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Networking

Networking. U2M3 Network Devices. Objectives. List the basic network hardware Describe various Transmission Media Explain the function of various network hardware Identify the OSI layer that the equipment resides. OSI layers.

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Networking

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  1. Networking U2M3 Network Devices

  2. Objectives • List the basic network hardware • Describe various Transmission Media • Explain the function of various network hardware • Identify the OSI layer that the equipment resides

  3. OSI layers • Application (Layer 7)Presentation (Layer 6)Session (Layer 5)Transport (Layer 4)Network (Layer 3)Data Link (Layer 2)Physical (Layer 1) • All People Seem To Need Data Processing • Please Do Not Through Sausage Pizza Away

  4. Node • A Node is any device on a network that is accessed directly. • server • workstation • printer • scanner • or any other kind of peripheral • A node has • an unique name or IP address so the rest of the network can identify it.

  5. Physical (Layer 1) –Network devices • Transmission Medium • Connectors • HUBS • Repeaters • Network Cards • Modems • Data Transmission via : electric voltages, radio frequencies, pulses of infrared or ordinary light

  6. Data Flow • Simplex transmission • One direction only • Television and radio • Half-duplex transmission • Both direction – one direction at a time • CB radio, terminal • Full-duplex transmission • Both directions at the same time • Telephone, computer to computer

  7. Timing • Asynchronous transmission • Start/stop bits for character synchronization • Mark (1or stop) /space (0 or start ) bits for bit synchronization • Simple, inexpensive, slow speed transmission • For personal computer • Synchronous transmission • Clock circuitry • One to four synchronization characters for each block of data • Large amount of data on dedicated line

  8. Transmission Medium Any material that is capable of carrying one or more signals • Twisted Pair • Coaxial Cable • Fiber Optics • wireless Signals

  9. Twisted pair cabling Shielded and Unshielded. • Unshielded twisted pair (UTP) • Category 3 - Data to 10 Mbps (Ethernet) • Ethernet specification -10BaseT • Category 4 - Data to 20 Mbps (Token Ring) • Category 5 -Data to 100 Mbps (Fast Ethernet) • Ethernet specification -100BaseT

  10. RJ-45 connector • The standard connector for twisted pair cabling is an RJ-45 connector

  11. Coaxial Cable • Coaxial cabling has a single copper conductor at its centre • Ethernet specification - 10Base2 • resistant to signal interference. • supports greater cable lengths between network devices • Cable television (CATV) network wiring often uses coaxial cable

  12. Bayone-Neill-Concelman (BNC) connector • connector used with coaxial cables • T-connector, • barrel connector • terminator

  13. Fiber optic • consists of a centre glass core surrounded by several layers of protective materials • Ethernet specification -10BaseF • Transmit • light rather than electronic signals • signals over much longer distances • at greater speeds • 100Mbps to 1Gbps.

  14. Fiber Optic Connector • ST connector • It is barrel shaped, similar to a BNC connector • SC connector • It has a squared face

  15. Communications Media Summary • Twisted pair (copper cable) • used in telephone network and LANs • Coaxial cable • high quality, well insulated cable • Fibre optic cable • sends pulses of light rather than electricity • Microwave • almost line of sight (can be up to about 30 miles apart) • Communications satellite • in geosynchronous orbit (rotating at the same speed as earth, therefore stationary relative to Earth)

  16. FireWire • FireWire also known as IEEE 1394 • transfers information between digital devices, especially audio and video equipment. • is fast -- speeds up to 800 Mbps.

  17. WIRELESS TRANSMISSION MEDIA • Wireless Transmission media send communication signals through air or space using radio, microwave, and infrared signals. • Has a transceiver/antenna to send and receive the data. • Advantage • more convenient than installing cables • where installing cables are impossible. • The wireless transmission media • Satellite • Microwave • Wireless fidelity (WiFi)

  18. Satellite • This makes connectivity available via satellites that orbit the earth • provides access to users in remote areas

  19. Satellite • A communication satellite is a space station that receives microwave signals from an earth-based station, amplifies (strengthens) the signals, and broadcasts the signals back to earth over a wide area to any number of earth-based stations. • The earth-based stations - • microwave stations. • smart phones • GPS receivers,

  20. Satellite • Communication satellite’s transfer data rate is 1Gbps. • Uplink is the transmission from an earth-based station to a satellite. • Downlink is the transmission from a satellite to an earth-based station.

  21. Microwave

  22. Microwaves • Microwaves are radio waves that provide a high-speed signal transmission • maximum rate of 150 Mbps • use line-of-sight transmission • fixed wireless, involving sending signals from one microwave station to another.

  23. WiFi • IEEE 802.11x. • 802.11a, • up to 54 Mbps • Uses 5 GHz range • 802.11b , • 11 Mbps • Uses 2.4 GHz range • Interference • 802.11g, • 54 Mbps • Uses 2.4 GHz range • 802.11n • over 100 Mbps • multiple wireless signals and antennas (MIMO technology)

  24. Hubs • A hub is central device that (seldom still used today) • provides a common connection point for nodes on the network. • broadcast messages

  25. Hubs - Functions • When a signal is sent from a computer, it is • received by the hub • make a clean, strong copy of the signal. • Broadcast • Retransmitted to all other computers connect to it. • accepted only by computer the signal is addressed.

  26. Hubs - Issues / Disadvantages/ Problems • If the hub goes down, the whole network goes down. • Broadcasting messages • slow down network • generate lot of traffic • Lowers security

  27. Repeater • Amplifies the input signals and retransmits. • It Is used to extend the range of a network segment.

  28. Network Interface Card • NICs play an important role in connecting a computer to the physical part of the network

  29. Modem • A modem (Modulator DEModulator) is a device that modulates an analogue carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information.

  30. Types Modem Connections Telephone service • Dial-up Modems Broadband Telephone Service • Integrated Services Digital Network (ISDN) • DSL (Digital Service Line) TV service • Cable modem

  31. Dial-up Modems • Features • Analogue • dial-up connections • normal phone lines • dial-up service • data rate up to 56 Kbps • voice or data • on the phone or internet • Connect drops when phone rigns

  32. Integrated Services Digital Network (ISDN) • Features • dial-up service • Digital • special ISDN telephone line • Data rate use 64Kpbs channels • combined channels for higher speeds.

  33. Digital Service Line (DSL) • Features • Digital • Telephone lines • Always connected • Data rate up to 6 Mbps • Use both data and voice (be on the phone and internet)

  34. Cable modem • Features • Analogue or digital • Uses coaxial cable • Always connected • data rate up to 30 Mbps

  35. Data Link (Layer 2) • Network Interface Card • Switches – uses MAC address • Bridges

  36. Network Interface Card • a NIC operates at both layer 1 and Layer 2. • At Layer 2 • the NIC MAC address are used by switches to make connections between nodes

  37. Switches • A switch is a network device that connects a number of computers together to make a LAN. • Function • each computer has its cables plugged into it • on receiving a message, it checks who it is addressed to, and only sends it to that specific computer.

  38. Switches • Is an ‘intelligent’ device • Compared to a hub • networks that use switches are more secure than those that use hubs, • more expensive than hubs. • The typical use of a switch • At the centre of a star network (or as part of a hybrid network)

  39. Bridge • A bridge is a network device that typically links together two different parts of a LAN.

  40. Bridge Functions • analyze incoming data packets • Determine which segment of the network to send the given packet. • filters data traffic at a network boundary • reduce the amount of traffic on a LAN • divided into two segments

  41. Network (Layer 3) • Routers - uses the IP address • Layer Three switches (brouter)

  42. Routers A network device that • is used to connect together two or more networks. • a LAN to a WAN

  43. Router Functions • forwards data packets across and between computer networks. • different from a switch which works within a single network • selects the fastest available path • For data packets to reach their destination • allows multiple computers to share a single high-speed (Internet) connection

  44. Routers • A wireless router is a router and wireless switch combined. • It links a wireless LAN to a WAN

  45. Transport (Layer 4) • Gateways • Proxy Server • Firewalls

  46. Transport (Layer 4) • Gateways • Proxy Server

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