ETHERNET

1
ETHERNET

• By-
• Pankaj Bisht
• Ashish Patwal
• Rahul
  Dhiman

2
Ethernet (cont..)

• It is a frame based Computer network Technology
  for Local Area Networks.
• This is covered by the IEEE 802.3
• standard that defines what is commonly known
  as the CSMA/CD protocol.

3
Ethernet Overview (contd.)

• Ethernet by definition is a broadcast protocol
• Any signal can be received by all hosts
• Switching enables individual hosts to communicate
• Network layer packets are transmitted over an
  Ethernet by encapsulating
• Frame Format

4
Ethernet (cont..)

• Three data rates are currently
• defined for operation over optical fiber and
  twisted-pair cables
• 10 Mbps10Base-T Ethernet
• 100 MbpsFast Ethernet
• 1000 MbpsGigabit Ethernet
• 10-Gigabit Ethernet is under development.

5
Characterstics ..

• There are other technologies but Ethernet has
  survived as the major LAN technology because its
  protocol has the following characteristics
• Is easy to understand, implement, manage,
  and maintain
• Allows low-cost network implementations
• Provides extensive topological flexibility
  for network
  installation.

6
Our Focus is Ethernet

• History
• Developed by Bob Metcalfe and others at Xerox
  PARC in mid-1970s

7
The CSMA/CD Access Method..

• Carrier Sense Multiple Access / Collision
  Detection, a set of rules determining how network
  devices respond when two devices attempt to use a
  data channel simultaneously (called a collision).
  Standard Ethernet networks use CSMA/CD to
  physically monitor the traffic on the line at
  participating stations. If no transmission is
  taking place at the time, the particular station
  can transmit. If two

8
The CSMA/CD Access Method

• stations attempt to transmit simultaneously,
  this causes a collision, which is detected by all
  participating stations. After a random time
  interval, the stations that collided attempt to
  transmit again. If another collision occurs, the
  time intervals from which the random waiting time
  is selected are increased step by step. This is
  known as exponential back off. CSMA/CD is a type
  of contention protocol.  Networks using the
  CSMA/CD procedure are simple to implement but do
  not have deterministic transmission characteristic

9
Collision Detection.
10
Ethernet Evolution

• 10 Base 5 (Thicknet) (Bus Topology)
• 10 Base 2 (Thinnet) (Bus Topology)
• 10 Base T (UTP) (Star/Tree Topology)
• 10 Base FL (Fiber) (Star/Tree Topology)

11
Ethernet Evolution

• 10BASE5 1983
• 10 Mbps
• 500 meter segment length
• Signal-regenerating repeaters
• Thick Coax
• Advantages Low attenuation, excellent noise
  immunity, superior mechanical strength
• Disadvantages Bulky, difficult to pull,
  transceiver boxes too expensive
• Wiring represented a significant part of total
  installed cost.

12
Ethernet BUS Topology
13
Ethernet Evolution

• 10BASE2 Cheapernet 1985
• 10 Mbps
• 185 meter segment length
• Signal-regenerating repeaters
• Transceiver was integrated onto the adapter
• Thin Coax (coax thinner and lighter)
• Advantages Easier to install, reduced hardware
  cost, BNC connectors widely deployed ? lower
  installation costs.
• Disadvantages Attenuation not as good, could not
  support as many stations due to signal reflection
  caused by BNC Tee Connector.

14
Ethernet Evolution

• 1BASE5 StarLAN 1987
• 1 Mbps
• 250 meter segment length
• Signal-regenerating repeaters
• Transceiver integrated onto the adapter
• Hub-and-Spoke topology (star topology)
• Two pairs of unshielded twisted pair
• Advantages Since four or more UTP are ubiquitous
  in buildings, it is easier to use installed
  wiring in the walls. Telephone wiring is
  hierarchical ? can use wiring closets.

15
Ethernet Evolution

• 10BASET 1990 Most popular
• 10 Mbps
• 100 meter segment length
• Signal-regenerating repeaters
• Transceiver integrated onto adapter
• Two pairs of UTP
• Hub-and-spoke topology Hub in the closet
• Advantages could be done without pulling new
  wires. Each hub amplifies and restores incoming
  signal.

16
Ethernet STAR Topology
17
Open system interconnection

• International Standard Organisation (ISO) has
  proposed Open System Interconnection(OSI)
  reference model which provides a framework of
  data communication protocols.OSI model addresses
  the problem of interconnection of different
  computer and associated devices.

18
Open System Interconnection Model
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
Physical

Network
Data Link
Physical
Network
Data Link
Physical
19
OSI Layers

• PhysicalTo send the data bit stream over
  Communication network.
• Data LinkTo recover from Transmission error.
• NetworkConcerned with routing and congestion
  control.
• TransportTo receive the data from session layer
  and divide it into pieces to pass it to network
  layer.

20
OSI Layers (contd..)

• SessionEstablishes a session for communication
  between two hosts.
• PresentationServes as an interface between
  Application and Communication network.
• ApplicationTo provide the facility to use the
  other layer.

21
Advancement.

• A newer version of Ethernet, called 100Base-T
  (or Fast Ethernet), supports data transfer rates
  of 100 Mbps. And the newest version, Gigabit
  Ethernet supports data rates of 1 gigabit (1,000
  megabits) per second.