Ethernet Standards

1
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

2
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

3
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

4
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

5
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)

6
Network Connection

• Network Interface Card NIC
• Attachment Unit Interface AUI
• Medium Attachment Unit MAU
• PHY MAC HW
• LLC - SW

7
Network Connection

• MAU Transceiver
• Transmit data
• Receive data
• Loopback
• Collision detection
• SQE test
• Jabber protection

8
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

9
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

10
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

11
10BASE-FL

• Runs over 2 strands of single/multimode fibre
• Fibre distance between MAU 2000m
• Point-to-point links

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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

13
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

14
MAC addressing

• Methods
• Static
• Configurable
• Dynamic

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Types of addresses

• Broadcast
• Multicast
• Unicast

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Ethernet Frame Format
17
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

18
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