This slides covers - Application layer functionality - Presentation layer functionality - Session layer functionality - Communication types over Application layer - Application layer components - Application layer protocol functions - Application layer protocols

1. Network Fundamentals – Application Layer Functionality and Protocols
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Ahmed Hamed Attia Kotb Hussein Teaching Assistant CS Department
By
Ahmed Hamed Attia Kotb
ahmed_hamed@ci.suez.edu.eg
+201227253795
Application Layer Functionality
and Protocols
chapter 3

2. Agenda
• Application layer functionality
• Presentation layer functionality
• Session layer functionality
• Communication types over Application layer
• Application layer components
• Application layer protocol functions
• Application layer protocols
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Ahmed Hamed Attia Kotb Hussein Teaching Assistant CS Department
Network Fundamentals – Application Layer Functionality and Protocols

3. Application Layer
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• Interface between end
users and the
underlying network
infrastructure
• Used to exchange data
between the running
applications in both
sender and receiver.
Network Fundamentals – Application Layer Functionality and Protocols

4. Presentation Layer
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• Coding and conversion of Application layer data to
ensure data from source can be interpreted by the
destination.
• Compression.
• Encryption.
Network Fundamentals – Application Layer Functionality and Protocols

5. Session Layer
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• Create and maintain the dialogs
between the source host and the
destination host.
Network Fundamentals – Application Layer Functionality and Protocols

6. Communication types over Application
layer
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• Client / Server model.
• Daemon process.
• Data transfer from a client
to a server is referred to as
an upload and data from a
server to a client as a
download.
Network Fundamentals – Application Layer Functionality and Protocols

7. Communication types over Application
layer
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• Peer to Peer (p2p) model.
• All Share resources
• Each device operates as
client and server in the
same time
Network Fundamentals – Application Layer Functionality and Protocols

8. Application Layer Components
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• Application software.
• Network aware application
• Processes / Services.
• Protocols.
Network Fundamentals – Application Layer Functionality and Protocols

9. 9
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• Application layer protocol functions
• Define the process on either ends.
• Defines the type of the message.
• Define the syntax of the message.
• Define how the messages are sent and the
excepted response.
Network Fundamentals – Application Layer Functionality and Protocols
Application Layer Protocols

10. Application Layer Protocols
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• Examples of Application layer protocols:
• DNS
• HTTP
• SMTP / POP
• FTP
• DHCP
• SMB
• Telnet
Network Fundamentals – Application Layer Functionality and Protocols

11. Domain Name System (DNS)
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• DNS resolver: Resolves names to its associated IP
Network Fundamentals – Application Layer Functionality and Protocols

12. Domain Name System (DNS)
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• DNS resolver: Resolves names to its associated IP
Network Fundamentals – Application Layer Functionality and Protocols

13. Domain Name System (DNS)
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• Nslookup command.
Network Fundamentals – Application Layer Functionality and Protocols

14. Domain Name System (DNS)
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• DNS records
• A – end device
• NS – authoritative Name System
• CNAME – Canonical Name.
• MX – Mail Exchange
• ipconfig / displaydns
Network Fundamentals – Application Layer Functionality and Protocols

15. Domain Name System (DNS)
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• DNS resolving process
• www.mail.cisco.com
Network Fundamentals – Application Layer Functionality and Protocols

16. Hyper Text Transfer Protocol
(HTTP)
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• HTTP specifies a request/response protocol. When a client, typically
a web browser, sends a request message to a server, the HTTP
protocol defines the message types the client uses to request the web
page and also the message types the server uses to respond.
• The three common message types are GET, POST, and PUT.
• No authentication, No encryption.
• HTTPS uses both authentication and encryption.
Network Fundamentals – Application Layer Functionality and Protocols

17. Simple Mail Transfer Protocol
(SMTP) / Post Office Protocol (POP)
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• Both together are used to provide the E-mail services.
• MUA
• MTA
• MDA
Network Fundamentals – Application Layer Functionality and Protocols

18. Simple Mail Transfer Protocol
(SMTP) / Post Office Protocol (POP)
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• Both together are used to provide the E-mail services.
• MUA
• MTA
• MDA
Network Fundamentals – Application Layer Functionality and Protocols

19. Simple Mail Transfer Protocol
(SMTP) / Post Office Protocol (POP)
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• SMTP uses set of commands to support the mailing services
• HELO
• EHLO
• Mail From
• RCPT To
• DATA
Network Fundamentals – Application Layer Functionality and Protocols

20. File Transfer Protocol (FTP)
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• FTP was developed to allow for file transfers between a client and a
server.
• An FTP client is an application that runs on a computer that is used to
push and pull files from a server running the FTP daemon (FTPd).
• The client establishes the first connection to the server on TCP port 21.
This connection is used for control traffic, consisting of client commands
and server replies.
• The client establishes the second connection to the server over TCP port
20. This connection is for the actual file transfer and is created every time
there is a file transferred.
Network Fundamentals – Application Layer Functionality and Protocols

21. Dynamic Host Configuration Protocol
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Network Fundamentals – Application Layer Functionality and Protocols

22. Server Message Block
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• Once the connection is established, the user of the client can access the
resources on the server as if the resource is local to the client host.
Network Fundamentals – Application Layer Functionality and Protocols

23. Telnet
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• Connection using Telnet is called a Virtual Terminal
(VTY) session, or connection. Rather than using a physical
device to connect to the server, Telnet uses software to
create a virtual device that provides the same features of a
terminal session with access to the server command line
interface (CLI).
• Not secure, No Encryption
• Secure Shell (SSH)
Network Fundamentals – Application Layer Functionality and Protocols

24. Thank you
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Network Fundamentals – Application Layer Functionality and Protocols