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CCNACisco Certified Network Associate
640-802
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Mohammedsn
علما ” ” زدني رب قل و تعالي قال
OSI 7 layerOSI 7 layerOSI Open System InterconnectionOSI Open System InterconnectionWe want the system to be standard to can We want the system to be standard to can
any one use itany one use it ISO International Standard Organization ISO International Standard Organization Make standarization to main task for Make standarization to main task for
operation ( IEEE)operation ( IEEE)
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33
OSI Model OverviewOSI Model Overview
Data Flow Layers
Transport Layer
Data Link
Network Layer
Physical
Application (Upper) Layers
Session
Presentation
Application
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7- Application 7- Application LayerLayer
HTTP : Browsing protocolHTTP : Browsing protocolFTP : File Transfer Protocol FTP : File Transfer Protocol TFTP : Trivial FTPTFTP : Trivial FTPTelnet : Remote access protocolTelnet : Remote access protocolSMTP : Simple Mail Transfer protocol SMTP : Simple Mail Transfer protocol SNMP : Simple Network Management SNMP : Simple Network Management
ProtocolProtocol
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66 - -presentation layerpresentation layer
Format of data Format of data Compression & decompression of dataCompression & decompression of dataEncoding & decoding of data Encoding & decoding of data
Such ac ASCII code ( 8bit) , EBCDIC code Such ac ASCII code ( 8bit) , EBCDIC code (5bit) (5bit)
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55 - -session layersession layer Set a logical connection ( session) Set a logical connection ( session)
between different applicationbetween different applicationSpecifies communication mode Specifies communication mode ( simple - Half duplex – full duplex ) ( simple - Half duplex – full duplex )
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44 - -Transport layerTransport layer
Flow control Flow control
Error recovery Error recovery
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Flow controlFlow control
Pc1 Pc2
stop
Go on
BufferingCongestion avoidence
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WindowingWindowing
Sender Receiver
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WindowingWindowing
Window size = 3Send 2
Sender ReceiverWindow size = 3Send 1
Window size = 3Send 3
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Window size = 3Send 2
WindowingWindowing
Sender Window size = 3Send 1
Window size = 3Send 3
ACK 3Window size = 2
Packet 3 isDropped
Receiver
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Window size = 3Send 2
WindowingWindowing
Sender Window size = 3Send 1
Window size = 3Send 3
ACK 3Window size = 2
Packet 3 isDropped
Window size = 3Send 4
Window size = 3Send 3
Receiver
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Window size = 3Send 2
WindowingWindowing
Sender Window size = 3Send 1
Window size = 3Send 3
ACK 3Window size = 2
Packet 3 isDropped
Window size = 3Send 4
Window size = 3Send 3
ACK 5Window size = 2
Receiver
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TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment NumbersSource
PortDest.Port
…Sequence#
Acknowledgement#
Source Dest. Seq. Ack.1028 23 10 1
I justsent #10.
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TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment Numbers
I just got #10,now I need #11.
SourcePort
Dest.Port …Sequence
#Acknowledgement
#
1028 23
Source Dest.
1010
Seq.
1
Ack.
102823
Source Dest.
1111
Seq.
1
Ack.
I justsent #10.
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TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment NumbersSource
PortDest.Port …Sequence
#Acknowledgement
#
1028 23
Source Dest.
1111
Seq.
2
Ack.
1028 23
Source Dest.
1010
Seq.
1
Ack.
102823
Source Dest.
1111
Seq.
1
Ack.
I just got #10,now I need #11.
I justsent #11.
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Mohammedsn
TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment NumbersSource
PortDest.Port …Sequence
#Acknowledgement
#
1028 23
Source Dest.
1111
Seq.
2
Ack.
1028 23
Source Dest.
1010
Seq.
1
Ack.
102823
Source Dest.
1111
Seq.
1
Ack.
102823
Source Dest.
1212
Seq.
2
Ack.
I just got #11,now I need #12
I justsent #11.
Type of protocol at transport layerType of protocol at transport layer
TCP (connection oriented protocol)TCP (connection oriented protocol)
It must establish session before transmit the It must establish session before transmit the data , make recovery&controldata , make recovery&control
UDP connectionless protocol no UDP connectionless protocol no session,no recovery&no control session,no recovery&no control
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3-Network layer
1-routing 2-IP addressing
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22 - -Data linkData link 1- Arbitration : find the best time to send 1- Arbitration : find the best time to send
the data ( CSMA/CD & taken) the data ( CSMA/CD & taken)
Error detection Error detection 1- parity check : but very week1- parity check : but very week2-CRC : Depend on mathematical equation 2-CRC : Depend on mathematical equation
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Data link is divided into two sub Data link is divided into two sub layerlayer
802.3 MAC sub layer ( Media Access 802.3 MAC sub layer ( Media Access control) control)
802.2 LLC sub layer ( Logical Link Control) 802.2 LLC sub layer ( Logical Link Control)
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MAC address : hardware address
48 bit
24 bit ( vendor) 24 bit IEEE
LLC sub layerLLC sub layer
TCP/IP SPX/IPX
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Physical Layer: Physical Layer: Ethernet/802.3Ethernet/802.3
Hub
Hosts
Host
10Base2—Thin Ethernet10Base5—Thick Ethernet
10BaseT—Twisted Pair
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Encapsulating Data
Transport
Data Link
Physical
Network
Upper Layer Data
Upper Layer DataTCP Header
DataIP Header
DataLLC Header
0101110101001000010
DataMAC Header
Presentation
Application
Session
Segment
Packet
Bits
Frame
PDU
FCS
FCS
Upper Layer Data
De-encapsulating Data
LLC Hdr + IP + TCP + Upper Layer Data
MAC Header
IP + TCP + Upper Layer Data
LLC Header
TCP+ Upper Layer Data
IP Header
Upper Layer Data
TCP Header
0101110101001000010
Transport
Data Link
Physical
Network
Presentation
Application
Session
Network Device Domains
Hub Bridge Switch Router
Collision Domains:1 4 4 4
Broadcast Domains:1 1 1 4
Hubs Operate at Physical layer
A B C D
Physical
• All devices in the same collision domain• All devices in the same broadcast domain• Devices share the same bandwidth
ffff.ffff.ffff
• Each segment has its own collision domain• All segments are in the same broadcast domain
Data Link
Switches and Bridges Operate at Data Link Layer
OR1 2 3 1 24
Router Operate at Network layer
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255.255.255.255
Question
A B C DA B C D
Broadcast ??
collision ??
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Question
A B C DA B C D
Broadcast ??
collision ??
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Question
A B C DA B C D
Broadcast ??
collision ??
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ABCABC
QuestionBroadcast ?
?collision ??
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Hubs: One Collision DomainHubs: One Collision Domain
• More end stations means more collisions
• CSMA/CD is used
SwitchesSwitches
• Each segment has its own collision domain
• Broadcasts are forwarded to all segments
Memory
Switch
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