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IST 201

IST 201. Chapter 7. Legacy Ethernet. 10Base5 10Base2 10BaseT Common Characteristics Timing parameters Frame format Transmission process Basic design rule. Parameters. Bit time 100 nanoseconds Slot time 512 bit-times Interframe spacing 96 bits Collision attempt limit 16

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IST 201

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Presentation Transcript

  1. IST 201 Chapter 7

  2. Legacy Ethernet • 10Base5 • 10Base2 • 10BaseT • Common Characteristics • Timing parameters • Frame format • Transmission process • Basic design rule

  3. Parameters • Bit time 100 nanoseconds • Slot time 512 bit-times • Interframe spacing 96 bits • Collision attempt limit 16 • Collision back-off limit 10 • Collision jam size 32 bits • Max. frame size 1518 octets • Min. frame size 512 bits/64 octets

  4. Ethernet Frame • Must be between 64 – 1518 bytes #Octets 7 1 6 6 2 46-1500 4 S F D Length Type Preamble Destination Source Data FCS

  5. SQE – Signal Quality Error • Process that occurs @ MAC sub layer • Shows successful outbound frame • When there is a collision • Improper signals • Transmission has been interrupted • Half-duplex – always • Full-duplex - optional

  6. Encoding • Describes how bits are represented by voltages.

  7. Nonreturn to Zero Encoding (NRZ) • 0 = 0 volts • 1 = 5 volts 0

  8. Manchester Encoding • Used in 10 Mbps Ethernet • Direction of the edge transition indicates whether it is a one or zero. • Low to High transition 01 represents 1 • High to Low transition 10 represents 0 • Self-clocking – each bit is transmitted over a predetermined time period Called Biphase code

  9. Shared Ethernet • Share collision domain • Multiple types of media can co-exist • 10BaseT • 10Base2 • 10Base5

  10. Design Rule = 5-4-3 Rule • No more than 5 segments • Separated by no more than 4 repeaters • Coax – no more than 3 segments can have hosts • This rule prevents a 10 Mbps network from having propagation delay problems.

  11. 100 Mbps Ethernet (Fast Ethernet) • 100BaseTx – copper • 100BaseFx – fiber-multimode • Common characteristics • Timing parameters • Frame format • Parts of the transmission process

  12. Timing Parameters 100 Mbps • Bit time 10 nanoseconds • Slot time 512 bit-times • Interframe spacing 96 bits • Collision attempt limit 16 • Collision back-off limit 10 • Collision jam size 32 bits • Max. untagged frame size 1518 octets • Min. frame size 512 bits/64 octets

  13. Fast Ethernet Encoding • Two step process • 4B/5B (4-bit/5 bit) • Encoding specific to media

  14. 4B/5B Encoding • Nibbles (4 bit groupings) are converted to 5-bit symbols. • Control symbols (SFD,FCS) • Data symbols • Necessary to get 10x increase in transmission speed.

  15. Line Encoding - Copper • Multi-level transmit – Level 3 (MLT-3)

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