Ethernet Technology

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Module Ethernet Technology
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Ethernet - the History

• 1973 Development begins
• 1976 First paper on Ethernet published
• 1977 Ethernet is patented
• 1979 DEC, INTEL, and XEROX collaborate on
  Ethernet Version 1.
• 1980 Ethernet V.1 is published
• 1980 Xerox ships first Ethernet
• 1982 Ethernet version 2 is published
• 1983 IEEE approves 802.3 standard
• 1985 Ethernet is produces by more than 200
  vendors
• 1985 Installed base exceeds 20.000 Units
• 1992-1994 Fast Ethernet / 100 Mbps/ Switching

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IEEE 802.3 standards
10BASE-2 10BASE-5 10BASE-T 10BASE-F
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Ethernet Access Method

• CSMA/CD
• Carrier Sense
• Listen before trying to transmit - is the cable
  free?
• Multiple Access
  
• Many Stations are allowed to use the same
  media
• Collision Detect
• Be aware of signal collisions - back off when
  detected

Signal
Collision
Signal
50 ohm Terminator
50 ohm Terminator
Shared media ( bus )
Computer earth
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Ethernet Frames
MAC addresses
IEEE 802.3
FCS (4 bytes)
Preample 1010....10 (56 bits)
SFD 10....11 (8 bits)
DA (6 bytes)
Length (2 bytes)
Data . . . . .
(padding)
SA (6 bytes)
(45 - 1500 bytes)
MAC addresses
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Ethernet Transceiver

• Physical Signalling
• Collision Detect
• SQE Test
• Jabber Function

LAN media
Transceiver
Power
Collision
RX Wires
TX Wires
Drop cable to station (AUI Interface)
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10BASE-5 Yellow Cable

• Max. 500 m. Cable Segments
• Max. 100 Stations per Cable Segment
• 2.5 m. between Transceivers
• 50 Ohm terminator at each end

2.5 m.
Transceiver
50 ohm Terminator
50 ohm Terminator
(IEEE802.3 media)
Drop cable
Computer earth
AUI interface
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10BASE-2 Cheapernet Cable

• Max. 185 m. Cable Segments
• Max. 30 Stations per Cable Segment
• Min. 0.5 m. Distance between Stations
• BNC Connectors used to attach stations
• 50 Ohm terminator at each end

50 ohm Terminator
External transceiver Drop cable AUI interface
BNC T Connector Build-in transceiver
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10BASE-T UTP Cable

• Requires a Cabling Hub
• Max. 100 m. from Station to Hub

Cabling Hub (repeater)
Star topology
100 m. Cable segments
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10BASE-F Fiber Optic Cable

• Noise Immune
• No Ground Loops
• Long Distance (up to 2Km.)
• Stations connect to a Central Hub
• Max. Two Stations per Cable Segment
• Typically used for Inter-Hub Connectivity

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Intelligent structured wiring systems

• Increased Flexibility
• Improved Availability
• Inherent Management Capabilities

Cabling Hub
Patch panel
Cabling conducts
Port status - active - not active
- partitioned
Network Management - control - monitoring
RJ-45 outlets
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10BASE-TF Design Rules
1
2
1
Link segments
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10BASE-T Max. 100 m.
10BASE-T Max. 100 m.
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3
4
10BASE-F Max. 1000 m.
10BASE-F Max. 500 m.
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5
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Ethernet Transparent Bridges

• Bridges Receive and Buffer the Frames
• Each Side of a Bridge is a Separate Collision
  Domain
• Bridges Decide to Discard or Forward Packets
• Bridges allow for a more Effective Utilization of
  the Overall Bandwidth

Dedicated 10 Mbps
Collision Domain
Collision Domain
Dedicated 10 Mbps
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Fast Ethernet

• 100 Mbps
• 100BASE-T
• or
• 100VG-AnyLAN

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Switched Ethernet
Full duplex 10Mbps
100BASE-T
Replaces the old Hub
Ethernet Switch
Existing cabling and adapters
Shared 10Mbps segment
Dedicated 10Mbps segments
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