Page 18 - CITS - Computer Software Application -TT

COMPUTER SOFTWARE APPLICATION - CITS

The two protocols used in this layer are
1 Transmission Control Protocol (TCP)
TCP is a connection-oriented protocol that offers reliable, ordered, and error-checked data delivery.
2 User Datagram Protocol (UDP)

UDP is a connectionless protocol that provides a lightweight way of sending data between devices without the
overhead of establishing a connection and ensuring reliable delivery.
Some Functions of Transport Layer

• Segmentation and Reassembly - When the transport layer receives a message from the upper layer, it
divides the message into several segments, and each segment is assigned a sequence number that uniquely
identifies each segment. When the message reaches the destination, the transport layer reassembles the
message based on their sequence numbers.
• Service Point Addressing - Computers run many programs simultaneously, so the transfer of data from
source to destination is not only from one computer to another but also from one process to another. The
transport layer adds a header that includes the address known as the service-point address or port address.
The responsibility of the network layer is to transmit data from one computer to another and the responsibility
of the transport layer is to transmit the message to the right process.

5 Session Layer
• The session layer is used to establish, maintain, and synchronous interaction between communicating
devices.
Some Functions of Session Layer

Dialog Controller - The session layer allows the two systems to begin communication with each other in half-
duplex or full-duplex.
Synchronization - The session layer adds some checkpoints when transmitting the data in a sequence. If some
error occurs in the middle of the data transmission, then the transmission will take place again from the checkpoint.
This process is known as synchronization and recovery.
6 Presentation Layer

• A presentation layer is primarily concerned with the syntax and semantics of the information exchanged
between two systems.
• its layer also handles the encryption and decryption that the application layer requires.

• It deals with data format conversion, encryption, and data compression.
Some Functions of Presentation Layer
Data Translation - data format conversions between the sender’s and receiver’s systems For example, it could
translate between ASCII and EBCDIC character encoding.
Encryption/ Decryption - Data encryption translates data into another form or code.
Protocol Use : JPEG, MPEG, GIF
7 Application Layer
• Application layer serves as a window for users and application processes to access network services.

• Web browsers and other internet-connected apps, like file transfer, email, remote access, and more.
• protocols at the application layer, known as HTTP, FTP, SMB/CIFS, TFTP, and SMTP.
Some Functions of Application Layer
File transfer, access, and management (FTAM) - File transfer access and management : This application
allows a user to access file in a remote host, retrieve files in remote host and manage Controlling files from a
remote computer.

5

CITS : IT&ITES - Computer Software Application - Lesson 01-17