wired Lans ethernet in routing and switching

routing and switching

1. Chapter 13
Wired LANs: Ethernet
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2. Chapter 5: Outline
13.1ETHERNETPROTOCOL
13.2STANDARDETHERNET
13.3FASTETHERNET
13.4GIGABITETHERNET
13.510GIGABITETHERNET

3. 13.3
13-1 ETHERNET PROTOCOL
Thedata-linklayerandthephysical
layeraretheterritoryofthelocaland
wideareanetworks.Thismeansthat
whenwediscussthesetwolayers,we
aretalkingaboutnetworksthatare
usingthem.

4. 13.4
13.13.1 IEEE Project 802
In1985,theComputerSocietyoftheIEEEstarteda
project,calledProject802,tosetstandardstoenable
intercommunicationamongequipmentfroma
varietyofmanufacturers.Project802doesnotseek
toreplaceanypartoftheOSImodelorTCP/IP
protocolsuite.Instead,itisawayofspecifying
functionsofthephysicallayerandthedata-link
layerofmajorLANprotocols.Therelationshipof
the802StandardtotheTCP/IPprotocolsuiteis
showninFigure13.13.

5. 13.13.1 IEEE Project 802
IEEE divided the Data link layer into two
sublayer:
upper layer : logical link control (LLC);
flow and error control.
Lower sublayer: Multiple access (MAC);
media access control.
Multiple access (MAC) :for resolving
access to the shared media.
If channel is dedicated ( point to point)
we do not need the (MAC); sublayer.

6. 13.6
Figure 13.1: IEEE standard for LANs

7. LLC (Logical link control)and MAC (Media Access
Control)
In IEEE project 802, flow control , error control, and
part of the framing duties are collected into one
sublayercalled the logical link control (LLC )
LLC provides one single data link control for all
IEEE LANs.
IEEE project 802 has created a sublayerMACthat
defines the specific access method for each LAN. In
contrast to the LLC, MAC contains a number of
distinct modules: each defines the access method
and the framing format specific to the
corresponding LAN protocol
For example:
•CSMA/CD as media access method for Ethernet
LANs.
•Token passing method for Token Ring and Token
Bus LANs

8. ETHERNET Evolution

9. 13.9
Figure 13.2 : Ethernet evolution

10. 13.10
13-2 STANDARD ETHERNET
WerefertotheoriginalEthernet
technologywiththedatarateof10Mbps
astheStandardEthernet.Althoughmost
implementationshavemovedtoother
technologiesintheEthernetevolution,
therearesomefeaturesoftheStandard
Ethernetthathavenotchangedduring
theevolution.Wediscussthisstandard
versionfirst.

11. 13.11
13.2.1 Characteristics
LetusfirstdiscusssomecharacteristicsoftheStandard
Ethernet.
•Connectionlessandunreliableservice
•Frameformat:
•Frame length:
•Minimum:64bytes(512bits)
•Maximum:1518bytes(12,144bits)

12. 13.12
Frame format
The Ethernet frame contains seven fields:
•Preamble: 7bytes (56 bits); Alternating 0s and 1s,
used for synchronizing
•Start Frame Delimiter (SFD): 10101011 indicates the
start of the frame. Last two bits (11) alerts that the
next field is destination address.
•preamble and SFD are added at the physical layer and
is not formally part of the frame
•Destination Address (DA): Destination address
•Source Address (SA): Source Address
•Type: Define the upper-layer protocol using the MAC
frame. OR define the number of bytes in the data
filed.
•Data: minumum: 46 and maximum : 1500 bytes
•CRC:error detection information:CRC-32

13. 13.13
Figure 13.3: Ethernet frame
•Minimum data length: 46 bytes
•Maximum data length : 1500 bytes

14. Showhowtheaddress47:20:1B:2E:08:EEissentout
online.
Solution
Theaddressissentlefttoright,bytebybyte;foreachbyte,
itissentrighttoleft,bitbybit,asshownbelow:
Example 13.1
13.14

15. 13.15
13.2.2 Addressing
EachstationonanEthernetnetwork(suchasaPC,
workstation,orprinter)hasitsownnetwork
interfacecard(NIC).TheNICfitsinsidethestation
andprovidesthestationwithalink-layeraddress.
TheEthernetaddressis6bytes(48bits),normally
writteninhexadecimalnotation,withacolon
betweenthebytes.Forexample,thefollowingshows
anEthernetMACaddress:

16. 13.16
Figure 13.4: Unicast and multicast addresses
•Source address is always a unicast address –the
frames comes from only one station.
•Destination address can be:
•unicast: defines only one recipient; one to one
•multicast: a group of addresses; one to many
•Broadcast: the recipients are all the stations on the
LAN

17. Definethetypeofthefollowingdestinationaddresses:
a.4A:30:10:21:10:1A
b.47:20:1B:2E:08:EE
c.FF:FF:FF:FF:FF:FF
Example 13.2
Solution
Tofindthetypeoftheaddress,weneedtolookatthe
secondhexadecimaldigitfromtheleft.Ifitiseven,the
addressisunicast.Ifitisodd,theaddressismulticast.Ifall
digitsareFs,theaddressisbroadcast.Therefore,wehave
thefollowing:
13.17

18. Example 13.2 (continued)
a.ThisisaunicastaddressbecauseAinbinaryis1010
(even).
b.Thisisamulticastaddressbecause7inbinaryis0111
(odd).
c.ThisisabroadcastaddressbecausealldigitsareFsin
hexadecimal.
13.18