CCN Unit-5 Transport & Application Layer by Adi.pdf

CCN Unit-5 Transport & Application Layer by Dr. K. Adisesha

1. CCN Unit-5
Transport Layer &
Application Layer
DR. K. ADISESHA

2. Introduction
to
Networks-5
Introduction
Transport Layer
Transport Layer Protocols
Application Layer
Application Layer Protocols
2
Transport Layer
&
Application Layer
Dr. K. Adisesha

3. Introduction
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3
Transport Layer:
The transport Layer is the second layer in the TCP/IP model and the fourth layer in the
OSI model. It is an end-to-end layer used to deliver messages to a host.
➢The transport layer takes services from the Application layer and provides services to
the Network layer.
➢The unit of data encapsulation in the Transport Layer is a segment.
➢It is termed an end-to-end layer because it
provides a point-to-point connection rather
than hop-to-hop, between the source host and
destination host to deliver the services reliably.

4. Introduction
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Transport Layer:
The transport Layer is the second layer in the TCP/IP model and the fourth layer in the
OSI model. It is an end-to-end layer used to deliver messages to a host.
➢Responsibilities of a Transport Layer
❖The Process to Process Delivery
❖End-to-End Connection between Hosts
❖Multiplexing and Demultiplexing
❖Congestion Control
❖Data integrity and Error correction
❖Flow control

5. Transport Layer Services
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Services provided by the Transport Layer:
Transport layer provides the services across an internetwork made up of many
networks.
➢End-to-end delivery: The transport layer transmits the entire message to the
destination. Therefore, it ensures the end-to-end delivery of an entire message from a
source to the destination.
➢Reliable delivery: The transport layer provides reliability services by retransmitting
the lost and damaged packets. The reliable delivery has four aspects:
❖Error control
❖Sequence control
❖Loss control
❖Duplication control

6. Transport Layer Services
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Services provided by the Transport Layer:
Transport layer provides the services across an internetwork made up of many
networks.
➢Flow Control: Flow control is used to prevent the sender from overwhelming the
receiver. It uses the sliding window protocol.
❖This increases network congestion and thus, reducing the system performance.
➢Multiplexing: Multiplexing is when data is acquired from several processes from the
sender and merged into one packet along with headers and sent as a single packet.
❖Upward multiplexing: Upward multiplexing means multiple transport layer connections
use the same network connection.
❖Downward multiplexing: This type of multiplexing is used when networks have a low or
slow capacity.

7. Transport Layer Protocols
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Transport Layer Protocols:
The transport layer protocols define some connections to individual ports known as
protocol ports.
➢Each port is defined by a positive integer address, and it is of 16 bits.
➢Transport Layer Protocols:
❖Transmission Control Protocol (TCP): It
provides reliable communication between
two hosts.
❖User Datagram Protocol (UDP): It provides
unreliable communication between two hosts.

8. Transport Layer Protocols
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User Datagram Protocol:
UDP is one of the simplest transport layer protocols which provides non-sequenced
data transmission functionality.
➢It is an end-to-end transport-level protocol that adds transport-level addresses,
checksum error control, and length information to the data received from the upper
layer.
❖UDP is a connectionless protocol.
❖This type of protocol is used when reliability and security are
less important than speed and size.
❖The packet produced by the UDP protocol is known as a user
datagram.
❖The user datagram has a header consisting of four fields

9. User Datagram Protocol
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Features of UDP protocol:
The following are the features of the UDP protocol:
➢Transport layer protocol: UDP is the simplest transport layer communication protocol.
It contains a minimum amount of communication mechanisms.
➢Connectionless: The UDP is a connectionless protocol as it does not create a virtual
path to transfer the data. It does not use the virtual path, which leads to the loss of
packets or received out of order.
➢Ordered delivery of data is not guaranteed: In the case of UDP, the datagrams are sent
in some order will be received in the same order is not guaranteed as the datagrams
are not numbered.

10. User Datagram Protocol
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Features of UDP protocol:
The following are the features of the UDP protocol:
➢Ports: The UDP protocol uses different port numbers so that the data can be sent to
the correct destination. The port numbers are defined between 0 and 1023.
➢Faster transmission: UDP enables faster transmission as it is a connectionless
protocol, But there is a chance that the individual packet is lost, which affects the
transmission quality.
➢Acknowledgment mechanism: The UDP does have any acknowledgment mechanism,
i.e., there is no handshaking between the UDP sender and UDP receiver.
➢Segments are handled independently: Each UDP segment is handled individually of
others as each segment takes different path to reach the destination.

11. Transport Layer Protocols
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User Datagram Protocol:
UDP is one of the simplest transport layer protocols which provides nonsequenced data
transmission functionality.
➢Here are few applications where UDP is used to transmit data:
❖Domain Name Services
❖Simple Network Management Protocol
❖Trivial File Transfer Protocol
❖Routing Information Protocol
❖Kerberos

12. Transport Layer Protocols
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User Datagram Protocol:
UDP is one of the simplest transport layer protocols which provides nonsequenced data
transmission functionality.
➢Disadvantages of UDP protocol:
❖UDP provides basic functions needed for the end-to-end delivery
of a transmission.
❖It does not provide any sequencing or reordering functions and
does not specify the damaged packet when reporting an error.
❖UDP can discover that an error has occurred, but it does not
specify which packet has been lost as it does not contain an ID
or sequencing number of a particular data segment.

13. Transport Layer Protocols
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Transmission Control Protocol:
TCP is connection oriented. TCP requires that connection between two remote points
be established before sending actual data.
➢TCP is a connection-oriented transport layer protocol.
❖It is most widely used protocol for data transmission in
communication network such as internet.
❖TCP ensures that the data reaches intended destination in the
same order it was sent.
❖TCP operates in Client/Server point-to-point mode.
❖TCP provides full duplex server, i.e. it can perform roles of both
receiver and sender.
❖The length of TCP header is minimum 20 bytes long and
maximum 60 bytes.

14. Transmission Control Protocol
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Connection Management of TCP:
TCP communication works in Server/Client model. The client initiates the connection
and the server either accepts or rejects it.
➢Three-way handshaking is used for connection management.
❖Establishment: Client initiates the connection and sends the segment
with a Sequence number.
oACK - It indicates that Acknowledgement field has significance. If ACK
is cleared to 0, it indicates that packet does not contain any
acknowledgement.
oSYN - This flag is used to set up a connection between hosts.
❖Release: Either of server and client can send TCP segment with FIN
flag set to 1.

15. Basis for Comparison TCP UDP
Definition TCPestablishesavirtualcircuit
beforetransmittingthedata.
UDPtransmitsthedatadirectlytothe
destinationcomputerwithoutverifying
thereceiverisreadytoreceiveornot.
ConnectionType ItisaConnection-OrientedprotocolItisaConnectionlessprotocol
Speed slow high
Reliability Itisareliableprotocol. Itisanunreliableprotocol.
Headersize 20bytes 8bytes
acknowledgement Itwaitsfortheacknowledgementof
dataandhastheabilitytoresendthe
lostpackets.
Itneithertakestheacknowledgement,
noritretransmitsthedamagedframe.
Transmission Control Protocol
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Differences between TCP & UDP:

16. Application Layer
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Application Layer:
Application layer is the top most layer in OSI and TCP/IP layered model for
applications which are involved in communication system.
➢The application layer programs are based on client and servers.
➢ The Application layer includes the following functions:
❖Identifying communication partners: The application layer identifies the
availability of communication partners for an application with data to transmit.
❖Determining resource availability: The application layer determines whether
sufficient network resources are available for the requested communication.
❖Synchronizing communication: All the communications occur between the
applications requires cooperation which is managed by an application layer.

17. Application Layer
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Services of Application Layers:
The application layer programs are based on client and servers.
➢Network Virtual terminal: An application layer allows a user to log on to a remote host
by creating a software emulation of a terminal at the remote host.
➢File Transfer, Access, and Management (FTAM): An application allows a user to
access files in a remote computer, to retrieve files from a computer and to manage files
in a remote computer.
➢Addressing: To obtain communication between client and server, there is a need for
addressing. To achieve this kind of addressing, DNS is used.
➢Mail Services: An application layer provides Email forwarding and storage.

18. Application Layer
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Application Protocols:
An application layer protocol defines how the application processes running on
different systems, pass the messages to each other.
➢There are several protocols which work for users in Application Layer.
➢Application layer protocols can be broadly divided into two categories:
❖Protocols which are used by users.
oFor email for example, eMail.
❖Protocols which help and support protocols used by users.
oFor example DNS.

19. Application Layer
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Remote Processes Model:
A Remote Processes model is a model in which computers such as servers provide the
network services to the other computers such as clients to perform a user based tasks.
➢Two remote application processes can communicate mainly in two different fashions:
❖Peer-to-peer: Both remote processes are executing at
same level and they exchange data using some shared
resource.
❖Client-Server: One remote process acts as a Client and
requests some resource from another application
process acting as Server.

20. Application Layer
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P2P (peer-to-peer) architecture:
It has no dedicated server in a data center. The peers are the computers which are not
owned by the service provider.
➢The applications based on P2P architecture includes file sharing and internet
telephony.
➢Most of the peers reside in the homes, offices, schools, and universities.
➢Features of P2P architecture
❖Self scalability: In a file sharing system, although each peer generates a workload
by requesting the files, each peer also adds a service capacity by distributing the
files to the peer.
❖Cost-effective: It is cost-effective as it does not require significant server
infrastructure and server bandwidth.

21. Application Layer
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Client Server Model:
A client and server networking model is a model in which computers such as servers
provide the network services to the other computers such as clients to perform a user
based tasks.
➢An application program is known as a client program, running on the local machine
that requests for a service from an application program known as a server program,
running on the remote machine.
➢Two processes in client-server model can interact in various ways:
❖Sockets
❖Remote Procedure Calls (RPC)

22. Application LayerProtocols
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World Wide Web (WWW):
The World Wide Web is abbreviated as WWW and is commonly known as the web. The
WWW was initiated by CERN (European library for Nuclear Research) in 1989.
➢WWW can be defined as the collection of different websites around the world,
containing different information shared via local servers(or computers).
➢Components of the Web: There are 3 components of the web:
❖Uniform Resource Locator (URL): serves as a system for resources on the web.
❖Hyper Text Transfer Protocol (HTTP): specifies communication of browser and
server.
❖Hyper Text Markup Language (HTML): defines the structure, organization and
content of a webpage.

23. Application Layer Protocols
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Hypertext Transfer Protocol:
HTTP provides a standard between a web browser and a web server to establish
communication. It is a set of rules for transferring data from one computer to another.
➢HTTP stands for Hypertext Transfer Protocol and HTTPS is the more secured version
of HTTP,
➢It is a protocol used to access the data on the World Wide Web (www). It can be used
to transfer the data in the form of plain text, hypertext, audio, video, and so on.
❖HTTP is based on the client-server model.
❖It uses TCP for establishing connections.
❖HTTP is a stateless protocol, which means the server doesn’t maintain any
information about the previous request from the client.
❖HTTP uses port number 80 for establishing the connection.

24. Application Layer Protocols
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Uniform Resource Locator (URL):
A client that wants to access the document in an internet needs an address and to
facilitate the access of documents, the HTTP uses the concept of URL.
➢The URL defines four parts: method, host computer, port, and path.
❖Method: The method is the protocol used to retrieve the document from a server. For
example, HTTP.
❖Host: The host is the computer where the information is stored, and the computer is
given an alias name WWW.
❖Port: The URL can also contain the port number of the server, but it's an optional field.
❖Path: Path is the pathname of the file where the information is stored.

25. Application Layer Protocols
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Domain Name System:
The Domain Name System (DNS) works on Client Server model. It uses UDP protocol
for transport layer communication.
➢DNS is a directory service that provides a mapping between the name of a host on the
network and its numerical address.
➢DNS is required for the functioning of the internet.
➢DNS is a service that translates the domain name into IP
addresses.
➢The domain name space is divided into three different
sections: Generic domains, Country domains, and Inverse
domain.

26. Application Layer Protocols
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File transfer protocol:
The Domain Name System (DNS) works on Client Server model. It uses UDP protocol
for transport layer communication.
➢FTP is a standard internet protocol provided by TCP/IP used for transmitting the files
from one host to another.
➢It is mainly used for transferring the web page files from their creator to the computer
that acts as a server for other computers on the internet.
➢Objectives of FTP
❖It provides the sharing of files.
❖It is used to encourage the use of remote computers.
❖It transfers the data more reliably and efficiently.

27. Application Layer Protocols
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File transfer protocol:
FTP protocol overcomes these problems by establishing two connections between hosts.
One connection is used for data transfer, and another connection is used for the
control connection.
➢There are two types of connections in FTP:
❖Control Connection: The control connection uses very
simple rules for communication. interactive FTP
session.
❖Data Connection: The Data Connection uses very
complex rules as data types may vary. The data
connection is made between data transfer processes.

28. Application Layer Protocols
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Electronic Mail:
Electronic mail (e-mail) is a computer-based program that allows users to send and
receive messages like text, voice,video or grapics.
➢Email information is transmitted via email servers and uses a variety of TCP/IP
protocols.
➢For example, the simple mail transfer protocol (SMTP) is a protocol that is used to
send messages. Similarly, IMAP or POP receives messages from a mail server.
➢The following are the essential components of an e-mail system:
❖User Agent (UA)
❖Message Transfer Agent (MTA)
❖Message Access Agent

29. Application Layer Protocols
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Simple Mail Transfer Protocol (SMTP):
SMTP (Simple Mail Transfer Protocol) is an application layer protocol, it is a TCP/IP
protocol used in sending and receiving email.
➢SMTP is a push protocol and is used to send the mail whereas POP (post office
protocol) or IMAP (internet message access protocol) is used to retrieve those emails
at the receiver’s side.
➢The SMTP model is of two types:
❖End-to-end method
❖Store-and-forward method

30. Discussion
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Queries ?
Prof. K. Adisesha
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