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OSI Physical Layer

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OSI Physical Layer

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OSI Physical Layer

  1. 1. OSI Physical Layer Network Fundamentals – Chapter 8 ITE I Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 1
  2. 2. Objectives  Identify Physical layer protocols and services in supporting communication across data networks.  Identify Physical layer signaling and encoding as they are used in networks  Identify characteristics and uses of copper, fiber and wireless network media ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 2
  3. 3. Physical Layer Protocols & Services  The Physical layer provides network connectivity and a medium through which network data can travel from source to destination Straight, X-over , Fiber Transmitters, Laptops, VIOP phones ,PDAs, Hubs, Switches, Router ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 3
  4. 4. Physical Layer purpose  The purpose of the Physical layer is to create the electrical, optical, or microwave signal that represents the bits in each frame. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 4
  5. 5. Physical Layer signals  Different media carry signals in different formats ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 5
  6. 6. Physical Layer standards  The Physical layer has it own standards organizations just like other layers •The International Organization for Standardization (ISO) •The Institute of Electrical and Electronics Engineers (IEEE) •The American National Standards Institute (ANSI) •The International Telecommunication Union (ITU) •The Electronics Industry Alliance/Telecommunications Industry Association (EIA/TIA) •National telecommunications authorities such as the Federal Communication Commission (FCC) in the USA. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 6
  7. 7. Physical Layer functions  Three fundamental Functions of the Physical layer The physical components (Hardware) Data encoding (data encoded into predictable codes) Signalling (How data is represented i.e. as light, voltage or electrogmagnetic waves) ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 7
  8. 8. Physical Layer Signaling  Signals can be represented based on their size (Amplitude), Rate (Frequency) or their relative timing to a reference (Phase) ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 8
  9. 9. Physical Layer Encoding  Encoding is the converting of data into voltages, light or electromagnetic signals onto different media types  NRZ and Manchester are two copper based media encoding types for voltages ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 9
  10. 10. Physical Layer Data rates  Bandwidth (Max or Data rate units bps), Throughput (Actual data rate) and Goodput (Useable Data rate) ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 10
  11. 11. Physical media Characteristics  Media characteristics defined by Physical layer standards. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 11
  12. 12. Physical layer Interference and Noise  unwanted signal (interference, noise) can corrupt data on copper based network media and reduce throughput and lead to DOS ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 12
  13. 13. Physical Characteristics of UTP  Characteristics of UTP cable ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 13
  14. 14. Physical Characteristics of Coaxial, STP  Characteristics of Coaxial cable and STP ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 14
  15. 15. Physical media – Safety  Safety issues when working with copper cabling ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 15
  16. 16. Physical media connectors and terminators  Media needs to be correctly terminated with correct connectors ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 16
  17. 17. Physical Media – Fiber optic  Two basic fiber optic cable types Single mode and Multi-mode ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 17
  18. 18. Physical media - Wireless  Radio waves electromagnetically propagate through free space and therefore require security in wireless communications ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 18
  19. 19. Physical Layer –Wireless standards  Standard IEEE 802.11 WiFi Wireless Local Area Network (WLAN), CSMA/CA  Standard IEEE 802.15 Wireless Personal Area Network (WPAN), Bluetooth  Standard IEEE 802.16 Worldwide Interoperability Microwave Access (WiMAX) point to multipoint  Global System for Mobile Communications (GSM) uses GPRS at layer 2 ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 19
  20. 20. Labs  8.5.1- Connecting Devices and Exploring the Physical view (Packet Tracer, connecting devices, verifying connectivity) ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 20

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