Physical Layer (R2)

Physical Layer (R2) - CSCI 232 - Computer Networks Physical...

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CSCI 232 - Computer Networks Physical Layer George Blankenship 1 Physical Layer George Blankenship 1 CSCI 232 Computer Networking: Physical Layer George Blankenship Physical Layer George Blankenship 2 Road Map Physical Desktop System Laptop computer Laser printer Tower System Desktop System Laptop computer IBM RS/60 0 DECstation Modem Modem Fax Telephone Laser printer Desktop System Desktop System IBM S/370 Router Router Transport Network Physical Layer George Blankenship 3 LAN • All devices interconnected by single media • Broadcast environment • Data link layer is device to device • Physical layer is device to device (NIC) Desktop System Laptop computer Laser printer IBM RS/60 0 Fax Laser printer Desktop System Router Data link
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CSCI 232 - Computer Networks Physical Layer George Blankenship 2 Physical Layer George Blankenship 4 WAN • Set of point-to-point links • Non-broadcast environment • Data link layer is device to device • Physical is device to modem (serial port) Modem Modem Device Physical Device Data link Physical Layer George Blankenship 5 Network • Interconnects the locations (networks) • Data link is router to router • Physical is router to modem (serial port) Modem Modem Router Physical Router Data link Physical Layer George Blankenship 6 Lecture Outline • Concepts – Basic concepts and terminology – Signaling – Clocking – Errors • Data encoding • Asynchronous/synchronous clocking • Interfaces
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CSCI 232 - Computer Networks Physical Layer George Blankenship 3 Physical Layer George Blankenship 7 Physical Layer Components • Signaling - voltage levels, optical forms (format of a basic unit of information) • Encoding - message unit definition • Access method - interface with data link Physical Layer George Blankenship 8 Terminology • Bandwidth - frequency of the transmitted signal (Hz) • Data rate - rate that data can be sent (bps) • Noise - average level of noise in the communication path • Error rate - rate that errors occur during transmission Physical Layer George Blankenship 9 Communication Basics • Communication is based upon change • Source generates changes • Destination detects changes • Information is contained in the changes
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This note was uploaded on 09/03/2010 for the course CS 232 taught by Professor Susan during the Summer '09 term at GWU.

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Physical Layer (R2) - CSCI 232 - Computer Networks Physical...

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