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  • 1. This module introduces the specifics of the most important varieties of Ethernet.
  • 2.
    • All versions of Ethernet have the same:
      • MAC addressing
      • CSMA/CD
      • Frame format
    • However, other aspects of the MAC sublayer, physical layer, and medium have changed.
    100 802.2 Legacy Ethernet 7.1.1 10-Mbps and 100-Mbps Ethernet
  • 3. 7.1.1 10-Mbps Ethernet Common timing parameters – all 10 Mbps 10BASE2 - 10BASE5 - 10BASE-T
  • 4. 7.1.1 10-Mbps Ethernet Common Frame Format
  • 5. 7.1.1 10-Mbps Ethernet
    • Differences from higher Bit Rates
    • Signal Quality Errors (To tell controller that collision circuitry is functional)
    • SQE is always used in half-duplex. (Can be used in full-duplex operation but is not required.) www.ethermanage.com/ethernet/sqe/sqe.html
    • SQE is active:
      • Within 4 to 8 microseconds following a normal transmission to indicate that the outbound frame was successfully transmitted.
      • Whenever there is a collision on the medium.
      • Whenever there is an improper signal on the medium. Improper signals might include jabber, or reflections that result from a cable short.
      • Whenever a transmission has been interrupted.
    • Encoding – Manchester
    • System Layout (Architecture)
    As the frame passes from the MAC sub-layer to the physical layer, speed dependent processes occur prior to the bits being placed from the physical layer onto the medium.
  • 6. 7.1.1 10-Mbps Ethernet
    • No Direct Current
    • Always a synchronizing signal
    Encoding – Manchester Simple encodings have undesirable timing and electrical Xtics
  • 7.   7.1.2 10BASE5
    • Legacy Ethernet has common architectural features.
    • Networks usually contain multiple types of media.
    • The standard ensures that interoperability is maintained.
    • The overall architectural design is of the utmost importance when implementing a mixed-media network.
    • It becomes easier to violate maximum delay limits as the network grows.
    • The timing limits are based on parameters such as:
      • Cable length and its propagation delay
      • Delay of repeaters
      • Delay of transceivers
      • Inter-frame gap shrinkage
      • Delays within the station
    • The main advantages of 10BASE5 were:
    • It was inexpensive
    • No configuration was necessary
  • 8.
    • Not more than five segments.
    • No more than four repeaters may be connected in series between any two distant stations.
    • No more than three populated segments.
      7.1.2 10BASE5 The 5-4-3 rule. no more than 5 segments separated by more than 4 repeaters, and no more than three populated segments
  • 9. 7.1.3 10BASE2 Thin Net
  • 10. 7.1.4 10BASE-T
  • 11. Signal leaves the NIC and enters the cable on the Orange pair. White- Orange is +ve, solid Orange is negative. Signal leaves the cable and enters the NIC on the SPLIT Green pair. White- Green is +ve, solid Green is negative. 568 B 7.1.4 10BASE-T
  • 12. 7.1.4 10BASE-T
    • UTP is cheaper and easier to install
    • Category 3 and 5 cable are adequate for 10BASE-T networks.
    • New cable installations use Category 5e or better for multiple protocols.
    • 10 Mbps of traffic in half-duplex mode and 20 Mbps in full-duplex mode.
  • 13. 7.1.5 10BASE-T wiring and architecture The 5-4-3 rule still applies.
    • 10BASE-T links can have unrepeated distances up to 100 m.
    • Hubs can solve the distance issue but will allow collisions to propagate.
    • The 100 m distance starts over at a Switch .
  • 14.
    • All versions of Ethernet have the same:
      • MAC addressing
      • CSMA/CD
      • Frame format
    • However, other aspects of the MAC sublayer, physical layer, and medium have changed.
    802.2 Fast Ethernet 7.1 10-Mbps and 100-Mbps Ethernet 100
  • 15. 7.1.6 100-Mbps Ethernet The only difference between Ethernet and Fast Ethernet is the Bit Time The two technologies that have become important are 100BASE-TX, which is a copper UTP medium and 100BASE-FX, which is a multimode optical fiber medium.
  • 16. 7.1.6 100-Mbps Ethernet The 100-Mbps frame format is the same as the 10-Mbps frame.
    • These higher frequency signals are more susceptible to noise.
    • In response to these issues, two separate encoding steps are used by 100-Mbps Ethernet.
      • The first part of the encoding uses a technique called 4B/5B
      • The second part of the encoding is the actual line encoding specific to copper or fiber.
  • 17. 7.1.7 100BASE-TX/FX
    • The data byte to be sent is first broken into two nibbles.
    • If the byte is 0E, the first nibble is 0 and the second nibble is E.
    • Next each nibble is remapped according to the 4B5B table.
      • Hex 0 is remapped to the 4B5B code 11110.
      • Hex E is remapped to the 4B5B code 11100.
    • In 100BASE-FX and 100BASE-TX, the 4B5B replacement happens at the Physical Coding Sub-layer (PCS)
    • Information is then further encoded for transmission using
      • MLT-3 in 100BASE-TX at the Physical Medium Dependent (PMD) sub-layer
      • NRZI in 100BASE-FX at the Physical Media Attachment (PMA) sub-layer
    There will always be at least one ‘1’ in each byte, eliminating long strings of zeros. MULTI-LEVEL TRANSMIT 11101 1111 F 11100 1110 E 11011 1101 D ... ... ... 10100 0010 2 01001 0001 1 11110 0000 0 4B5B Code (Binary) Data (Hex) 4B5B Encoding Table
  • 18. 7.1.7 100BASE-TX multi-level transmit-3 levels 100BASE-TX (like 100BASE-FX) uses 4B/5B encoding which is then scrambled and converted to multi-level transmit-3 levels or MLT-3. Any Transition = binary 1. No transition = binary 0. Long strings of zeros would give a ‘DC’ component but because of the 4B/5B encoding this can never happen.
  • 19. 7.1.7 100BASE-TX
    • 100BASE-TX can be either full-duplex or half-duplex
    • An Ethernet network using separate transmit and receive wire pairs (full-duplex) and a switched topology prevents collisions on the physical bus.
    MLT3 coding
  • 20. 7.1.8 100BASE-FX 100BASE-FX (like 100BASE-TX) uses 4B/5B encoding which is then scrambled and converted to Non Return to Zero, Inverted . Non Return to Zero, Inverted Any Transition = binary 1. No transition = binary 0. Long strings of zeros would give a ‘DC’ component but because of the 4B/5B encoding this can never happen. Fiber cannot use the 3 level MLT3 because the light source has only two levels, ON and OFF.
  • 21. 7.1.8 100BASE-FX 200 Mbps transmission is possible because of the separate Transmit and Receive paths in 100BASE-FX optical fiber.
    • The main application for which 100BASE-FX was designed was inter-building backbone connectivity
    • 100BASE-FX was never adopted successfully. This was due to the timely introduction of Gigabit Ethernet copper and fiber standards.
    • Gigabit Ethernet standards are now the dominant technology for backbone installations, high-speed cross-connects, and general infrastructure needs .
  • 22. 7.1.8 100BASE-FX
  • 23. 7.1.8 100BASE-FX
  • 24. 7.1.9 Fast Ethernet architecture
    • The introduction of switches has made this distance limitation less important.
    • If workstations are located within 100 m of a switch, the 100 m distance starts over at the switch.
    • Since most Fast Ethernet is switched, these are the practical limits between devices.
    A Class I repeater may introduce up to 140 bit-times of latency. Any repeater that changes between one Ethernet implementation and another is a Class I repeater. A Class II repeater may only introduce a maximum of 92 bit-times latency.
  • 25. 7.1.9 Fast Ethernet architecture
    • Only one Class I repeater can be used in a single collision domain.
    • Two Class II repeaters are allowed in a single collision domain, with up to a 5 meter inter-repeater link between them.
    • Class II repeaters are faster than Class I repeaters.
    • This allows Class I repeaters to provide other services besides simple repeating, such as translating between 100BASE-TX and 100BASE-T4.
    • Class II repeaters are primarily used to link two hubs each supporting only a single implementation of Fast Ethernet.
  • 26. Fast Ethernet 7.2.1 1000-Mbps Ethernet Gigabit Ethernet
    • 1000BASE-T inter-switch links are useful for
    • video streaming applications
    • server to DAT backup drive links
    • intra-building backbones
  • 27. Once again the frame remains unchanged.
    • The differences between standard Ethernet, Fast Ethernet and Gigabit Ethernet occur at the physical layer .
    • Since the bits are introduced on the medium for a shorter duration and more often, timing is critical.
    • This high-speed transmission requires frequencies closer to copper medium bandwidth limitations.
    • This causes the bits to be more susceptible to noise on copper media .
    • Like 100Base-TX these issues require Gigabit Ethernet to use two separate encoding steps .
    • Data transmission is made more efficient by using codes to represent the binary bit stream.
    • The encoded data provides synchronization , efficient usage of bandwidth , and improved Signal-to-Noise Ratio characteristics.
    To interconnect a 1000BASE-T network to a 100BASE-T network use a layer 2 bridge or switch.
  • 28. 1 st Frame 2nd Frame 3rd Frame 4th Frame
    • Cat 5e cable can reliably carry up to 125 Mbps of traffic.
    • 1000BASE-T uses all four pairs of wires.
    • This is done using complex circuitry called a Hybrid to allow full duplex transmissions on the same wire pair.
    • This provides 250 Mbps per pair.
    • With all four-wire pairs, this provides the desired 1000 Mbps.
    • Since the information travels simultaneously across the four paths, the circuitry has to divide frames at the transmitter and reassemble them at the receiver.
    Because Gigabit Ethernet is inherently full-duplex, the Media Access Control method views it as a point-to-point link.
  • 29.
    • Fiber cannot do multi level signaling (not 4D-PAM5 nor MLT3)
    • at 1 Gigabit Non Return to Zero (NRZ) signaling is used with
    • 8B/10B coding to ensure that a good synchronizing signal is always present.
  • 30. Examples of 8B/10B coding
    • Features And Operation Of 8B/10B Encoding
    • Every ten bit code group must fit into one of the following three possibilities:
      • Six ones and four zeros
      • Five ones and five zeros
      • Four ones and six zeros
    • This helps limit the number of consecutive ones and zeros between any two code groups.
    flip 110000 0101 001111 1010 101 11100 D28.5 same 001110 1010 001110 1010 101 11100 D28.5 flip 001010 1001 110101 1001 001 00100 D4.1 same 100010 1011 011101 0100 000 00001 D1.0 Effect on RD after Sending RD+ Encoding         Value RD- Encoding         Value Actual Byte    Being Encoded Code     Group Name
  • 31. Different sub layers in the Physical Layer
  • 32. L=Long Wave Length 1300nm S=Short Wave Length 850 nm
    • The Media Access Control method treats the link as point-to-point.
    • Since separate fibers are used for transmitting (Tx) and receiving (Rx) the connection is inherently full duplex.
    • Gigabit Ethernet permits only a single repeater between two stations.
    multimode error 5000 550 550 550 275 100 25
  • 33. Table 1  100BASE-TX, 1000BASE-X, and 1000BASE-T 5 level PAM ANSI FC 8B/10B ANSI FDDI 4B/5B Encoding (PCS) 1000 Mbps 1000 Mbps 100 Mbps Data rate 1.25 Gbaud 125 Mbaud 125 Mbaud Symbol rate 802.3x 802.3x 802.3x Flow control 802.3 Ethernet 802.3 Ethernet 802.3 Ethernet MAC protocol 802.3 Ethernet 802.3 Ethernet 802.3 Ethernet Frame format 1000BASE-T 1000BASE-X 100BASE-TX
  • 34. Fast Ethernet Gigabit Ethernet All versions of Gigabit Ethernet have the same frame format, timing and transmission
  • 35.
    • How does 10GbE compare to other varieties of Ethernet?
    • Frame format is the same, allowing interoperability between all varieties of legacy, fast, gigabit, and 10 Gigabit, with no reframing or protocol conversions.
    • Bit time is now 0.1 nanoseconds. All other time variables scale accordingly.
    • Since only full-duplex fiber connections are used, CSMA/CD is not necessary
    • The IEEE 802.3 sublayers within OSI Layers 1 and 2 are mostly preserved, with a few additions to accommodate 40 km fiber links and interoperability with SONET/SDH technologies.
    • Flexible, efficient, reliable, relatively low cost end-to-end Ethernet networks become possible.
    • TCP/IP can run over LANs, MANs, and WANs with one Layer 2 Transport method.
  • 36.
    • 802.3ae June 2002 10GbE family.
    • 10GBASE-SR – Intended for short distances over already-installed multimode fiber, supports a range between 26 m to 82 m
    • 10GBASE-LX4 – Uses wavelength division multiplexing (WDM), supports 240 m to 300 m over already-installed multimode fiber and 10 km over single-mode fiber
    • 10GBASE-LR and 10GBASE-ER – Support 10 km and 40 km over single-mode fiber
    • 10GBASE-SW, 10GBASE-LW, and 10GBASE-EW – Known collectively as 10GBASE-W are intended to work with OC-192 synchronous transport module (STM) SONET/SDH WAN equipment.
  • 37. Physical Media Dependent Each transceiver has four 3.125-Gbit/s DFB lasers that are optically multiplexed to provide a 10-Gbit/s data throughput. 10GBASE-LX4 uses Wide Wavelength Division Multiplex (WWDM) to multiplex four bit simultaneous bit streams as four wavelengths of light launched into the fiber at one time. Physical Media Attachment
  • 38.  
  • 39. 7.2.7 Future of Ethernet
    • Copper (up to 1000 Mbps, perhaps more)
    • Wireless (approaching 100 Mbps, perhaps more)
    • Optical fiber (currently at 10,000 Mbps and soon to be more)
  • 40. FIN

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