L38Xfrev - Review for For Final Exam part C ETHERNET...

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Review for For Final Exam - part C ETHERNET - Physical aspects - Cabling, pulse transmission Range can be increased with repeaters. You don't want two signals sent at the same time, so you could sense a signal from one direction, close a switch. Manchester coding - 1 bit with two pulses.
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802.3 Frame format: Raw bit rate is 10 megabits/second. Fast Ethernet - 100 megabits/second instead of 10 megabits/second. Same frame sizes. Smaller frame durations tend to increase â . Physical alternatives: hub with twisted pair, abandon Manchester coding, use 4 pairs, ternary signaling for 4 bits/baud. Category 5: one wire pair, 125 megabaud, binary pulses, using 4 bits per 5 binary pulses. Optic alternative: pair of optical fibers. One for each direction.
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Gigabit ETHERNET Uses switching, which does away with contention. In one of the modes - full duplex - no channel sensing is needed. Logic Link control (802.2) General link error control that can be associated with any MAC, such as Ethernet. Retransmission (due to errors) and sequence numbering can be provided for in the Link Control (LLC) sublayer. An error detection field (32 bits) is already built into the Ethernet frame. If Internet Transport Protocol TCP/IP is used, acknowledgments are not needed at this link layer level.
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Wireless LANs Physical layer alternatives for 802.11: 1. Infrared 2. Frequency Hopping Spread Spectrum (FHSS) 3. Direct Sequence Spread Spectrum. 4. 802.11a - Orthogonal Freq. Div. Multiplexing (OFDM) in 5 Ghz band. Sending simultaneously on multiple frequencies. 5. 802.11b - High rate Direct Sequence Spread Spectrum. in 2.4 ghz band. 6. 802.11g - OFDM in 2.4 Ghz band. 802.11 recognizes two separate cases: Point coordination function (PCF) - where there is a base station. Uses polling Distributed coordination function (DCF) - where there is no central control. DCF Uses CSMA/CA . CA = Collision Avoidance, RTS, CTS. Bluetooth 802.15 standard. Works with a piconet - a master node and up to 7 slave nodes. Scatternet - a collection of piconets.
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Data link layer switching - Bridges A bridge connects two or more LANS.
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This note was uploaded on 09/23/2009 for the course CMPEN 362 taught by Professor Johnmetzner during the Spring '09 term at Penn State.

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L38Xfrev - Review for For Final Exam part C ETHERNET...

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