osi layers.ppt
TRANSCRIPT
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Advice
Person
Sales
Take
Not
Do
Please
OSI Model Layers
Application
Presentation
Session
Transport
Network
Data Link
Physical
Layer - 7
Layer - 6
Layer - 5
Layer - 4
Layer - 3
Layer - 2
Layer - 1
Upper Layer
or
Software Layer
Lower Layeror
Hardware Layer
Heart of OSI
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Application Layer
Application Layer isresponsible for providingNetworking Services to user.It also known as Desktop Layer.Identification of Services isdone using Port Numbers.
Ports are nothing but Socket i.e.Entry and Exit Point to the Layer
Total No. Ports 0
65535Reserved Ports 0 1023
Open Ports 1024 65535
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
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Example of HTTP request
Client Web Server
http://www.iriset.ac.in
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Example of HTTP request
Client Web Server
HTTP Requesthttp:// www.iriset.ac.in
Webpage
HTTP RequestListen onPort 80
Sending HTTP ReplyWebpage
Received HTTP Replyhttp://www.iriset.ac.in
Webpage
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Example of FTP request
Client FTP Server
ftp://ftp.microsoft.com
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Example of FTP request
FTP Requestftp://ftp.microsoft.com
FTP RequestListen onPort 21
Sending FTP Reply
Received FTP Replyftp://ftp.microsoft.com
Client FTP Server
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Examples of Networking Services
Service Port No.
HTTP 80
FTP 21
SMTP 25
TELNET 23
TFTP 69
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Application
2180 25 6753 69
How data flows from Application Layer
Data
Presentation
Session
Transport
Network
Data Link
Physical
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Presentation Layer
Presentation Layer is
responsible for converting datainto standard format.
Examples : ASCII, EBCDIC, JPEG,MPEG, BMP, MIDI, WAV, MP3
Following tasks are perform atPresentation layer :
Encoding DecodingEncryption Decryption
Compression Decompression
Application
Presentation
Session
Transport
Network
Data Link
Physical
Presentation
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How data flows from Presentation Layer
Data
DataApplication
Presentation
Session
Transport
Network
Data Link
Physical
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Session Layer
Session Layer is responsible
establishing, maintaining andterminating session.
Session ID also works at SessionLayer.
Examples :
RPC Remote Procedure CallSQL Structured Query languageNFS Network File System
Application
Presentation
Session
Transport
Network
Data Link
Physical
Session
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How data flows from Session Layer
Data
Data
Data
Application
Presentation
Session
Transport
Network
Data Link
Physical
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Transport Layer
Transport Layer is
responsible for end-to-endconnectivity. It is also known asheart of OSI Layers. Followingtask are performed at TransportLayer : -
Identifying Service
Multiplexing & De-multiplexing
Segmentation
Sequencing & Reassembling
Flow Control
Error Correction
Application
Presentation
Session
Transport
Network
Data Link
Physical
Transport
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Identifying Service
Transmission Control
Protocol
Connection Oriented
Acknowledgement
Reliable
Slower Port No. 6
e.g. HTTP, FTP, SMTP
User Datagram
Protocol
Connection Less
No Acknowledgement
Unreliable
Faster Port No. 17
e.g. DNS, DHCP, TFTP
TCP UDP
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Application
Presentation
Session
Multiplexing & De-multiplexing
2180 25 6753 69
Transport
TCP - 6 UDP - 17
Network
Data Link
Physical
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Segmentation
Hello! How are you ?
Hello! How Are You ?
Hello!
How areyou ?
A B
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Sequencing & Reassembling
Hello! How are you ?
Hello! How Are You ?
Hello!
How areyou ?
A B
You Hello! How ? Are
Hello! How AreYou ?
youHello!
How ?are
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Sequencing & Reassembling
Hello! How are you ?
Hello!1/5
How2/5
Are3/5
You4/5
?5/5
Hello!
How areyou ?
A B
Hello! How are you ?
Hello!1/5
How2/5
Are3/5
You4/5
?5/5
Hello!1/5
How2/5
Are3/5
You4/5
?5/5
Hello!
How areyou ?
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Error Correction
Hello! How are you ?
Hello!1/5
How2/5
Are3/5
You4/5
?5/5
Hello!
How areyou ? Hello!1/5
Are3/5
You4/5
?5/5
Hello!1/5
Are3/5
You4/5
?5/5
Segment Missing
Hello!1/5
Are3/5
You4/5
?5/5
How2/5
How2/5
Hello! How are you ? Hello!
How areyou ?
A B
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Flow Control - Windowing
Sending
3-window
Received
3-window
Ack-Rec-3
Sending5-window
Received
4-window
A B
Ack.
Received-4
PC-A
can send 4 Segmentat a time to
PC-B
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How data flows from Transport Layer
Data
Data
Data
DataTHSegment
Application
Presentation
Session
Transport
Network
Data Link
Physical
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Network Layer
Network Layer is
responsible for providing bestpath to data to reach destination.Logical Addressing sits on thislayer. Device working on NetworkLayer is Router.
It is divided into two parts
Routed Protocols
e.g. IP, IPX, Apple Talk.
Routing Protocols
e.g. RIP, IGRP, OSPF, EIGRP
Application
Presentation
Session
Transport
Network
Data Link
Physical
Network
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Routed Protocols
Hello!
How areyou ?
192.168.1.1 192.168.1.2
A B
Segment
Segment
Source IP192.168.1.1
Destination IP192.168.1.2
Source IP192.168.1.1
Destination IP192.168.1.2
Segment
Hello!
How areyou ?
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Routing Protocols
A
www.iriset.ac.in
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How data flows from Network Layer
Data
Data
Data
Segment
Segment
NH
e.g. Router
Packet
Application
Presentation
Session
Transport
Network
Data Link
Physical
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Datalink Layer
Datalink Layer is
divided into two Sub Layers :
LLC Logical Link Control
It talks about Wan protocols e.g.PPP, HDLC, Frame-relay
MAC Media Access Control
It talks about Physical Address.It is 48 bit Addressing
i.e. 12 digit Hexadecimal No.It is also responsible for ErrorDetection
Device working on Data LinkLayer is Switch, Bridge, NIC.
Application
Presentation
Session
Transport
Network
Data Link
Physical
Data Link
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Error Detection CRC Check
Hello!
How areyou ?
Packet
Packet
Source MAC00-20-18-C0-07-71
Destination MAC00-20-18-C0-07-72
000003243422222896965543499323434349943446323111143333300000324342222289696554349932343434994344632311114Error Detected
192.168.1.100-20-18-C0-07-71
192.168.1.200-20-18-C0-07-72
A B
PC-A
CRC No. 33333
PC-BCRC No. 11114
Error DetectedFor Error Correction
Contact Source Transport layer
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Error Detection CRC Check
Packet
Packet
Source MAC00-20-18-C0-07-71
Destination MAC00-20-18-C0-07-72
00000324342222289696554349932343434994344632311114202020000032434222228969655434993234343499434463231111420202
Source MAC00-20-18-C0-07-71
Destination MAC00-20-18-C0-07-72
Packet
Hello!
How areyou ?
192.168.1.100-20-18-C0-07-71
192.168.1.200-20-18-C0-07-72
A B
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e.g. Switch
How data flows from Data Link Layer
Data
Data
Data
Segment
DH
Packet
DT
Application
Presentation
Session
Transport
Network
Data Link
Physical
PacketPacketFrame
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Physical Layer
Physical Layer is
responsible for electrical,mechanical or procedural checks.Data will be converted in Binarythat is 0s & 1s. Data will be in the
form of electrical pulses if it is
Coaxial or Twisted Pair cable and inthe form of Light if it is Fiber OpticCable.
Devices working at Physical Layer
are Hubs, Repeaters, Cables,Modems etc.
Application
Presentation
Session
Transport
Network
Data Link
PhysicalPhysical
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Physical Layer Example
Frame
Frame
10101010101010101010101010101010
Frame
Hello!
How areyou ?
A B01010110101010101010101011010101101010101010101010010101101010101010101010110101011010101010101010100101011010101010101010101
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How data flows from Physical Layer
Data
Data
Data
Segment
Packet
Frame
Bits
e.g. Hub
Application
Presentation
Session
Transport
Network
Data Link
Physical
l i l i
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Segment
Packet
Frame
A B
Packet
Data
Data
Data
Bits
Data
Segment
Data Encapsulation & De-capsulation
Packet
Data
Data
Data
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
PhysicalBits
DH DT
NH
THSegment
Packet
DT PacketDH DTDH
NH Segment NH
TH DataTH
Frame Packet
C i OSI i h TCP/IP L
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Application
Transport
Internet
NetworkAccess
Comparing OSI with TCP/IP Layers
OSI Layers TCP/IP Layers
Application
Presentation
Session
Transport
Network
Data Link
Physical
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ftp://ftp.microsoft.com
i f i d [ i ]
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telnet 192.168.1.150
================================
Welcome to Hyderabad Router
================================
User Access Verification
password :
Microsoft Windows 2000 [Version 5.00.2195](C) Copyright 1985-2000 Microsoft Corp.C:\>Connecting .....
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http://www.microsoft.com
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http://mail.yahoo.com
xyz
******