SlideShare uma empresa Scribd logo
1 de 40
Baixar para ler offline
Open Systems
Interconnection
(OSI)
By: Jhoniel Viloria
THE SEVEN OSI
REFERENCE MODEL
LAYERS
LAYER 7: APPLICATION
• The top layer of the OSI model
• The application layer is the OSI layer that is closest to
the user.
• It provides network services to the user’s applications.
• Examples of such applications are spreadsheet
programs, word processing programs, and bank
terminal programs.
LAYER 7: APPLICATION
• It differs from the other layers in that it does not
provide services to any other OSI layer, but rather, only
to applications outside the OSI model.
• The application layer establishes the availability of
intended communication partners, synchronizes and
establishes agreement on procedures for error recovery
and control of data integrity.
LAYER 7: APPLICATION
• Purpose
– User application to network service interface
– The application layer is responsible for
providing services to the user.
• Examples
– File request from server
– E-mail services
– etc.
Application Layer Function
• General network access
• Flow control
• Error recovery
Examples
• Browsers:
– Mozilla Firefox, Internet Explorer, Google Chrome
etc
• Email clients:
– Gmail, Hotmail, Yahoomail and etc.
• FTP clients :
– Filezilla, sFTP, vsFTP
Application Layer Protocols
• SNMP (Simple Network Management Protocol):—
Allows control of networked devices.
• TFTP (Trivial File Transfer Protocol):— Simple,
lightweight file transfer.
• DNS (Domain Naming System):— Translates a
website name (easy for people) to an IP address (easy
for computers).
• DHCP (Dynamic Host Configuration Protocol):—
Assigns IP, mask, and DNS server (plus a bunch of
other stuff) to hosts.
Application Layer Protocols
• Telnet :— Provides a remote terminal connection to
manage devices, which you are not close enough to use
a console cable.
• HTTP (Hypertext Transfer Protocol):— Browse web
pages.
• FTP (File Transfer Protocol):— Reliably
sends/retrieves all file types.
• SMTP (Simple Mail Transfer Protocol):— Sends
email.
• POP3 (Post Office Protocol v.3):— Retrieves email.
• NTP (Network Time Protocol):— Synchronizes
networked device clocks.
LAYER 6: PRESENTATION
• The presentation layer ensures that the information
that the application layer of one system sends out is
readable by the application layer of another system.
• If necessary, the presentation layer translates between
multiple data formats by using a common format.
• Provides encryption and compression of data.
• Examples :- JPEG, MPEG, ASCII, EBCDIC, HTML.
LAYER 6: PRESENTATION
• Purpose
– Formats data for exchange between points
of communication
• Ex: Between nodes in a network
• Example:
– Redirector software
• Formats for transmission to the server
Redirector Example
REDIRECTOR
F:/PUR/ORDER C:/CORRES/USDA
TO SERVER
TO LOCAL
DISK
Presentation Layer Function
• Protocol conversion
• Data translation
• Encryption
• Character set conversion
• Expansion of graphics command
LAYER 5: SESSION
• The session layer defines how to start, control and end
conversations (called sessions) between applications.
• This includes the control and management of multiple bi-
directional messages using dialogue control.
• It also synchronizes dialogue between two hosts'
presentation layers and manages their data exchange.
• The session layer offers provisions for efficient data
transfer.
LAYER 5: SESSION
• Purpose
– Oversee a communication session
• Establish
• Maintain
• Terminate
• Example
– ASP(AppleTalk Session Protocol)
Session Layer Function
• Performs name recognition and related security
• Synchronization between sender and receiver
• Assignment of time for transmission
– Start time
– End time etc.
LAYER 4: TRANSPORT
• The transport layer regulates information flow
to ensure end-to-end connectivity between host
applications reliably and accurately.
• The transport layer segments data from the
sending host's system and reassembles the data
into a data stream on the receiving host's
system.
LAYER 4: TRANSPORT
• The boundary between the transport layer and the
session layer can be thought of as the boundary
between application protocols and data-flow protocols.
Whereas the application, presentation, and session
layers are concerned with application issues, the lower
four layers are concerned with data transport issues.
• Layer 4 protocols include TCP (Transmission Control
Protocol) and UDP (User Datagram Protocol).
LAYER 4: TRANSPORT
• Purpose
– Repackage proper and efficient delivery of
packages
• Error free
• In sequence
• Without duplication
Transport Layer Function
• For sending data
– Repackage the message to fit into packets
• Split long messages
• Assemble small messages
• On receiving data
– Perform the reverse
– Send an acknowledgment to the sender
• Solve packet problems
– During transmission and reception
Transport Layer Function
• Main functions
– Segmentation
– Connection Management
– Reliable and Unreliable data delivery
– Flow control
– Connection Multiplexing
Segmentation
• Segmentation is the process of breaking large data file
into small manageable size that the network can
accommodate. To understand this in easy way, think
about a 700 MB movie that you want to download
from internet. You have 2MBPS internet connection.
How will you download a 700MB movie on 2MBPS
internet connection ?. And the answer is segmentation
process. On server transport layer breaks 700MB
movie in smaller size of segments (less than your
internet connection speed) that your PC can easily
download. Once your browser received all segments
from server, it pop up a message indicating download
completed.
Connection Management
• Transport layer setup, maintain and tear down
connections for session layer. Actual mechanic
of connection is controlled by transport layer.
Transport layer use two protocols for
connection management UDP and TCP.
UDP
• UDP is connection less protocols. Connection-
less transmission is said to be unreliable. Now,
don't get worried about the term "unreliable"
this doesn't mean that the data isn't going to get
its destination; it only means that it isn't
guaranteed to get its destination.
TCP
• TCP is connection oriented protocols.
Connection-oriented transmission is said to be
reliable.
Reliability
Reliability
Once connection established data transmission is
initiated. To provide maximum reliability it cover
these items :
• Detect lost packets and resend them
• Detect packets that arrived out of order and reorder
them
• Recognize duplicate packets and drop extra packet
• Avoid congestion by implementing flow control
Flow Control
The transport layer can implement two
flow control methods:
• Ready/not ready signals
• Windowing
Ready/not ready signals
• In this method sender sends data according to
its buffer size. Receiver receives data in its
buffer. When receivers buffer get filled, it send
a not ready signal to sender, so sender can stop
transmitting more segments. Receivers send
ready signal when it become ready to receive
next segment. There are two problems with the
use of ready/not ready signals to implement
flow control.
Windowing
• In windowing a window size is defined between sender
and receiver. Sender host will wait for an
acknowledgement signal after sending the segments
equal to window size. If any packet lost in way
receiver will respond with acknowledgement for lost
packet. And sender will send lost packet again.
Window size is automatically set during the three step
handshake process. It can be adjust anytime throughout
the lifetime of connection.
Connection Multiplexing/
Application Mapping
• Connection multiplexing features allow multiple
applications to connect at once. For example a server
performs a number of functions like email, FTP, DNS,
Web service, file service, data service etc. Suppose
server has a single IP address, still it can perform all
these different functions for all the hosts that want to
connect with it. To make this possible transport layer
assigns a unique set of numbers for each connection.
These numbers are called port or socket numbers.
These port number allows multiple applications to
simultaneously send and receive data.
Port
Port numbers are divided into ranges. Following are the
current port ranges:
• 0–1023
– Well-Known—For common TCP/IP functions and
applications
• 1024–49151
– Registered—For applications built by companies
• 49152–65535
– Dynamic/Private—For dynamic connections or
unregistered applications
• Common TCP
and UDP ports
Remember
• A convenient aid for
remembering the OSI layer
names is to use the first letter of
each word in the phrase:
• All People Seem To Need
Data Processing
SUMMARY
• There was no standard for networks in the early days
and as a result it was difficult for networks to
communicate with each other.
• The International Organisation for Standardisation
(ISO) recognised this. and researched various network
schemes, and in 1984 introduced the Open Systems
Interconnection (OSI) reference model.
• The OSI reference model has standards which ensure
vendors greater compatibility and interoperability
between various types of network technologies.
SUMMARY
• The OSI reference model organizes network functions
into seven numbered layers.
• Each layer provides a service to the layer above it in the
protocol specification and communicates with the same
layer’s software or hardware on other computers.
• Layers 1-4 are concerned with the flow of data from
end to end through the network and Layers 5-7 are
concerned with services to the applications.
Definition of terms
• SNMP (Simple Network Management Protocol):— Allows control of
networked devices.
• TFTP (Trivial File Transfer Protocol):— Simple, lightweight file
transfer.
• DNS (Domain Naming System):— Translates a website name (easy for
people) to an IP address (easy for computers).
• DHCP (Dynamic Host Configuration Protocol):— Assigns IP, mask,
and DNS server (plus a bunch of other stuff) to hosts.
• Telnet :— Provides a remote terminal connection to manage devices,
which you are not close enough to use a console cable.
• HTTP (Hypertext Transfer Protocol):— Browse web pages.
Definition of terms
• FTP (File Transfer Protocol):— Reliably sends/retrieves all file types.
• SMTP (Simple Mail Transfer Protocol):— Sends email.
• POP3 (Post Office Protocol v.3):— Retrieves email.
• NTP (Network Time Protocol):— Synchronizes networked device
clocks.
• UDP - is connection less protocols.
• Connection-less transmission - is said to be unreliable.
• TCP - is connection oriented protocols.
• Connection-oriented transmission - is said to be reliable.
• Segmentation - is the process of breaking large data file into small
manageable size that the network can accommodate
Definition of terms
• Encryption - is the most effective way to achieve data security.
• Decryption - is the process of converting encrypted data back into its
original form, so it can be understood
• Packet - A packet is the unit of data that is routed between an origin and
a destination on the Internet or any other packet-switched network.
• APS - (AppleTalk Session Protocol)
• Redirector - A special software facility called a “redirector” operates at
this layer to determine if a request is network related on not and forward
network-related requests to an appropriate network resource
References
• http://computernetworkingnotes.com/osi-layer-
modals/osi-model.html
• http://www.gcom.com/files/osi%20model_web.
ppt
• http://mecps.org/konkoth/OSI%20Model.ppt
• http://home.iitk.ac.in/~navi/sidbinetworkcourse
/lecture2.ppt

Mais conteúdo relacionado

Mais procurados

Mais procurados (20)

Dynamic Routing RIP
Dynamic Routing RIPDynamic Routing RIP
Dynamic Routing RIP
 
Network Protocol
Network ProtocolNetwork Protocol
Network Protocol
 
Introduction to VoIP, RTP and SIP
Introduction to VoIP, RTP and SIP Introduction to VoIP, RTP and SIP
Introduction to VoIP, RTP and SIP
 
Ethernet Computer network
Ethernet Computer networkEthernet Computer network
Ethernet Computer network
 
TCP/IP model
TCP/IP modelTCP/IP model
TCP/IP model
 
Presentation on OSI Model
Presentation on OSI ModelPresentation on OSI Model
Presentation on OSI Model
 
Network standards
Network standardsNetwork standards
Network standards
 
OSI model (7 LAYER )
OSI model (7 LAYER )OSI model (7 LAYER )
OSI model (7 LAYER )
 
Ethernet
EthernetEthernet
Ethernet
 
Ethernet
EthernetEthernet
Ethernet
 
Osi , tcp/ip protocol and Addressing
Osi , tcp/ip protocol and Addressing Osi , tcp/ip protocol and Addressing
Osi , tcp/ip protocol and Addressing
 
IP Routing
IP RoutingIP Routing
IP Routing
 
Chapter_5_CN Link Layer.ppt
Chapter_5_CN Link Layer.pptChapter_5_CN Link Layer.ppt
Chapter_5_CN Link Layer.ppt
 
VPLS Fundamental
VPLS FundamentalVPLS Fundamental
VPLS Fundamental
 
transport layer
transport layer transport layer
transport layer
 
Sip architecture
Sip architectureSip architecture
Sip architecture
 
CCNA Chapter1
CCNA Chapter1CCNA Chapter1
CCNA Chapter1
 
VTP
VTPVTP
VTP
 
Tcp/ip
Tcp/ipTcp/ip
Tcp/ip
 
User datagram protocol
User datagram protocolUser datagram protocol
User datagram protocol
 

Destaque (15)

OSI Networking
OSI NetworkingOSI Networking
OSI Networking
 
The OSI Model of Networking
The OSI Model of NetworkingThe OSI Model of Networking
The OSI Model of Networking
 
ISO OSI Model
ISO OSI ModelISO OSI Model
ISO OSI Model
 
Osi model(open system interconnection)
Osi model(open system interconnection)Osi model(open system interconnection)
Osi model(open system interconnection)
 
Osi layer
Osi layerOsi layer
Osi layer
 
Osi model in networking
Osi model in networkingOsi model in networking
Osi model in networking
 
Osi reference model
Osi reference modelOsi reference model
Osi reference model
 
OSI Model - Every Detail Explained
OSI Model - Every Detail ExplainedOSI Model - Every Detail Explained
OSI Model - Every Detail Explained
 
OSI MODEL - A PROJECT
OSI MODEL - A PROJECTOSI MODEL - A PROJECT
OSI MODEL - A PROJECT
 
Osi model
Osi modelOsi model
Osi model
 
TCP-IP Reference Model
TCP-IP Reference ModelTCP-IP Reference Model
TCP-IP Reference Model
 
OSI Model of Networking
OSI Model of NetworkingOSI Model of Networking
OSI Model of Networking
 
OSI Network model ppt
OSI Network model pptOSI Network model ppt
OSI Network model ppt
 
OSI Model
OSI ModelOSI Model
OSI Model
 
7 layer OSI
7 layer OSI7 layer OSI
7 layer OSI
 

Semelhante a Viloria osi layer4-7

IT-NET GROUP 3 REPORT.pptx
IT-NET GROUP 3 REPORT.pptxIT-NET GROUP 3 REPORT.pptx
IT-NET GROUP 3 REPORT.pptxEdJulleza
 
Sargation university's open system interconnection
Sargation university's open system interconnectionSargation university's open system interconnection
Sargation university's open system interconnectionKingPinYT
 
Protocol layer,OSI model & POP3
Protocol layer,OSI model & POP3Protocol layer,OSI model & POP3
Protocol layer,OSI model & POP3Zakirul Islam
 
1_Operating System.ppt
1_Operating System.ppt1_Operating System.ppt
1_Operating System.pptSproohaAthalye
 
Unit 2 ppt-idc
Unit 2 ppt-idcUnit 2 ppt-idc
Unit 2 ppt-idchiya123jes
 
Client Server Network and Peer to Peer.pptx
Client Server Network and Peer to Peer.pptxClient Server Network and Peer to Peer.pptx
Client Server Network and Peer to Peer.pptxDevChaudhari17
 
Networking for MBA
Networking for MBANetworking for MBA
Networking for MBAKK Bajpai
 
Business Information System OSI Model.pptx
Business Information System OSI Model.pptxBusiness Information System OSI Model.pptx
Business Information System OSI Model.pptxssuser34e2f61
 
Osi layer and network protocol
Osi layer and network protocolOsi layer and network protocol
Osi layer and network protocolNayan Sarma
 
OSI Model 2 .ppt
OSI Model 2 .pptOSI Model 2 .ppt
OSI Model 2 .pptAnikGhosh44
 
Linux Inter Process Communication
Linux Inter Process CommunicationLinux Inter Process Communication
Linux Inter Process CommunicationAbhishek Sagar
 
Inter-Process Communication in distributed systems
Inter-Process Communication in distributed systemsInter-Process Communication in distributed systems
Inter-Process Communication in distributed systemsAya Mahmoud
 
open system interconnection referencemodel.ppt
open system interconnection referencemodel.pptopen system interconnection referencemodel.ppt
open system interconnection referencemodel.pptAnkitaAggarwal68
 

Semelhante a Viloria osi layer4-7 (20)

IT-NET GROUP 3 REPORT.pptx
IT-NET GROUP 3 REPORT.pptxIT-NET GROUP 3 REPORT.pptx
IT-NET GROUP 3 REPORT.pptx
 
Sargation university's open system interconnection
Sargation university's open system interconnectionSargation university's open system interconnection
Sargation university's open system interconnection
 
Protocol layer,OSI model & POP3
Protocol layer,OSI model & POP3Protocol layer,OSI model & POP3
Protocol layer,OSI model & POP3
 
Osi
OsiOsi
Osi
 
Iso model
Iso modelIso model
Iso model
 
1_Operating System.ppt
1_Operating System.ppt1_Operating System.ppt
1_Operating System.ppt
 
Unit 2 ppt-idc
Unit 2 ppt-idcUnit 2 ppt-idc
Unit 2 ppt-idc
 
Client Server Network and Peer to Peer.pptx
Client Server Network and Peer to Peer.pptxClient Server Network and Peer to Peer.pptx
Client Server Network and Peer to Peer.pptx
 
OSI Model.ppt
OSI Model.pptOSI Model.ppt
OSI Model.ppt
 
Networking for MBA
Networking for MBANetworking for MBA
Networking for MBA
 
Business Information System OSI Model.pptx
Business Information System OSI Model.pptxBusiness Information System OSI Model.pptx
Business Information System OSI Model.pptx
 
Computer networks
Computer networksComputer networks
Computer networks
 
Osi layer and network protocol
Osi layer and network protocolOsi layer and network protocol
Osi layer and network protocol
 
Bhargava Presentation.ppt
Bhargava Presentation.pptBhargava Presentation.ppt
Bhargava Presentation.ppt
 
Bhargava Presentation.ppt
Bhargava Presentation.pptBhargava Presentation.ppt
Bhargava Presentation.ppt
 
OSI Model 2 .ppt
OSI Model 2 .pptOSI Model 2 .ppt
OSI Model 2 .ppt
 
Linux Inter Process Communication
Linux Inter Process CommunicationLinux Inter Process Communication
Linux Inter Process Communication
 
Inter-Process Communication in distributed systems
Inter-Process Communication in distributed systemsInter-Process Communication in distributed systems
Inter-Process Communication in distributed systems
 
open system interconnection referencemodel.ppt
open system interconnection referencemodel.pptopen system interconnection referencemodel.ppt
open system interconnection referencemodel.ppt
 
lecture 4.pptx
lecture 4.pptxlecture 4.pptx
lecture 4.pptx
 

Último

Benefits of doing Internet peering and running an Internet Exchange (IX) pres...
Benefits of doing Internet peering and running an Internet Exchange (IX) pres...Benefits of doing Internet peering and running an Internet Exchange (IX) pres...
Benefits of doing Internet peering and running an Internet Exchange (IX) pres...APNIC
 
Introduction to ICANN and Fellowship program by Shreedeep Rayamajhi.pdf
Introduction to ICANN and Fellowship program  by Shreedeep Rayamajhi.pdfIntroduction to ICANN and Fellowship program  by Shreedeep Rayamajhi.pdf
Introduction to ICANN and Fellowship program by Shreedeep Rayamajhi.pdfShreedeep Rayamajhi
 
TYPES AND DEFINITION OF ONLINE CRIMES AND HAZARDS
TYPES AND DEFINITION OF ONLINE CRIMES AND HAZARDSTYPES AND DEFINITION OF ONLINE CRIMES AND HAZARDS
TYPES AND DEFINITION OF ONLINE CRIMES AND HAZARDSedrianrheine
 
Check out the Free Landing Page Hosting in 2024
Check out the Free Landing Page Hosting in 2024Check out the Free Landing Page Hosting in 2024
Check out the Free Landing Page Hosting in 2024Shubham Pant
 
LESSON 10/ GROUP 10/ ST. THOMAS AQUINASS
LESSON 10/ GROUP 10/ ST. THOMAS AQUINASSLESSON 10/ GROUP 10/ ST. THOMAS AQUINASS
LESSON 10/ GROUP 10/ ST. THOMAS AQUINASSlesteraporado16
 
Vision Forward: Tracing Image Search SEO From Its Roots To AI-Enhanced Horizons
Vision Forward: Tracing Image Search SEO From Its Roots To AI-Enhanced HorizonsVision Forward: Tracing Image Search SEO From Its Roots To AI-Enhanced Horizons
Vision Forward: Tracing Image Search SEO From Its Roots To AI-Enhanced HorizonsRoxana Stingu
 
LESSON 5 GROUP 10 ST. THOMAS AQUINAS.pdf
LESSON 5 GROUP 10 ST. THOMAS AQUINAS.pdfLESSON 5 GROUP 10 ST. THOMAS AQUINAS.pdf
LESSON 5 GROUP 10 ST. THOMAS AQUINAS.pdfmchristianalwyn
 
Presentation2.pptx - JoyPress Wordpress
Presentation2.pptx -  JoyPress WordpressPresentation2.pptx -  JoyPress Wordpress
Presentation2.pptx - JoyPress Wordpressssuser166378
 
Zero-day Vulnerabilities
Zero-day VulnerabilitiesZero-day Vulnerabilities
Zero-day Vulnerabilitiesalihassaah1994
 
WordPress by the numbers - Jan Loeffler, CTO WebPros, CloudFest 2024
WordPress by the numbers - Jan Loeffler, CTO WebPros, CloudFest 2024WordPress by the numbers - Jan Loeffler, CTO WebPros, CloudFest 2024
WordPress by the numbers - Jan Loeffler, CTO WebPros, CloudFest 2024Jan Löffler
 
Bio Medical Waste Management Guideliness 2023 ppt.pptx
Bio Medical Waste Management Guideliness 2023 ppt.pptxBio Medical Waste Management Guideliness 2023 ppt.pptx
Bio Medical Waste Management Guideliness 2023 ppt.pptxnaveenithkrishnan
 
Computer 10 Lesson 8: Building a Website
Computer 10 Lesson 8: Building a WebsiteComputer 10 Lesson 8: Building a Website
Computer 10 Lesson 8: Building a WebsiteMavein
 

Último (12)

Benefits of doing Internet peering and running an Internet Exchange (IX) pres...
Benefits of doing Internet peering and running an Internet Exchange (IX) pres...Benefits of doing Internet peering and running an Internet Exchange (IX) pres...
Benefits of doing Internet peering and running an Internet Exchange (IX) pres...
 
Introduction to ICANN and Fellowship program by Shreedeep Rayamajhi.pdf
Introduction to ICANN and Fellowship program  by Shreedeep Rayamajhi.pdfIntroduction to ICANN and Fellowship program  by Shreedeep Rayamajhi.pdf
Introduction to ICANN and Fellowship program by Shreedeep Rayamajhi.pdf
 
TYPES AND DEFINITION OF ONLINE CRIMES AND HAZARDS
TYPES AND DEFINITION OF ONLINE CRIMES AND HAZARDSTYPES AND DEFINITION OF ONLINE CRIMES AND HAZARDS
TYPES AND DEFINITION OF ONLINE CRIMES AND HAZARDS
 
Check out the Free Landing Page Hosting in 2024
Check out the Free Landing Page Hosting in 2024Check out the Free Landing Page Hosting in 2024
Check out the Free Landing Page Hosting in 2024
 
LESSON 10/ GROUP 10/ ST. THOMAS AQUINASS
LESSON 10/ GROUP 10/ ST. THOMAS AQUINASSLESSON 10/ GROUP 10/ ST. THOMAS AQUINASS
LESSON 10/ GROUP 10/ ST. THOMAS AQUINASS
 
Vision Forward: Tracing Image Search SEO From Its Roots To AI-Enhanced Horizons
Vision Forward: Tracing Image Search SEO From Its Roots To AI-Enhanced HorizonsVision Forward: Tracing Image Search SEO From Its Roots To AI-Enhanced Horizons
Vision Forward: Tracing Image Search SEO From Its Roots To AI-Enhanced Horizons
 
LESSON 5 GROUP 10 ST. THOMAS AQUINAS.pdf
LESSON 5 GROUP 10 ST. THOMAS AQUINAS.pdfLESSON 5 GROUP 10 ST. THOMAS AQUINAS.pdf
LESSON 5 GROUP 10 ST. THOMAS AQUINAS.pdf
 
Presentation2.pptx - JoyPress Wordpress
Presentation2.pptx -  JoyPress WordpressPresentation2.pptx -  JoyPress Wordpress
Presentation2.pptx - JoyPress Wordpress
 
Zero-day Vulnerabilities
Zero-day VulnerabilitiesZero-day Vulnerabilities
Zero-day Vulnerabilities
 
WordPress by the numbers - Jan Loeffler, CTO WebPros, CloudFest 2024
WordPress by the numbers - Jan Loeffler, CTO WebPros, CloudFest 2024WordPress by the numbers - Jan Loeffler, CTO WebPros, CloudFest 2024
WordPress by the numbers - Jan Loeffler, CTO WebPros, CloudFest 2024
 
Bio Medical Waste Management Guideliness 2023 ppt.pptx
Bio Medical Waste Management Guideliness 2023 ppt.pptxBio Medical Waste Management Guideliness 2023 ppt.pptx
Bio Medical Waste Management Guideliness 2023 ppt.pptx
 
Computer 10 Lesson 8: Building a Website
Computer 10 Lesson 8: Building a WebsiteComputer 10 Lesson 8: Building a Website
Computer 10 Lesson 8: Building a Website
 

Viloria osi layer4-7

  • 2. THE SEVEN OSI REFERENCE MODEL LAYERS
  • 3. LAYER 7: APPLICATION • The top layer of the OSI model • The application layer is the OSI layer that is closest to the user. • It provides network services to the user’s applications. • Examples of such applications are spreadsheet programs, word processing programs, and bank terminal programs.
  • 4. LAYER 7: APPLICATION • It differs from the other layers in that it does not provide services to any other OSI layer, but rather, only to applications outside the OSI model. • The application layer establishes the availability of intended communication partners, synchronizes and establishes agreement on procedures for error recovery and control of data integrity.
  • 5. LAYER 7: APPLICATION • Purpose – User application to network service interface – The application layer is responsible for providing services to the user. • Examples – File request from server – E-mail services – etc.
  • 6. Application Layer Function • General network access • Flow control • Error recovery
  • 7. Examples • Browsers: – Mozilla Firefox, Internet Explorer, Google Chrome etc • Email clients: – Gmail, Hotmail, Yahoomail and etc. • FTP clients : – Filezilla, sFTP, vsFTP
  • 8. Application Layer Protocols • SNMP (Simple Network Management Protocol):— Allows control of networked devices. • TFTP (Trivial File Transfer Protocol):— Simple, lightweight file transfer. • DNS (Domain Naming System):— Translates a website name (easy for people) to an IP address (easy for computers). • DHCP (Dynamic Host Configuration Protocol):— Assigns IP, mask, and DNS server (plus a bunch of other stuff) to hosts.
  • 9. Application Layer Protocols • Telnet :— Provides a remote terminal connection to manage devices, which you are not close enough to use a console cable. • HTTP (Hypertext Transfer Protocol):— Browse web pages. • FTP (File Transfer Protocol):— Reliably sends/retrieves all file types. • SMTP (Simple Mail Transfer Protocol):— Sends email. • POP3 (Post Office Protocol v.3):— Retrieves email. • NTP (Network Time Protocol):— Synchronizes networked device clocks.
  • 10. LAYER 6: PRESENTATION • The presentation layer ensures that the information that the application layer of one system sends out is readable by the application layer of another system. • If necessary, the presentation layer translates between multiple data formats by using a common format. • Provides encryption and compression of data. • Examples :- JPEG, MPEG, ASCII, EBCDIC, HTML.
  • 11. LAYER 6: PRESENTATION • Purpose – Formats data for exchange between points of communication • Ex: Between nodes in a network • Example: – Redirector software • Formats for transmission to the server
  • 13. Presentation Layer Function • Protocol conversion • Data translation • Encryption • Character set conversion • Expansion of graphics command
  • 14. LAYER 5: SESSION • The session layer defines how to start, control and end conversations (called sessions) between applications. • This includes the control and management of multiple bi- directional messages using dialogue control. • It also synchronizes dialogue between two hosts' presentation layers and manages their data exchange. • The session layer offers provisions for efficient data transfer.
  • 15. LAYER 5: SESSION • Purpose – Oversee a communication session • Establish • Maintain • Terminate • Example – ASP(AppleTalk Session Protocol)
  • 16. Session Layer Function • Performs name recognition and related security • Synchronization between sender and receiver • Assignment of time for transmission – Start time – End time etc.
  • 17. LAYER 4: TRANSPORT • The transport layer regulates information flow to ensure end-to-end connectivity between host applications reliably and accurately. • The transport layer segments data from the sending host's system and reassembles the data into a data stream on the receiving host's system.
  • 18. LAYER 4: TRANSPORT • The boundary between the transport layer and the session layer can be thought of as the boundary between application protocols and data-flow protocols. Whereas the application, presentation, and session layers are concerned with application issues, the lower four layers are concerned with data transport issues. • Layer 4 protocols include TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
  • 19. LAYER 4: TRANSPORT • Purpose – Repackage proper and efficient delivery of packages • Error free • In sequence • Without duplication
  • 20. Transport Layer Function • For sending data – Repackage the message to fit into packets • Split long messages • Assemble small messages • On receiving data – Perform the reverse – Send an acknowledgment to the sender • Solve packet problems – During transmission and reception
  • 21. Transport Layer Function • Main functions – Segmentation – Connection Management – Reliable and Unreliable data delivery – Flow control – Connection Multiplexing
  • 22. Segmentation • Segmentation is the process of breaking large data file into small manageable size that the network can accommodate. To understand this in easy way, think about a 700 MB movie that you want to download from internet. You have 2MBPS internet connection. How will you download a 700MB movie on 2MBPS internet connection ?. And the answer is segmentation process. On server transport layer breaks 700MB movie in smaller size of segments (less than your internet connection speed) that your PC can easily download. Once your browser received all segments from server, it pop up a message indicating download completed.
  • 23. Connection Management • Transport layer setup, maintain and tear down connections for session layer. Actual mechanic of connection is controlled by transport layer. Transport layer use two protocols for connection management UDP and TCP.
  • 24. UDP • UDP is connection less protocols. Connection- less transmission is said to be unreliable. Now, don't get worried about the term "unreliable" this doesn't mean that the data isn't going to get its destination; it only means that it isn't guaranteed to get its destination.
  • 25. TCP • TCP is connection oriented protocols. Connection-oriented transmission is said to be reliable.
  • 27. Reliability Once connection established data transmission is initiated. To provide maximum reliability it cover these items : • Detect lost packets and resend them • Detect packets that arrived out of order and reorder them • Recognize duplicate packets and drop extra packet • Avoid congestion by implementing flow control
  • 28. Flow Control The transport layer can implement two flow control methods: • Ready/not ready signals • Windowing
  • 29. Ready/not ready signals • In this method sender sends data according to its buffer size. Receiver receives data in its buffer. When receivers buffer get filled, it send a not ready signal to sender, so sender can stop transmitting more segments. Receivers send ready signal when it become ready to receive next segment. There are two problems with the use of ready/not ready signals to implement flow control.
  • 30. Windowing • In windowing a window size is defined between sender and receiver. Sender host will wait for an acknowledgement signal after sending the segments equal to window size. If any packet lost in way receiver will respond with acknowledgement for lost packet. And sender will send lost packet again. Window size is automatically set during the three step handshake process. It can be adjust anytime throughout the lifetime of connection.
  • 31. Connection Multiplexing/ Application Mapping • Connection multiplexing features allow multiple applications to connect at once. For example a server performs a number of functions like email, FTP, DNS, Web service, file service, data service etc. Suppose server has a single IP address, still it can perform all these different functions for all the hosts that want to connect with it. To make this possible transport layer assigns a unique set of numbers for each connection. These numbers are called port or socket numbers. These port number allows multiple applications to simultaneously send and receive data.
  • 32. Port Port numbers are divided into ranges. Following are the current port ranges: • 0–1023 – Well-Known—For common TCP/IP functions and applications • 1024–49151 – Registered—For applications built by companies • 49152–65535 – Dynamic/Private—For dynamic connections or unregistered applications
  • 33. • Common TCP and UDP ports
  • 34. Remember • A convenient aid for remembering the OSI layer names is to use the first letter of each word in the phrase: • All People Seem To Need Data Processing
  • 35. SUMMARY • There was no standard for networks in the early days and as a result it was difficult for networks to communicate with each other. • The International Organisation for Standardisation (ISO) recognised this. and researched various network schemes, and in 1984 introduced the Open Systems Interconnection (OSI) reference model. • The OSI reference model has standards which ensure vendors greater compatibility and interoperability between various types of network technologies.
  • 36. SUMMARY • The OSI reference model organizes network functions into seven numbered layers. • Each layer provides a service to the layer above it in the protocol specification and communicates with the same layer’s software or hardware on other computers. • Layers 1-4 are concerned with the flow of data from end to end through the network and Layers 5-7 are concerned with services to the applications.
  • 37. Definition of terms • SNMP (Simple Network Management Protocol):— Allows control of networked devices. • TFTP (Trivial File Transfer Protocol):— Simple, lightweight file transfer. • DNS (Domain Naming System):— Translates a website name (easy for people) to an IP address (easy for computers). • DHCP (Dynamic Host Configuration Protocol):— Assigns IP, mask, and DNS server (plus a bunch of other stuff) to hosts. • Telnet :— Provides a remote terminal connection to manage devices, which you are not close enough to use a console cable. • HTTP (Hypertext Transfer Protocol):— Browse web pages.
  • 38. Definition of terms • FTP (File Transfer Protocol):— Reliably sends/retrieves all file types. • SMTP (Simple Mail Transfer Protocol):— Sends email. • POP3 (Post Office Protocol v.3):— Retrieves email. • NTP (Network Time Protocol):— Synchronizes networked device clocks. • UDP - is connection less protocols. • Connection-less transmission - is said to be unreliable. • TCP - is connection oriented protocols. • Connection-oriented transmission - is said to be reliable. • Segmentation - is the process of breaking large data file into small manageable size that the network can accommodate
  • 39. Definition of terms • Encryption - is the most effective way to achieve data security. • Decryption - is the process of converting encrypted data back into its original form, so it can be understood • Packet - A packet is the unit of data that is routed between an origin and a destination on the Internet or any other packet-switched network. • APS - (AppleTalk Session Protocol) • Redirector - A special software facility called a “redirector” operates at this layer to determine if a request is network related on not and forward network-related requests to an appropriate network resource
  • 40. References • http://computernetworkingnotes.com/osi-layer- modals/osi-model.html • http://www.gcom.com/files/osi%20model_web. ppt • http://mecps.org/konkoth/OSI%20Model.ppt • http://home.iitk.ac.in/~navi/sidbinetworkcourse /lecture2.ppt