IEEE standard

In 1985, the Computer Society of the IEEE started a project, called Project 802, to set standards and to enable inter communication among equipment from a variety of manufacturers.

Project 802 is a way of specifying functions of the physical layer and the data link layer of major LAN protocols.

1. IEEE STANDARDS
Dr R JegadeesanProf & Head
JyothishmathiInstitute of Technology and Science,
karimnagar

2. IEEE STANDARDS
➢In1985,theComputerSocietyoftheIEEE
startedaproject,calledProject802,toset
standardsandtoenableintercommunication
amongequipmentfromavarietyof
manufacturers.
➢Project802isawayofspecifyingfunctions
ofthephysicallayerandthedatalinklayerof
majorLANprotocols.

3. Figuregivesrelationshipof802standardtothetraditionalOSI
model

4. •IEEE 802 standard split data link layer into
two sublayers
•LLC(Logical Link Control) and MAC (Media
Access control)
•In addition to this IEEE 802 created several
physical layer standards for different LAN
protocols
•Ethernet Physical layer
•Token ring Physical layer
•Token bus physical layer

5. LLC(Logical Link Control)
▪In IEEE 802 standard LLC sub layer carries
out Flow control, Error control and Framing.
▪LLC provides one single Data link protocol for
all LANS whereas MAC provides different
protocols for different LANS as shown in
figure.
•The intent of LLC is to provide flow control
and error control for upper layers

6. MAC (Media Access Control)
IEEE802hascreatedasublayercalledMAC
thatdefinesspecificaccessmethodforeach
LAN
forexampleitdefinesCSMA/CDasMedia
accessmethodforEthernetLAN’sandtoken
passingmethodfortokenringandtokenbus
LAN

7. Ethernet
•Asystemforconnectinganumberof
computersystemstoformalocalarea
network,withprotocolstocontrolthepassing
ofinformationandtoavoidsimultaneous
transmissionbytwoormoresystems.

8. Physical layer
•Thephysicallayerisdependentonthe
implementationandtypeofphysicalmedia
used
•IEEEdefinesdetailedspecificationsforeach
LANimplementation

9. Ethernetevolutionthroughfourgenerations

10. Standard Ethernet
•TheoriginalEthernetwascreatedin1976at
Xerox'sPaloAltoResearchCentre(PARC)in
US.
•Sincethen,ithasgonethroughfour
generations:
➢StandardEthernet(10Mbps),
➢FastEthernet(100Mbps),
➢GigabitEthernet(1Gbps),
➢Ten-GigabitEthernet(10Gbps)

11. Physical Layer
•TheStandardEthernetdefinesseveral
physicallayerimplementations;fourofthe
mostcommonare

12. 10Base5: Thick Ethernet
•The first implementation is called 10Base5, thick
Ethernet or Thicknet.
•Thenicknamederivesfromthesizeofthecable,
whichisroughlythesizeofagardenhoseand
toostifftobendwithyourhands.
•10Base5 was the first Ethernet specification to
use a bus topology with an external transceiver
(transmitter/receiver) connected via a tap to a
thick coaxial cable.

13. 10Base5 implementation

14. •The transceiver is responsible for transmitting,
receiving, and detecting collisions.
•The transceiver is connected to the stationvia a
transceiver cablethat provides separate paths for
sending and receiving. This means that collision can
only happen in the coaxial cable.
•The maximum length of the coaxial cable must not
exceed 500 m, otherwise, there is excessive
degradation of the signal.
•If a length of more than 500m, each a maximum of
500-meter can be connected using repeaters

15. 10Base2: Thin Ethernet
•Thesecondimplementationiscalled10Base2,thin
Ethernet,orCheapernet.
•10Base2alsousesabustopology,butthecableis
muchthinnerandmoreflexible.
•In this case, the transceiver is normally part of the
network interface card (NIC), which is installed
inside the station.
•Collisionhereoccursinthethincoaxialcable.

16. NIC(Network Interface Card )

17. 10Base2 implementation

18. •This implementation is more cost effective
than 10Base5 because thin coaxial cable is
less expensive than thick coaxial and the Tee
connections are much cheaper than taps.
•Installation is simpler because the thin
coaxial cable is very flexible. However, the
length of each segment cannot exceed 185 m
(close to 200 m)

19. 10Base-T
•The third implementation is called 10 Base-T
or twisted-pair Ethernet.
•10Base-T uses a physical star topology. The
stations are connected to a hub via two pairs
of twisted cable.
•Notethattwopairsoftwistedcablecreatetwo
paths(oneforsendingandoneforreceiving)
betweenthestationandthehub.Any
collisionherehappensinthehub

20. 10 Base T implementation

21. •Themaximumlengthofthetwistedcable
hereisdefinedas100m,tominimizethe
effectofattenuationinthetwistedcable

22. 10 Base F-Fiber Ethernet
•Themostcommonlyusedopticalfiberis
called10BaseF.
•10Base-Fusesastartopologytoconnect
stationstoahub.
•Thestationsareconnectedtothehubusing
twofiber-opticcables.
•Themaximumlengthoftheopticalcable
hereisdefinedas2000m

23. 10 Base F implementation

25. Addressing in standard Ethernet
•EachstationonanEthernetnetwork(suchas
aPC,workstation,orprinter)hasitsown
networkinterfacecard(NIC).
•TheNICfitsinsidethestationandprovides
thestationwitha6-bytephysicaladdressand
representedinhexadecimalnotationwith
colonbetweenthebytes

26. Example of an Ethernet address in hexadecimal notation

27. •Standard Ethernet address is broadly divided
into 3 types
•Unicast
•Multicast
•Broadcast
•Sourceaddressisalwaysaunicastaddress-
theframecomesfromonlyonestation.
Destinationaddress,however,canbeunicast,
multicast,orbroadcast

28. Unicast:
•Iftheleastsignificantbitofthefirstbyteina
destinationaddressis0,theaddressis
unicast.
•Aunicastdestinationaddressdefinesonly
onerecipient.Therelationshipbetweenthe
senderandthereceiverisone-to-one.

29. Multicast
•If the least significant bit of the first byte in a
destination address is 1, the address is
Multicast.
•A Multicast destination address defines a
group of addresses. The relationship between
the sender and the receiver is one-to-many.

30. Broadcast
•Thebroadcastaddressisaspecialcaseofthe
multicastaddress;therecipientsareallthe
stationsontheLAN.Abroadcastdestination
addressis48bitsandallare1’s.

31. MAC Sub layer
➢InStandardEthernet,theMACsublayer
governstheoperationoftheaccessmethod.
➢Italsoframesdatareceivedfromtheupper
layerandpassesthemtothephysicallayer

32. Frame Format of Standard Ethernet.
802.3 MAC frame

33. •Preamble:Firstfieldofthe802.3frame
contains7bytes(56bits)ofalternating0s
and1s
•Italertsthereceivingsystemtothecoming
frameandenablesittosynchronizeitsinput
timingtohost.
•StartFrameDelimiter(SFD):Thesecond
field(1byte:10101011)signalsthe
beginningoftheframe.

34. •Destination address (DA). The DA field is 6
bytes and contains the physical address of the
destination station or stations to receive the
Frame.
•Sourceaddress(SA).TheSAfieldisalso6
bytesandcontainsthephysicaladdressofthe
senderoftheFrame.
•Lengthortype.Thisfieldisdefinedasatype
fieldorlengthfield.Thisfieldisusedtoknow
numberofbytespresentinthedatafieldin
therangeof0to1500

35. •Data:Thisfieldcarriesactualdataofa
frames.Itisaminimumof46bytesanda
maximumof1500bytes.Iftheframeisless
than46bytesthenthepadfieldisusedtofill
outtheframetotheminimumsize
•CRC(cyclicredundancycheck).Thelastfield
containserrordetectioninformation.

36. Thank you