OSI Physical Layer

1. OSI Physical Layer Network Fundamentals – Chapter 8

2. Objectives • Explain the role of Physical layer protocols and services in supporting communication across data networks. • - Describe the role of signals used to represent bits as a frame as the frame is transported across the local media • Describe the purpose of Physical layer signaling and encoding as they are used in networks • Identify the basic characteristics of copper, fiber and wireless network media • Describe common uses of copper, fiber and wireless network media

3. Context Index • 8.1 The Physical Layer – Communication Signals • 8.2 Physical Signaling and Encoding: Representing Bits • 8.3 Physical Media – Connecting Communication • 8.4 Labs – Media Connectors

4. 8.1 The Physical Layer – Communication Signals

5. 8.1.1 Physical Layer - Purpose • The OSI Physical layer provides the means to transport across the network media the bits that make up a Data Link layer frame.

6. 8.1.1 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.

7. 8.1.2 Physical Layer - Operation • There are three basic forms of network media on which data is represented: －Copper cable －Fiber －Wireless

8. 8.1.3 Physical Layer - Standards • Comparison of Physical layer standards and upper layer standards

9. 8.1.3 Physical Layer - Standards • Standards for the Physical layer specify signal, connector, and cabling requirements.

10. 8.1.3 Physical Layer - Standards • Standards for the Physical layer specify signal, connector, and cabling requirements.

11. 8.1.3 Physical Layer - Standards • Standards for the Physical layer specify signal, connector, and cabling requirements.

12. 8.1.3 Physical Layer - Standards • Standards for the Physical layer specify signal, connector, and cabling requirements.

13. 8.1.4 Physical Layer Fundamental Principles • The three fundamental functions of the Physical layer are: －The physical components －Data encoding －Signaling

14. 8.2 Physical Signaling and Encoding: Representing Bits

15. 8.2.1 Signaling Bits for the Media • All communication from the human network becomes binary digits, which are transported individually across the physical media. • Bits are represented on the medium by changing one or more of the following characteristics of a signal: －Amplitude －Frequency －Phase

16. 8.2.1 Signaling Bits for the Media • Method of signaling: －Non Return to Zero (NRZ) Signaling －Manchester Encoding －4B/5B

17. 8.2.2 Encoding – Grouping Bits • One way to provide frame detection is to begin each frame with a pattern of signals representing bits.

18. 8.2.2 Encoding – Grouping Bits • A code group is a consecutive sequence of code bits that are interpreted and mapped as data bit patterns. • Advantages using code groups include: －Reducing bit level error －Limiting energy transmitted －Distinguish data from control －Better media error detection

19. 8.2.3 Data carrying Capacity • Data transfer can be measured in three ways: －Bandwidth －Throughput －Goodput • Bandwidth Digital bandwidth measures the amount of information that can flow from one place to another in a given amount of time.

20. 8.2.3 Data carrying Capacity • Data Throughput and Goodput

21. 8.3 Physical Media – Connecting Communication

22. 8.3.1 Types of Physical Media • Several media characteristics defined by Physical layer standards.

23. 8.3.1 Types of Physical Media • Several media characteristics defined by Physical layer standards.

24. 8.3.2 Copper Media • The types of copper cabling include: －Coaxial cable －Twisted-pair cable · UnshieldedTwisted-pair · ShieldedTwisted-pair

25. 8.3.2 Copper Media • External Signal Interference

26. 8.3.3 Unshielded Twisted Pair (UTP) Cable • The basic characteristics of UTP cable

27. 8.3.3 Unshielded Twisted Pair (UTP) Cable • UTP Cable Types －Ethernet Straight-through －Ethernet Crossover －Rollover

28. 8.3.4 Other Copper Cable • Coaxial cable

29. 8.3.4 Other Copper Cable • Coaxial cable

30. 8.3.4 Other Copper Cable • Shielded Twisted-Pair (STP) Cable

31. 8.3.5 Copper Media Safety • Types of safety issues when working with copper cabling

32. 8.3.6 Fiber Media • Fiber Media Cable Construction

33. 8.3.6 Fiber Media • Fiber Media Cable Construction

34. 8.3.6 Fiber Media • Fiber provides full duplex communications with a cable dedicated to each direction.

35. 8.3.6 Fiber Media • Fiber optic cables can be broadly classified into two types: single-mode and multimode. i

36. 8.2.7 Wireless Media • Wireless media carry electromagnetic signals at radio and microwave frequencies that represent the binary digits of data communications.

37. 8.3.7 Wireless Media • Types of Wireless Networks －Standard IEEE 802.11 －Standard IEEE 802.15 －Standard IEEE 802.16 －Global System for Mobile Communications (GSM)

38. 8.3.7 Wireless Media • The Wireless LAN In general, a wireless LAN requires the following network devices: －Wireless Access Point (AP) －Wireless NIC adapters

39. 8.3.7 Wireless Media • WLAN Ethernet-based standards include: • IEEE 802.11a - Operates in the 5 GHz frequency band and offers speeds of up to 54 Mbps. • IEEE 802.11b - Operates in the 2.4 GHz frequency band and offers speeds of up to 11 Mbps. • IEEE 802.11g - Operates in the 2.4 GHz frequency band and offers speeds of up to 54 Mbps. • IEEE 802.11n - The proposed standard defines frequency of 2.4 GHz or 5 GHz. The typical expected data rates are 100 Mbps to 210 Mbps with a distance range of up to 70 meters.

40. 8.3.8 Media Connectors • Common Copper Media Connectors

41. 8.3.8 Media Connectors • Correct Connector Termination

42. 8.3.8 Media Connectors • Common Optical Fiber Connectors

43. 8.4 Labs – Media Connectors

44. Category 5 UTP Cable Tests • Lab 8.4.1: Media Connectors Lab Activity

45. Summary