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Network Connectivity (Topic 2)

Network Connectivity (Topic 2). Textbook: Networking Basics, CCNA 1 Companion Guide , Cisco Press Cisco Networking Academy Program, CCNA 1 and 2, Companion Guide , Cisco Press, Latest Edition. Analog Signal Vs Digital Signal. Analog data is continuous data

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Network Connectivity (Topic 2)

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  1. Network Connectivity(Topic 2) Textbook: Networking Basics, CCNA 1 Companion Guide, Cisco Press Cisco Networking Academy Program, CCNA 1 and 2, Companion Guide, Cisco Press, Latest Edition CIM 2465 Network Connectivity

  2. Analog Signal Vs Digital Signal • Analog data is continuous data • The world we live in is mainly an analog world. E.g. light, video, voice • Digital data is discrete, values are distinct from one another. • Digital computers process data in digital form (0 or 1) • A/D D/A conversion (e.g. modem) CIM 2465 Network Connectivity

  3. Analog Signal Vs Digital Signal CIM 2465 Network Connectivity

  4. Properties of an Analog Signal • Amplitude • Frequency • Phase • Modulation and Demondulation CIM 2465 Network Connectivity

  5. Factors AffectingTransmission of Signals • Noise • Refers to any interference on the physical medium that makes it difficult for the receiver to detect the data signal • Crosstalk • Noise created on one wire as a result of current flowing over a nearby wire • Attenuation • Attenuation in an electrical signal is a decrease in voltage as the signal crosses the wire • Can be caused by • Resistance of wires • Energy loss • Frequency of signal CIM 2465 Network Connectivity

  6. CIM 2465 Network Connectivity

  7. Digital Transmission • Digital Transmission is a general term that refers to how computing devices transmit the binary bits from one to another • Can be done by (Modulation) • Varying (modulating) an electrical signal as it passes over a copper wire • Varying the power of light as sent over an optical fiber • Varying the radio waves sent through space, wireless communications CIM 2465 Network Connectivity

  8. Transmission Media • Major types • Copper Wires • Coaxial Cable, Shielded Twisted Pair (STP), Unshielded Twisted Pair (UTP) • Optical • Wireless • Considerations • Transmission speed • Digital or Analog transmission • Transmission distance CIM 2465 Network Connectivity

  9. Coaxial Cable • Composed of a single copper wire, surrounded by an insulating shell, then a second conductor shield, and a plastic outer shell • Types: • Thick Coaxial (10Base5) • Thin Coaxial (10Base2) • Today’s modern LANs no longer use 10BASE5 and 10BASE2 CIM 2465 Network Connectivity

  10. Coaxial Cable • Advantages • Longer transmission distance than STP and UTP, fewer repeaters needed • Less expensive than fiber-optic, more expensive than STP and UTP • High bandwidth medium that can carry thousands of signals, support broadband transmission of cable TV, a single cable is divided into many channels for transmission. Commonly used to deliver cable-television signals and high-speed Internet access CIM 2465 Network Connectivity

  11. Coaxial Cable CIM 2465 Network Connectivity

  12. Twisted Pair Wire • Most commonly used data transmission medium • Its core consists of pairs of copper wires twisted together to create magnetic field and thus reduce interference • 2 types: • Shielded Twisted Pair (STP) • Unshielded Twisted Pair (UTP) CIM 2465 Network Connectivity

  13. Shielded Twisted Pair (STP) CIM 2465 Network Connectivity

  14. Shielded Twisted Pair (STP) • Shielding provides a cleaner electrical current by reducing attenuation and noise, thus longer cabling lengths • More expensive, heavier, and difficult to bend when installing them (compare with UTP) CIM 2465 Network Connectivity

  15. Unshielded Twisted Pair (UTP) • Grouped into categories based on quality • Generally used in LAN • Cat 5 cable • RJ45 connector CIM 2465 Network Connectivity

  16. Unshielded Twisted Pair (UTP) • Adv • Does not require grounding like STP, easier to add connectors • Thinner, more flexible to install • Same data speeds as other copper media • Disadv • More susceptible to electrical noise and interference • Shorter cabling distance (100m when used for Ethernet LANs) CIM 2465 Network Connectivity

  17. Twisted Pair Wire • Advantages • Commonly available and relative low cost, especially where telephone lines have already been installed • Disadvantages • Subject to signal distortion, noise and interference, and the relatively low transmission rates CIM 2465 Network Connectivity

  18. Fiber Optic Cable • Thin wire (usually very pure glass or plastic) surrounded by a reflective cladding that is used to transmit optical signals (light) • Copper wire cables transmit signals electrically, whereas fiber-optic cables transmit signals by means of light • More expensive than copper wires, more skill to install CIM 2465 Network Connectivity

  19. Fiber Optic Cable CIM 2465 Network Connectivity

  20. Fiber Optic Cable • Not susceptible to lightning, electromagnetic interference (EMI), or radio frequency interference (RFI), and does not generate EMI or RFI • Much greater bandwidth • Greater transmission distances • Excellent signal quality CIM 2465 Network Connectivity

  21. Fiber Optic Cable • More secure (difficult to tap) • Thin, requires little space in a conduit • Lightweight, easy to install • Better resistance to environment factors, e.g. water • Generally used to link LANs, WANs, or as backbone of large networks CIM 2465 Network Connectivity

  22. Fiber Optic Cable • Fiber Optics Types: • Multi-mode cable • Less expensive • Less expensive LED transmitters are used • Larger core, multiple angles of entry • Single-mode cable • More expensive • More expensive laser transmitters are used • Significant longer cabling distances • Skinny core, only one angle of entry CIM 2465 Network Connectivity

  23. Fiber Optic Cable CIM 2465 Network Connectivity

  24. Wireless Media (1) • Infrared • Radio wave • Bluetooth • Wifi • Mobile Phone network (e.g. GSM, 3G) • Microwave • Satellite CIM 2465 Network Connectivity

  25. Wireless Media (2) • WLAN Components • PCs with WLAN NICs • Access Points (APs), which act as a LAN hub for wireless devices • Infrastructure mode • Uses APs, with the PCs sending and receiving data to and from the AP • Ad-hoc mode • Formed by any two wireless devices, find and associate with each other CIM 2465 Network Connectivity

  26. Wireless Media (3) • To install a WLAN that works with the existing LAN infrastructure • At least one AP • A straight-through cable to connect AP to an existing LAN switch • Wireless NICs in end-user devices to communicate with the APs CIM 2465 Network Connectivity

  27. CIM 2465 Network Connectivity

  28. Wireless Media (4) • WLAN Organization and Standards • IEEE defines WLAN standards 802.11 • Wi-Fi alliance (www.wi-fi.org) CIM 2465 Network Connectivity

  29. LAN Cabling • Considerations • Ethernet Types • Media • Speed • Distance • Connector CIM 2465 Network Connectivity

  30. LAN UTP Cabling Standards CIM 2465 Network Connectivity

  31. Ethernet LAN Media and Connectors CIM 2465 Network Connectivity

  32. UTP Cable Pinouts • Key concepts • Ethernet devices (at 10 and 100Mbps Ethenet) use one pair of wires to transmit data • Ethernet devices (at 10 and 100Mbps Ethenet) use another pair of wires to receive data • Two pairs of wires are required • Types • Straight-Through Cable • Crossover Cable • Console Connection and Rollover Cable CIM 2465 Network Connectivity

  33. Straight-Through Cable • To connect an end-user device and a LAN hub or switch • PC’s NIC uses • Pin 1, 2 to transmit • Pin 3, 6 to receive • LAN hubs, switches (the other end) • Pin 3, 6 to transmit • Pin 1, 2 to receive CIM 2465 Network Connectivity

  34. Straight-Through Cable • TIA/EIA-T568-B or A on BOTH ends of the cable CIM 2465 Network Connectivity

  35. TIA/EIA 568-A CIM 2465 Network Connectivity

  36. Crossover Cable • To connect two devices that both want to send on the same pins (two devices of similar ‘type’, e.g. two PCs) • BOTH sides use • Pin 1, 2 to transmit • Pin 3, 6 to receive CIM 2465 Network Connectivity

  37. Crossover Cable • One side is T568-A and T568-B one the other (10BaseT, 100BaseT) • Special arrangement for 1000BaseT CIM 2465 Network Connectivity

  38. How to choose? • Two groups of devices • PC, router, server, AP (use pins 1 and 2 to transmit) • Switch, hub, bridge, repeater (use pins 3 and 6 to transmit) • When connecting two devices that are similar in regard to which pins they use to transmit, use a crossover cable • e.g. Switch to Switch, Switch to Hub, Hub to Hub, Router to Router, PC to PC, Router to PC • When connecting two devices that differ in regard to which pins they use to transmit, use a straight-through cable • e.g Switch to Router, Switch to PC, Hub to PC CIM 2465 Network Connectivity

  39. CIM 2465 Network Connectivity

  40. Basic Models for PC Communications (1) • Peer-to-peer • A computer acts as a peer with other computer by acting both as a client and a server • E.g. Sharing a folder in a Windows workgroup • Adv • Simple to install • No special hardware required • Most OS support peer-to-peer networking • No network administrators required • Disadv • Security • Loss control CIM 2465 Network Connectivity

  41. Basic Models for PC Communications (2) • Client/Server • A computer acts as either a client or a server • Server usually is more powerful, and requires a more expensive network operating system (NOS) • Adv • Centralized control • Security control • Easier data backup • Disadv • Cost • Network administrators required • If server fails, …. CIM 2465 Network Connectivity

  42. CIM 2465 Network Connectivity

  43. Comparing Peer-to-Peer and Client/Server CIM 2465 Network Connectivity

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