describes about the Ethernet, its working and types.

1. IEEE 802.3

2. ETHERNET
• Family of computer networking technologies for LANs &
MANs.
• It was introduced in 1980 & standardised in 1982 as IEEE
802.3.
• It supports higher bitrates & longer link distances.

3. WORKING
• Ethernet system works off of the CSMA/CD standard.
• CSMA/CD- The computers that have access to the transmission
medium can send and receive data.
• Benefit- ability to sense collisions.

4. DATA FRAME
• Ethernet system sends information through the network using MAC
Data frames.
• Data frame – Small slice of data wrapped on MAC information.

5. PREAMBLE
• It tells the receiving node that a data frame is coming.
• 56 bits (7 bytes).
START FRAME DELIMITER ( SFD)
• Signals the beginning of the frame.
• 1 byte: 10101011
DESTINATION ADDRESS ( DA)
• Contains the physical address of the destination to receive the packet.
• 6 byte
• Types:-
Destination Address
Unicast Multicast Broadcast

6. SOURCE ADDRESS
• Physical address of the sender.
• 6 bytes.
• Always unicast.
LENGTH
• Total no: of bits of information contained in the data frame.
DATA
• The actual data.
• Length of the data must be between 46-1500 bytes.
FRAME CHECK SEQUENCE ( FCS)
• Contains error detection information.
• 32 bits CRC value.

7. TYPES OF ETHERNET
• 3 versions.
• The difference between these types lies in the speed at which they
can transmit data.

8. STANDARD ETHERNET
• It can transmit data at 10 Mbps.
• CSMA/CD is used to access network.
• The media are shared between all stations.
PHYSICAL LAYER
Physical Layer
Signalling (PLS)
Medium Attachment
Unit ( MAU)
Medium
Attachment Unit Interface
(AUI)
Medium-Dependent
Interface (MDI)

9. PHYSICAL LAYER SIGNALLING (PLS)
• It encodes and decodes the data using Manchester.
ATTATCHMENT UNIT INTERFACE ( AUI)
• It defines the interface between PLS & MAU.
• It uses thick coaxial cable.
MEDIUM ATTATCHMENT UNIT (MAU)
• Transceiver.
• Medium dependent.

10. PHYSICAL LAYER IMPLEMENTATION

11. 10Base5: Thick Ethernet
• 10Base5 is called as Thick Ethernet or Thicknet; Uses coaxial cable.
• Uses Bus topology.

12. 10Base2: Thin Ethernet
• Thin Ethernet or Cheapernet.
• Uses Bus topology

13. 10Base-T: Twisted pair Ethernet
• Twisted-pair Ethernet.
• Physical star topology

14. 10Base-F: Fiber link Ethernet
• Fiber Link Ethernet.
• Uses star topology to connect stations to a hub

15. SUMMARY
NAME CABLE MAX. SEG NODES/SEG ADVANTAGES
10BASE5 Thick coaxial cable 500 m 100
Original cable
No obsolete
10BASE2 Thin coaxial cable 185 m 30
No hub needed
10BASET Twisted pair 100 m 1024
Cheapest system
10BASE F Fiber optics 2000 m 1024
Best between
buildings

16. CHANGES IN THE STANDARD
1. Bridged Ethernet
• Without bridges , all the stations share the bandwidth of the network.
• Bridges have 2 effects on ethernet :
i. They raise the bandwidth
ii. Separate collision domains

17. Separating collision domain:

18. 2. Switched Ethernet
• Switch is an N –port bridge with additional sophistication that allows
faster handling of the packets.

19. 3. Full Duplex Ethernet
• Full duplex mode increases the capacity of each domain from 10-20Mbps.
• Instead of using one link between station and switch, uses two links: one to
transmit and one to receive.
• No need for CSMA/CD.

20. FAST ETHERNET
• IEEE 802.3u.
• 100 Mbps.
• CSMA/CD.
• Backward compatible.
• Auto negotiation : It allows two devices to negotiate the mode or data rate
of operation.

21. PHYSICAL LAYER
• It is made up of 4 sub layers: RS, MII, PHY, MDI.
RECONCILIATION
(RS)
JFEPHYSICAL LAYER ENTITY
(PHY)
MEDIUM
Medium-Independent Interface
(MII)
Medium-Dependent Interface
(MDI)

22. RECONCILIATION(RS)
• RS replaces the PLS sub layer in the traditional Ethernet.
• Responsible for passing data to the MII.
 MEDIUM INDEPENDENT INTERFACE(MII)
• AUI replaced with MII.
• Backward compatible with AUI.
 PHYSICAL LAYER ENTITY(PHY)
• Transceiver.
• Responsible for encoding and decoding.
 MEDIUM DEPENDENT INTERFACE(MDI)
It connects transceiver to the medium

23. PHYSICAL LAYER IMPLEMENTATION
• Two wire or four wire:
— Two wire: 100Base-X: With twisted pair (100Base-TX) or Fiber
optic (100Base-FX).
— Four wire: Twisted pair (100BaseT4).

24. SUMMARY
CHARACTERISTICS 100BASE-TX 100BASE- FX 100BASE-T4
MEDIA CAT 5 UTP/STP FIBER 4 UTP
NO: OF WIRES 2 2 4
MAX IMUM
LENGTH
100 m 100 m 100 m

25. GIGA BIT ETHERNET
• IEEE 802.3Z.
• 1000 Mbps.
• CSMA/CD.
PHYSICAL LAYER
• Physical layer is made up of 4 sub layers:
o RS
o GMII
o PHY
o MDI

26. Reconciliation
(RS)
Gigabit Medium – Independent
Interface
(GMII)
Physical Layer Entity (PHY)
Medium
Medium – Dependent Interface (MDI)

27. RECONCILIATION (RS)
• Sends 8 bit data to PHY via GMII interface.
GIGABIT MEDIUM-INTERFACE (GMII)
• Connects RS sub layer to the PHY sub layer.
• It is a logical interface.
PHYSICAL LAYER ENTITY(PHY)
• Encodes and decodes the data.
MEDIUM-DEPENDENT INTERFACE
• Connects the transceiver medium.

28. PHYSICAL LAYER IMPLEMENTATION
• 1000Base-X: Two wire implementation
• Short wave optical fiber (1000Base-SX)
• Long wave optical fiber (1000Base-LX)
• Short copper jumpers (1000Base-CX) using STP.
• 1000Base-T: Four-wire version using twisted-pair cable [UTP].

29. SUMMARY
CHARACTERISTSICS 1000BASE-SX 1000BASE-
LX
1000BASE-CX 1000BASE-T
MEDIA FIBER FIBER STP UTP
NO: OF WIRES 2 2 2 4
MAXIMUM LENGTH 550m 5000m 25m 100m