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TOPIC 1.2

TOPIC 1.2. INTRODUCTION TO NETWORKING. OBJECTIVES. By the end of the topic, students should be able to: List the elements of data communication systems. Describe the communication devices: Wired Wireless Describe basic data transmission concepts

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TOPIC 1.2

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  1. TOPIC 1.2 INTRODUCTION TO NETWORKING

  2. OBJECTIVES • By the end of the topic, students should be able to: • List the elements of data communication systems. • Describe the communication devices: • Wired • Wireless • Describe basic data transmission concepts • Define common transmission flaws affecting data signals. • Define rules of communications • Explain the signal transmission

  3. DATA COMMUNICATION SYSTEM ELEMENTS • Data Elements • Communication Devices • Electronic Communication Methods • Transmission Media

  4. DATA ELEMENTS • Message • Sender • Receiver • Medium • Protocol

  5. COMMUNICATION DEVICES • A hardware component that enables a computer to send and receive data, instructions and information and from one or more computers. • Type of communication devices: • Wired (Data Terminal Equipment (DTE)) • Wireless (3G,GPRS, laptop, mobile phones)

  6. COMMUNICATION DEVICES • Wired • Serial Wires are used for high end connectivity between different devices and widely used on layer 3. • DTE ( data terminal equipment) and DCE (data circuit-terminating equipment / data communications equipment). • Ethernet Cables (UTP) • How many types of Ethernet?

  7. COMMUNICATION DEVICES • Wireless Devices

  8. COMMUNICATION DEVICES • REPEATER ~ increasing the signals energy • HUB / SWITCH • Centralizing connection for all network devices • Sending packets using MAC address • BRIDGE ~ Connecting two or more different networks for communication • ROUTER ~ Forwarding packets in the network using MAC and IP address • GATEWAYS ~ a device that acts as a “MAIN PATH” for all network traffics

  9. Electronic communication methods • Email • Instant Messaging

  10. Transmission media • Guided Media • Twisted-Pair Cable • Coaxial Cable • Fiber Optic Cable • Unguided Media: Wireless • Transport electromagnetic waves without using a physical conductor

  11. Transmission media • Twisted-Pair Cable • Color-coded pairs of insulated copper wires twisted around each other and encased in plastic coating • Twists in wire help reduce effects ofcrosstalk • Number of twists per meter or foot known as twist ratio • Alien Crosstalk • When signals from adjacent cables interfere with another cable’s transmission

  12. Shielded Twisted-Pair (STP) • STP cable consists of twisted wire pairs that are individually insulated and surrounded by shielding made of metallic substance

  13. Unshielded Twisted-Pair • Consists of one or more insulated wire pairs encased in a plastic sheath • Does not contain additional shielding • To manage network cabling, it is necessary to be familiar with standards used on modern networks, particularly Category 3 (CAT3) and Category 5 (CAT5)

  14. Comparing STP and UTP • Throughput • Both can transmit up to 100 Mbps • Cost • Typically, STP is more expensive • Connector • Both use RJ-45 connectors (see Figure 4-27) and data jacks • Noise immunity • STP is more noise-resistant • Size and scalability • Maximum segment length for both is 100 meters

  15. Fiber-Optic Cable • Contains one or several glass fibers at its core • Surrounding the fibers is a layer of glass called cladding

  16. Single-mode fiber • Carries light pulses along single path • Multimode fiber • Many pulses of light generated by LED travel at different angles

  17. Unguided Media: Wireless • Infrared transmission • Infrared networks use infrared light signals to transmit data through space • Direct infrared transmission depends on transmitter and receiver remaining within line of sight • In indirect infrared transmission, signals can bounce off of walls, ceilings, and any other objects in their path

  18. RF transmission • Radio frequency (RF) transmission relies on signals broadcast over specific frequencies • Two most common RF technologies: • Narrowband • Spread spectrum

  19. DATA TRANSMISSION CONCEPTS • Analog and digital signaling • Data modulation • Simple, half-duplex and full-duplex • Multiplexing • Point-to-point transmission • Broadcast transmission • Bluetooth, 3G • Throughput • Bandwidth

  20. TRANSMISSION FLAWS • Noise • Occurred when devices act as a sending antenna and the transmission medium act as the receiving antenna. • Attenuation • Loss of signal strength as transmission travels away from source • Analog signals pass through an amplifier, which increases not only voltage of a signal but also noise accumulated An analog signal distorted by noise, and then amplified

  21. TRANSMISSION FLAWS • Latency • Latency is the delay between requesting data and the receipt of a response, or in the case of one-way communication, between the actual moment of a signal's broadcast and the time it is received at its destination • Electromagnetic interference (EMI) • Interference that may be caused by motors, power lines, television, copiers, fluorescent lights, or other sources of electrical activity • Radiofrequency interference (RFI) • Interference that may be generated by motors, power lines, televisions, copiers, fluorescent lights, or broadcast signals from radio or TV towers

  22. TRANSMISSION FLAWS • Distortion • Signal changes its form or shape. • Made of different frequencies. • Regeneration • Process of retransmitting a digital signal • Repeater • Device used to regenerate a signal A digital signal distorted by noise, and then repeated

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