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Network access

Network access. Chapter 4 Intro to Routing & Switching. objectives. Upon completion of this chapter, you should be able to: Describe the purpose of the physical layer Identify characteristics of copper cabling Make a UTP cable Describe fiber optic cabling & its advantages

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Network access

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  1. Network access Chapter 4 Intro to Routing & Switching

  2. objectives • Upon completion of this chapter, you should be able to: • Describe the purpose of the physical layer • Identify characteristics of copper cabling • Make a UTP cable • Describe fiber optic cabling & its advantages • Describe wireless media • Select the appropriate media to connect devices • Describe the data link layer, its purpose & structure of a frame • Compare logical & physical topologies • Describe media access control

  3. Physical & data link layers • What does the data link layer do to help send data? • What does the physical layer do to help send the data? • What does the physical layer do to help receive data? • What does the data link layer do to help receive data?

  4. 4.1.1 Getting it connected

  5. Connecting to the network • Connect wired or wirelessly • Switch, WAP, or ISR

  6. Network interface cards • How do you connect to a wired network? • NIC • How do you connect to a wireless network? • WLAN NIC • What are disadvantages of wireless? • Distance from WAP (can use extender) • Sharing of wireless signal (more=slower)

  7. 4.1.2 Purpose of the physical layer

  8. Osi & communication

  9. media • Copper • Electrical pulses • Fiber • Light • Wireless • Radio waves • All follow standards so they can communicate together • ISO (RJ-45), EIA/TIA (568B), IEEE (802.3, 802.11), and others

  10. Lab 4.1.2.4 • Identify network devices & cabling

  11. review

  12. review

  13. 4.1.3 Fundamental Principles of layer 1

  14. Physical layer • Physical components • Cabling, NICs, connectors, ports/interfaces • Encoding • Pattern of voltage for 1’s & 0’s • Differentiates data from control bit info • The patterns indicate start & end of frame • Signaling • It’s what represents a 0 or 1/like Morse code • Volts/no volts; short pulse of light/long; type of radio wave • Random timing between signals (Asynchronous) or set time (clock) between signals (synchronous)

  15. bandwidth • Speed/capacity a media can handle • Like size of a hose • Bigger hose= more water through it

  16. throughput • Measure of transfer of bits over a time • Varies on amount & type of traffic, latency (delay) • Can only be as fast as the slowest link

  17. goodput • The measure of usable data transferred over a given period of time. • Throughput - traffic overhead • Example: • Ethernet is 100Mbps • Throughput is 85Mbps • If traffic overhead is 15Mbps, then goodput is 70Mbps

  18. Types of media • What’s the difference? • Type of copper cabling • Bandwidth it can handle • Type of connectors used • Wiring order & colors • Max distance

  19. activity

  20. Review • GCIT’s Ethernet is 1000Mbps. It’s throughput is 800Mbps. If overhead is 10Mbps, what is the goodput? • 790Mbps • Why are encoding methods (patterns for the bits) used by the physical layer? • So the code can be recognized • Distinguishes data from control bits • Tells where frame starts and ends • An asynchronous signal means what? • No clock signal sent

  21. review • Morse code & the timing between the bits is known as what? • Signaling • The speed or capacity of your media is what? • Bandwidth • The actual amount of bits/data that can actually pass over a period of time is what? • Throughput • The more bandwidth you have, the more __________________ you should have. • Throughput

  22. 4.2.1 Copper cabling introduction

  23. Copper media • Inexpensive & easy to install • Look up a box of Cat 5e 500ft spool • Electrical pulses • Distance limit (attenuation) • Interference from EMI/RFI, crosstalk • To avoid problems, select the right cable for the right situation

  24. Copper cabling • UTP, STP, Coaxial

  25. Utp- quick overview • Most common • RJ-45 connectors • 8 wires, 4 twisted pairs • Twisting prevents crosstalk • Color coded

  26. Stp- quick overview • Better EMI/RFI protection • More expensive to buy & install • RJ-45 • 8 wires, 4 twisted pair wrapped in foil

  27. Coaxial- quick overview • Used in very early Ethernet & now for TV • Wireless antenna connections • Cable Internet • Shielding • Thicker cable • BNC or F-connector

  28. Copper media safety • Flammable • Electrical hazard; attracts lightning

  29. activity

  30. review • What in the ceiling could “mess up” the electrical signal in an UTP cable? • Lights, electrical boxes/equipment • Radio waves cause what kind of interference? • RFI • An electrical motor near a UTP cable causes what kind of interference? • EMI • Signals from one cable jump into another. What problem is this? • Crosstalk

  31. review • Excessively long cable runs cause what problem? • Attenuation, signal gets weaker • What is the solution to prevent crosstalk? • Twisting of the pairs • Which cables have shielding? • STP & coaxial • What kind of connector is on UTP & STP? • RJ45

  32. 4.2.1 Copper cabling

  33. utp • What does the twisting do? • No shielding so it relies on cancellation • Wires are paired for this & twisted a certain distance apart • RJ45 connector

  34. utp • Cat 3, 5/5e, 6 • Based on bandwidth rates

  35. Types of utp cables • Straight-through • We’re going to make them • Crossover • We’re going to make them • Rollover (Cisco’s) • Connect to console port • 568B to reverse

  36. Making utp cables • TIA/EIA 568A & 568B

  37. Straight-through cable • 568B to 568B • Connect unlike devices • Computer to Hub/Switch • Switch to router port • On the PC NIC • Pins 1 & 2 transmit • Pins 3 & 6 receive

  38. Straight-through cable • Straight-through • 568B to 568B • White-Orange • Orange • White-Green • Blue • White-Blue • Green • White-Brown • Brown

  39. Crossover cable • 568A to 568B • Like Devices • Switch/hub port to switch/hub port • Router port to router port • PC to router port • PC to PC

  40. Crossover cable • Crossover • 568B to 568A • Change Oranges & Greens on ONE SIDE! • White-Green • Green • White-Orange • Blue • White-Blue • Orange • White-Brown • Brown

  41. review • What is the 568B color order? • Wor/Or, WGr/Bl, WBl/Gr, WBr/Br • For speeds of 1000Mbps or more, what Category cable should be used? • Cat 6 • What cable… • Goes between same devices? • Crossover • Goes from PC to switch? • Straight through • Goes from serial to console port? • Rollover

  42. review • What colors do you change for a crossover cable? • Oranges & greens • What pairs transmit? • 1 & 2 • What pairs receive? • 3 & 6

  43. 4.2.3 Fiber optic cabling

  44. Fiber optic • Transmits pulses of light • Laser or LED • Used for long distance • Glass or plastic • No EMI/RFI; no lightning attraction • High speed • LAN backbone • Connect ISP to Internet • 2 fibers cables used • Transmit & receive

  45. Fiber optic types • Multimode • LED • Many paths of light • Used in LANs/Campuses • 2000 meters • Less $, used more • Single Mode • Laser light • Single path of light • Connects backbone/NOCs • 3000 meters • More $, faster speed

  46. Fiber connectors/patch cables

  47. Activity- Use LOW or HIGH

  48. activity

  49. review • Which cable is more expensive, copper or fiber? • Fiber • Which cable allows data to travel further, copper or fiber? • Fiber • Why are two strands of fiber used for communication? • Light can only travel in one direction at a time. This will allow for full-duplex.

  50. review • What signal travel on a single-mode cable? • Laser • Which cable would be used to go further distances? • Single mode • Why would you use fiber between buildings rather than copper? • Fiber does not attract lightning

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