CCNACisco Certified Network Associate

640-802

www.arabhardware.net

Mohammedsn

علما ” ” زدني رب قل و تعالي قال

OSI 7 layerOSI 7 layer

OSI Open System InterconnectionOSI Open System Interconnection

We 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)

www.arabhardware.net

Mohammedsn

33

OSI Model OverviewOSI Model OverviewOSI Model OverviewOSI Model Overview

Data Flow Layers

Transport Layer

Data Link

Network Layer

Physical

Application (Upper) Layers

Session

Presentation

Application

www.arabhardware.net

Mohammedsn

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

www.arabhardware.net

Mohammedsn

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)

www.arabhardware.net

Mohammedsn

55 - -session layersession layer

Set a logical connection ( session) Set a logical connection ( session) between different applicationbetween different application

Specifies communication mode Specifies communication mode

( simple - Half duplex – full duplex ) ( simple - Half duplex – full duplex )

www.arabhardware.net

Mohammedsn

44 - -Transport layerTransport layer

Flow control Flow control

Error recovery Error recovery

www.arabhardware.net

Mohammedsn

Flow controlFlow control

Pc1 Pc2

stop

Go on

BufferingCongestion avoidence

www.arabhardware.net

Mohammedsn

WindowingWindowingWindowingWindowing

Sender Receiver

www.arabhardware.net

Mohammedsn

WindowingWindowingWindowingWindowing

Window size = 3Send 2

Sender ReceiverWindow size = 3Send 1

Window size = 3Send 3

www.arabhardware.net

Mohammedsn

Window size = 3Send 2

WindowingWindowingWindowingWindowing

Sender Window size = 3Send 1

Window size = 3Send 3

ACK 3Window size = 2

Packet 3 isDropped

Receiver

www.arabhardware.net

Mohammedsn

Window size = 3Send 2

WindowingWindowingWindowingWindowing

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

www.arabhardware.net

Mohammedsn

Window size = 3Send 2

WindowingWindowingWindowingWindowing

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

www.arabhardware.net

Mohammedsn

TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment Numbers

TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment Numbers

SourcePort

SourcePort

Dest.Port

Dest.Port

……Sequence#

Sequence#

Acknowledgement#

Acknowledgement#

Source Dest. Seq. Ack.

1028 23 10 1

I justsent #10.

www.arabhardware.net

Mohammedsn

TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment Numbers

I just got #10,now I need #11.

SourcePort

SourcePort

Dest.Port

Dest.Port ……

Sequence#

Sequence#

Acknowledgement#

Acknowledgement#

10281028 2323

Source Dest.

10101010

Seq.

11

Ack.

102810282323

Source Dest.

11111111

Seq.

11

Ack.

I justsent #10.

www.arabhardware.net

Mohammedsn

TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment Numbers

TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment NumbersSource

PortSource

PortDest.Port

Dest.Port ……

Sequence#

Sequence#

Acknowledgement#

Acknowledgement#

10281028 2323

Source Dest.

11111111

Seq.

22

Ack.

10281028 2323

Source Dest.

10101010

Seq.

11

Ack.

102810282323

Source Dest.

11111111

Seq.

11

Ack.

I just got #10,now I need #11.

I justsent #11.

www.arabhardware.net

Mohammedsn

TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment Numbers

TCP Sequence and TCP Sequence and Acknowledgment NumbersAcknowledgment NumbersSource

PortSource

PortDest.Port

Dest.Port ……

Sequence#

Sequence#

Acknowledgement#

Acknowledgement#

10281028 2323

Source Dest.

11111111

Seq.

22

Ack.

10281028 2323

Source Dest.

10101010

Seq.

11

Ack.

102810282323

Source Dest.

11111111

Seq.

11

Ack.

102810282323

Source Dest.

12121212

Seq.

22

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

www.arabhardware.net

Mohammedsn

3-Network layer

1-routing 2-IP addressing

www.arabhardware.net

Mohammedsn

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 week

2-CRC : Depend on mathematical equation 2-CRC : Depend on mathematical equation

www.arabhardware.net

Mohammedsn

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)

www.arabhardware.net

Mohammedsn

MAC address : hardware address

48 bit

24 bit ( vendor) 24 bit IEEE

LLC sub layerLLC sub layer

TCP/IPTCP/IP SPX/IPXSPX/IPX

www.arabhardware.net

Mohammedsn

Physical Layer: Physical Layer: Ethernet/802.3Ethernet/802.3Physical Layer: Physical Layer: Ethernet/802.3Ethernet/802.3

Hub

Hosts

Host

10Base2—Thin Ethernet10Base5—Thick Ethernet

10BaseT—Twisted Pair

www.arabhardware.net

Mohammedsn

Encapsulating DataEncapsulating 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 DataDe-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 DomainsNetwork Device Domains

Hub Bridge Switch Router

Collision Domains:

1 4 4 4 Broadcast Domains:

1 1 1 4

Hubs Operate at Physical layerHubs 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

Switches and Bridges Operate at Data Link Layer

OR1 2 3 1 24

Router Operate at Network layerRouter Operate at Network layer

www.arabhardware.net

Mohammedsn

255.255.255.255

QuestionQuestion

A B C DA B C D

Broadcast ??

Broadcast ??

collision ??collision ??

www.arabhardware.net

Mohammedsn

QuestionQuestion

A B C DA B C D

Broadcast ??

Broadcast ??

collision ??collision ??

www.arabhardware.net

Mohammedsn

QuestionQuestion

A B C DA B C D

Broadcast ??

Broadcast ??

collision ??collision ??

www.arabhardware.net

Mohammedsn

ABCABC

QuestionQuestion

Broadcast ??

Broadcast ??

collision ??collision ??

www.arabhardware.net

Mohammedsn

Hubs: One Collision DomainHubs: One Collision DomainHubs: One Collision DomainHubs: One Collision Domain

• More end stations means more collisions

• CSMA/CD is used

SwitchesSwitchesSwitchesSwitches

• Each segment has its own collision domain

• Broadcasts are forwarded to all segments

Memory

Switch