chap8 - Physical Layer Network Fundamentals Chapter 8...

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© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public ITE I Chapter 6 1 Physical Layer Network Fundamentals – Chapter 8 Modified by Tony Chen 05/20/2008
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© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public ITE 1 Chapter 6 2 Notes: If you see any mistake on my PowerPoint slides or if you have any questions about the materials, please feel free to email me at chento@cod.edu . Thanks! Tony Chen College of DuPage Cisco Networking Academy
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© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public ITE 1 Chapter 6 3 Objectives In this chapter, you will learn to: Explain the role of Physical layer protocols and services in supporting communication across data networks. Describe the purpose of Physical layer signaling and encoding as they are used in networks. Describe the role of signals used to represent bits as a frame is transported across the local media. Identify the basic characteristics of copper, fiber, and wireless network media. Describe common uses of copper, fiber, and wireless network media.
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© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public ITE 1 Chapter 6 4 Physical Layer - Purpose The OSI Physical layer layer accepts a complete frame from the Data Link layer and encodes it as a series of signals that are transmitted onto the local media. The delivery of frames across the local media requires the following Physical layer elements: –The physical media and associated connectors –A representation of bits on the media –Encoding of data and control information –Transmitter and receiver circuitry on the network devices At this stage of the communication process, –The user data has been segmented by the Transport layer, –Placed into packets by the Network layer –Further encapsulated as frames by the Data Link layer. –The purpose of Physical layer is to create the electrical, optical, or microwave signal that represents the bits in each frame. –These signals are then sent on the media one at a time. It is also the job of the Physical layer to retrieve these individual signals from the media, restore them to their bit representations, and pass the bits up to the Data Link layer as a complete frame.
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© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public ITE 1 Chapter 6 5 Physical Layer - Operation The media does not carry the frame as a single entity. The media carries signals, one at a time, to represent the bits that make up the frame. There are 3 basic forms of network media: –Copper cable •For copper cable media, the signals are patterns of electrical pulses. –Fiber •For fiber, the signals are patterns of light. –Wireless •For wireless media, the signals are patterns of radio transmissions. When the Physical layer encodes the bits into the signals for a
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chap8 - Physical Layer Network Fundamentals Chapter 8...

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