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Ethernet Standards. 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 802.3 – Data Link & Medium Access Control DLMAC.
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Ethernet Standards • 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 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 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 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 • Result • Shift in Ethernet shared access – to switched Ethernet • Subsequent – Fast Ethernet – 100BASE-T (1995) • High bit rate interconnectivity requirement • Gigabit Ethernet 109 bits per second • (Ethernet frame format maintained)
Network Connection • Network Interface Card – NIC • Attachment Unit Interface – AUI • Medium Attachment Unit – MAU • PHY + MAC – HW • LLC - SW
Network Connection • MAU – Transceiver • Transmit data • Receive data • Loopback • Collision detection • SQE test • Jabber protection
10BASE5 Thicknet • Early 80s standard • Tapped Bus topology – 50 ohm coax cable • Maximum 500 m segment length • 100/200 users per segment • Max 4 repeaters
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 • 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-FL • Runs over 2 strands of single/multimode fibre • Fibre distance between MAU – 2000m • Point-to-point links
Functions of a NIC • Physical Addressing • Encoding Data • Access to Physical Medium • Connection to Physical Medium • Framing - encapsulate & decapsulate data • Create and Check CRC - error detection • Transceiver - translates signal to medium specific signal
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 • Methods • Static • Configurable • Dynamic
Types of addresses • Broadcast • Multicast • Unicast
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 • 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