports on the transmitter and receiver.
• The type of connector most commonly used with multimode fiber is the Subscriber Connector (SC connector).On single-mode fiber, the Straight Tip (ST) connector is frequently used
Fiber Optic Connector
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Media Converter
• Media Converters connect Ethernet-based devices over Fiber and provide reliable extension of multimode to single mode or multimode to multimode fiber.
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OTDR
• Optical Time Domain Reflectometer, an instrument that analyzes the light loss in an optical fiber in optical network trouble shooting.
• An OTDR injects a short, intense laser pulse into the optical fiber and measures the backscatter and reflection of light as a function of time. The reflected light characteristics are analyzed to determine the location of any fiber optic breaks or splice loses .
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Splicing
• Fiber splicing is the process of permanently joining two fibers together. Unlike fiber connectors, which are designed for easy reconfiguration on cross-connect or patch panels.
• There are two types of fiber splicing – mechanical splicing and fusion splicing.
• Mechanical splicing doesn’t physically fuse two optical fibers together, rather two fibers are held butt-to-butt inside a sleeve with some mechanical mechanism.
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Splicing
• The second type splicing is called fusion splicing. In fusion splicing, two fibers are literally welded (fused) together by an electric arc.