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Ethernet Standards. Ethernet concepts origin DIX consortium – 1979 10Mbps Ethernet 1 st Blue book – 1980 IEEE group takes over – Project 802 802.1 – High Level Interface –HLI – Focused on high level inter-network protocols & management 802.2 – Logic Link Control

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Ethernet standards
Ethernet Standards

  • Ethernet concepts origin

  • DIX consortium – 1979

  • 10Mbps Ethernet 1st Blue book – 1980

  • IEEE group takes over – Project 802

    • 802.1 – High Level Interface –HLI –

      • Focused on high level inter-network protocols & management

    • 802.2 – Logic Link Control

    • 802.3 – Data Link & Medium Access Control

      • DLMAC


Ethernet standards1
Ethernet Standards

  • 1982 – DLMAC – 3 groups

    • 802.3 – CSMA/CD – driven by DIX

    • 802.4 – Token Bus – burroughs, concorde,

    • 802.5 – Token – Ring - IBM

  • 1982 – DIX & IEEE merges

    • 1st version of 802.3 Ethernet standard


Ethernet standards2
Ethernet Standards

  • IEEE 802.3 – series of specifications for 10Mbps

    • Thick coaxial – thicknet – 10Base5

    • Thin coaxial – thinnet- cheapernet –10Base2

    • UTP XBaseT

    • Fibre XBaseF

    • Broadband version XBroad36


Ethernet standards3
Ethernet Standards

  • Other specifications

    • 100 Mbs – fast Ethernet

    • 1000 Mbps – gigabit Ethernet

    • Switched Ethernet

    • Proposal for 100MBps – 1982

    • IEEE 802 focused on 1- 20 MBps

    • ANSI took up 100 Mbps - led to FDDI


Ethernet popularity
Ethernet Popularity

  • Low network management requirements

  • Open standards

    • Reasonable prices

    • Easy to license

    • 1990 – 10Mpbs Ethernet on UTP

      • 10BASE-T – inexpensive twisted pair

      • Massive surge in Ethernet installations


Ethernet popularity1
Ethernet Popularity

  • Coincides with distributed high-performance computing to the desktop

  • Result

    • Large networks – many systems

    • More network aware applications

    • Massive increase in BW needs


  • Ethernet popularity2
    Ethernet Popularity

    • Result

      • Need for higher bit rates – fast Ethernet (1995 – 100BaseT)

      • Shift in Ethernet shared access – to switched Ethernet

      • High bit rate interconnectivity requirement

        • Gigabit Ethernet 109 bits per second

      • (Ethernet frame format maintained)



    Network connection
    Network Connection

    • Network Interface Card – NIC

    • Attachment Unit Interface – AUI

    • Medium Attachment Unit – MAU

    • PHY + MAC – HW

    • LLC - SW


    Network connection1
    Network Connection

    • PLS resides in DTE

      • Data o/p

      • Data I/p

      • Carries Sense

      • Error Sense

    • MAC

      • Data output in NRZ format


    Network connection2
    Network Connection

    • MAC

      • Data output in NRZ format

    • PLS Manchester encoding – differential

    • AUI cable – 3 different signal pairs

      • DO

      • DI

      • CI (control input)


    Network connection3
    Network Connection

    • AUI cable – 3 different signal pairs

      • Max length 50m

      • 15 pin connectors

      • Female on the DTE side

      • Male on the MAU side


    Network connection4
    Network Connection

    • MAU – Transceiver

      • Transmit data

      • Receive data

      • Loopback

      • Collision detection

      • SQE test

      • Jabber protection


    Bus technologies
    Bus Technologies

    • 10BASE5 – Thicknet – coaxial

    • 10BASE2 – Thinnet, coaxial – cheapernet

    • 10BASE-T – Twisted Pair


    10base5 thicknet
    10BASE5 Thicknet

    • Early 80s standard

    • Tapped Bus topology – 50 ohm coax cable

    • Maximum 500 m segment length

    • 100 users per segment

    • Max 4 repeaters


    10base5 thicknet1
    10BASE5 Thicknet

    • Transceivers separated by 2.5m

    • AUI- NIC to transceiver max 50 m



    10base2 thinnet
    10BASE2 Thinnet

    • 1989 standard BNC ( British Navel Connector)

    • Less expensive cable – flexible – to the desktop

    • Max segment size 185m, max nodes 30

    • Max length with repeaters – 925 m

    • Min distance between MAU = 0.5m


    10base t twisted pair
    10BASE-T Twisted Pair

    • Uses standard voice grade telephone cable

    • 1990 – IEEE 802.3i UTP standard

    • 4 twisted pairs

    • Star topology – logically bus

    • Hub – repeater at the centre

      • Signal restoration

      • Repeated incoming signal in all output ports


    10base t twisted pair1
    10BASE-T Twisted Pair

    • Advantages of star

    • Cable distance 100m to repeater

    • MAUs can be connected via AUI

    • MAU & AUI can be part of DTE or repeater


    10base fl
    10BASE-FL

    • Runs over 2 strands of single/multimode fibre

    • Fibre distance between MAU – 2000m

    • Point-to-point links


    Functions of a nic
    Functions of a NIC

    • Create and Check CRC - error detection

    • Physical Addressing

    • Medium Access

    • Framing - encapsulate & decapsulate data

    • Encoding Data

    • Connection to Physical Medium

    • Transceiver - translates signal to medium specific signal


    Physical mac addresses
    Physical MAC addresses

    • Unique Addresses

    • assigned by the IEEE

    • 48 bit address in two parts

      • First 24 bits specify the vendor (block number)

        • ex. AA-00-00 is a DEC NIC board

        • ex. 08-20-00 is SUN

      • Next 24 bits are a unique serial number


    Mac addressing
    MAC addressing

    • Static

      • Most common

      • Vendor guaranteed uniqueness

    • Configurable

      • SW assigned MAC address

    • Dynamic

      • Random pick and check for uniqueness


    Types of addresses
    Types of addresses

    • Broadcast

    • Multicast

    • Unicast


    Broadcast addresses
    Broadcast addresses

    • A MAC address of all one’s

    • All NIC’s on a network accept broadcast addressed messages


    Multicast addresses
    Multicast addresses

    • A specific MAC address that only certain NIC are programmed to accept

      • the first bit of the destination address is set to 1


    Unicast addresses
    Unicast addresses

    • A unique MAC address assigned to each NIC which is used to send messages to that specific host.

      • the first bit of the destination address is set to 0



    Ethernet operation
    Ethernet Operation

    • Broadcast/half duplex network

      • On a bus topology

    • Listen first then transmit if clear

    • What to do if you collide

      • Backoff and try again


    Csma cd
    CSMA/CD

    • LAN transmissions operate on the idea of a bit period

    • For 10baseT this is 100ns (10,000,000 bits/sec)

    • 3 times to keep track of

      • Slot time

      • Interframe gap

      • Jam period


    Timings
    Timings

    • Slot time – min time transmitter needs to access media to transmit smallest frame

      • All nodes must listen for 1 slot time before transmitting

      • 512 bit periods or 51.2 µsec

    • Interframe Gap (dead time) – space between transmissions of 96 bit periods or 9.6 µsec


    Timings1
    Timings

    • On collision

    • All stations involved stop transmitting and transmit 32 bit time (3.2 µsec) jam signal

    • All attached stations hear the jam signal

    • Back-off algorithm used to determine when another attempt will be made

      • This is done up to 16 times


    Ethernet operations
    Ethernet Operations

    • Min frame size: 64 bytes (72 counting preamble and SFD)

    • 64 bytes incl CRC, control, addresses and data fields (64 x 8 x 100ns = 51.2 µsec)

    • Max size is 1526 bytes