what are the function of presentation layer

Layer 6 Presentation Layer

De/Encryption, Encoding, String representation

The presentation layer (data presentation layer, data provision level) sets the system-dependent representation of the data (for example, ASCII, EBCDIC) into an independent form, enabling the syntactically correct data exchange between different systems. Also, functions such as data compression and encryption are guaranteed that data to be sent by the application layer of a system that can be read by the application layer of another system to the layer 6. The presentation layer. If necessary, the presentation layer acts as a translator between different data formats, by making an understandable for both systems data format, the ASN.1 (Abstract Syntax Notation One) used.

OSI Layer 6 - Presentation Layer

The presentation layer is responsible for the delivery and formatting of information to the application layer for further processing or display. It relieves the application layer of concern regarding syntactical differences in data representation within the end-user systems. An example of a presentation service would be the conversion of an EBCDIC-coded text computer file to an ASCII-coded file. The presentation layer is the lowest layer at which application programmers consider data structure and presentation, instead of simply sending data in the form of datagrams or packets between hosts. This layer deals with issues of string representation - whether they use the Pascal method (an integer length field followed by the specified amount of bytes) or the C/C++ method (null-terminated strings, e.g. "thisisastring\0"). The idea is that the application layer should be able to point at the data to be moved, and the presentation layer will deal with the rest. Serialization of complex data structures into flat byte-strings (using mechanisms such as TLV or XML) can be thought of as the key functionality of the presentation layer. Encryption is typically done at this level too, although it can be done on the application, session, transport, or network layers, each having its own advantages and disadvantages. Decryption is also handled at the presentation layer. For example, when logging on to bank account sites the presentation layer will decrypt the data as it is received.[1] Another example is representing structure, which is normally standardized at this level, often by using XML. As well as simple pieces of data, like strings, more complicated things are standardized in this layer. Two common examples are 'objects' in object-oriented programming, and the exact way that streaming video is transmitted. In many widely used applications and protocols, no distinction is made between the presentation and application layers. For example, HyperText Transfer Protocol (HTTP), generally regarded as an application-layer protocol, has presentation-layer aspects such as the ability to identify character encoding for proper conversion, which is then done in the application layer. Within the service layering semantics of the OSI network architecture, the presentation layer responds to service requests from the application layer and issues service requests to the session layer. In the OSI model: the presentation layer ensures the information that the application layer of one system sends out is readable by the application layer of another system. For example, a PC program communicates with another computer, one using extended binary coded decimal interchange code (EBCDIC) and the other using ASCII to represent the same characters. If necessary, the presentation layer might be able to translate between multiple data formats by using a common format. Wikipedia

Data conversion
Character code translation
Compression
Encryption and Decryption

The Presentation OSI Layer is usually composed of 2 sublayers that are:

CASE common application service element

ACSE	Association Control Service Element
ROSE	Remote Operation Service Element
CCR	Commitment Concurrency and Recovery
RTSE	Reliable Transfer Service Element

SASE specific application service element

FTAM	File Transfer, Access and Manager
VT	Virtual Terminal
MOTIS	Message Oriented Text Interchange Standard
CMIP	Common Management Information Protocol
JTM	Job Transfer and Manipulation
MMS	Manufacturing Messaging Service
RDA	Remote Database Access
DTP	Distributed Transaction Processing

Layer 7 Application Layer

Layer 6 presentation layer, layer 5 session layer, layer 4 transport layer, layer 3 network layer, layer 2 data link layer, layer 1 physical layer.

Presentation Layer: Protocols, Examples, Services | Functions of Presentation Layer

Presentation Layer is the 6th layer in the Open System Interconnection (OSI) model where all application programmer consider data structure and presentation, beyond of simply sending the data into form of datagram otherwise packets in between the hosts. Now, we will explain about what is presentation layer with its protocols, example, service ; involving with major functions of presentation Layer with ease. At the end of this article, you will completely educate about What is Presentation Layer in OSI Model without any hassle.

What is Presentation Layer?

Presentation layer is capable to handle abstract data structures, and further it helps to defined and exchange of higher-level data structures.

Presentation Layer Tutorial Headlines:

Let’s get started, functions of presentation layer.

Presentation layer performs various functions in the OSI model ; below explain each one –

Protocols of Presentation Layer

Example of presentation layer protocols:.

Here, we will discuss all examples of presentation layer protocols; below explain each one –

Multipurpose Internet Mail Extensions (MIME) : MIME protocol was introduced by Bell Communications in 1991, and it is an internet standard that provides scalable capable of email for attaching of images, sounds and text in a message.

Network News Transfer Protocol (NNTP) : This protocol is used to make connection with Usenet server and transmit all newsgroup articles in between system over internet.

Apple Filing Protocol (AFP ) : AFP protocol is designed by Apple company for sharing all files over the entire network .

NetWare Core Protocol (NCP) : NCP is a Novell client server model protocol that is designed especially for Local Area Network (LAN). It is capable to perform several functions like as file/print-sharing, clock synchronization, remote processing and messaging.

Network Data Representation (NDR) : NDR is an data encoding standard, and it is implement in the Distributed Computing Environment (DCE).

Tox : The Tox protocol is sometimes regarded as part of both the presentation and application layer , and it is used for sending peer-to-peer instant-messaging as well as video calling.

eXternal Data Representation (XDR) : This protocol provides the description and encoding of entire data, and it’s main goal is to transfer data in between dissimilar computer architecture.

Presentation Layer Services

Design issues with presentation layer, faqs (frequently asked questions), what is meant by presentation layer in osi model.

Presentation Layer is the 6th layer in the Open System Interconnection (OSI) model that is the lowest layer, where all application programmer consider data structure and presentation, beyond of simply sending the data into form of datagram otherwise packets in between the hosts.

What protocols are used in the presentation layer?

Can you explain some presentation layer examples, what are the main functions of the presentation layer, what are services of presentation layer in osi.

Presentation layer has a responsibility for formatting, translation, and delivery of the information for getting to process otherwise display .

Now, i hope that you have completely learnt about what is presentation layer with its protocols, example, service ; involving with major functions of presentation Layer with ease. If this post is useful for you, then please share it along with your friends, family members or relatives over social media platforms like as Facebook, Instagram, Linked In, Twitter, and more.

Also Read: Data Link Layer: Protocols, Examples | Functions of Data Link Layer

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Presentation Layer: What It Is, Design Issues, Functionalities

Description and Functions of Presentation Layer in the OSI model: In this tutorial, we are going to learn what the Presentation layer is and the Functions of the Presentation Layer in the OSI model in Computer Networking. We will also discuss the Design issues with the Presentation Layer and the working of the Presentation Layer with the help of its diagram. By Monika Jha Last updated : May 05, 2023

What is Presentation Layer?

The Presentation Layer is concerned with the syntax and semantics of the information exchanged between two communicating devices.

The presentation layer takes care that the data is sent in that way the receiver of the data will understand the information (data) and will be able to use the data.
Languages that are syntax can be different from the two communicating machines. In this condition, the presentation layer plays the role of translator between them.
It is possible for two machines to communicate with different data representations, data structures to be exchanged can be defined in an abstract way.
These abstract data structures will be managed by the presentation layer and this layer allows higher-level data structures (For example banking records), to be defined and exchanged.

This figure shows the relationship of the presentation layer to the session layer and application layer.

Design Issues with Presentation Layer

The following are the design issues with presentation layer:

To manage and maintain the Syntax and Semantics of the information transmitted.
Encoding data in a standard agreed-upon way just like a string, double, date, etc.
It Performs Standard Encoding scheme on the wire.

Functionalities of the Presentation Layer

Specific functionalities of the presentation layer are as follows:

1. Translation

The processes or running programs in two machines are usually exchanging the information in the form of numbers, character strings and so on before being transmitted. The information should be changed to bitstreams because different computers use different encoding schemes.
The Presentation layer is responsible for compatibility between these encoding methods.
The Presentation layer at the sender's side changes the information from its sender dependent format.
The Presentation layer at the receiving machine changes the common format into its receivers dependent format.

Example: Convert ASCII code to EBCDIC code.

2. Encryption

The system must be able to assure privacy regarding the message or information as it also carries sensitive information.
Encryption means that the sender transforms the original information or message to another form, this data after encryption is known as the ciphertext and this ciphertext sends the resulting message out over the network.
Decryption concerned with the transform of the message back to its original form. This decrypted data is known as plain text.

3. Compression

Data Compression means reduces the number of bits to be transmitted by this reduce the bandwidth of the data.
Data Compression becomes particularly important in the transmission of multimedia such as audio, video, text, etc.

Physical Layer

Data link layer, network layer, routing algorithm, transport layer, application layer, application protocols, network security.

Interview Questions

The presentation layer is the 6 layer from the bottom in the OSI model. This layer presents the incoming data from the application layer of the sender machine to the receiver machine. It converts one format of data to another format of data if both sender and receiver understand different formats; hence this layer is also called the translation layer. It deals with the semantics and syntax of the data, so this layer is also called the syntax layer. It uses operations such as data compression, data encryption & decryption, data conversion, etc.

Data is sent from sender to receiver, but what if the sender device and receiver device understand different formats of code? For example, suppose one device understands ASCII code and another device understands EBCDIC code. In that case, the data must be translated into a code that the recipient understands to determine what data has been sent. The presentation layer is responsible for translating ASCII codes to EBCDIC or vice versa. With the help of the presentation layer, the receiver understands the data effectively and uses it efficiently. Whatever data is being transmitted between the sender and the receiver, that data must be secure because an intruder can hack the data passing between the sender and the receiver. Hackers can modify the data and send the modified data to the receiver to create false communication. The presentation layer is responsible for encrypting and decrypting data to avoid data leakage and data modification.
The plaintext data at the source is encrypted into ciphertext (unreadable format), then it is sent to the receiver, where the ciphertext is decrypted into plaintext. Now, if the hacker tries to hack the data, the hacker receives an encrypted, unreadable form, and if the hacker tries to send modified data, the receiver can detect the modification during decryption; thereby, the data remains safe. If the file size is large, it becomes difficult to transmit the large file over the network. File size can be decreased by compressing the file for easy transmission of data. Compression is the method of diminishing the size of a file to transmit data easily in less time. When the compressed data reaches the receiver, the data is reconstructed back to the original size, and this process is called decompression.

The presentation layer in the OSI model is classified into two sublayers:

This sublayer offers services to layer-7, i.e., the application layer, and requests services from layer-5, i.e., the session layer. It supports various application services, such as Reliable Transfer Service Element (RTSE), Remote Operation Service Element (ROSE), Association Control Service Element (ACSE), and Commitment Concurrency and Recovery (CCR). This sublayer offers application-specific protocols, such as Message Oriented Text Interchange Standard (MOTIS), Remote Database Access (RDA), File Transfer Access and Manager (FTAM), Common Management Information Protocol (CMIP), Virtual Terminal (VT), Distributed Transaction Processing (DTP), Job Transfer and Manipulation (JTM), and others. It is a presentation layer protocol in the OSI model, which was formed by Citrix Systems. It is used for transferring data from server to client. It is a very thin protocol as it does not require much overhead in order to transmit data from the server over to the client. It is well-optimized for the WAN. It is the protocol that is used to implement the presentation layer of the OSI model. It provides different kinds of data representation, such as images, video, audio, numbers, etc. It is used for Microsoft Remote Procedure Call (Microsoft RPC) and Distributed Computing Environment (DCE) / Remote Procedure Calls (RPC). It is a communication protocol that was specifically designed for macOS by Apple, Inc. It provides file services for Classic Mac OS and macOS. This protocol is used to share files over the network. It is a protocol that is associated with the client-server operating system. The user can access the directory, print, message, file, clock synchronization, etc., with the help of this protocol. It supports many platforms, such as Linux, Classic Mac OS, Windows NT, Mac OS X, and Microsoft Windows. It is a telecommunications equipment that splits a stream of data into separate packets and formats packet headers for asynchronous communication on X.25 networks. It receives packets from the network and converts them into a stream of data. The PAD provides many asynchronous terminal connectivities to a host computer. It is a computer network protocol that is used to transfer data between two systems. It was first published in 1987. XDR is used by various systems such as NDMP, Network File System, NetCDF, ZFS, Open Network Computer Remote Procedure Call, and others. It is a protocol that offers ISO presentation services over TCP/IP based networks. This protocol explains an approach to provide stream-line support for OSI over TCP/IP based networks.

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presentation layer

Andrew Froehlich, West Gate Networks

What is the presentation layer?

The presentation layer resides at Layer 6 of the Open Systems Interconnection ( OSI ) communications model and ensures that communications that pass through it are in the appropriate form for the recipient application. In other words, the presentation layer presents the data in a readable format from an application layer perspective.

For example, a presentation layer program could format a file transfer request in binary code to ensure a successful file transfer . Because binary is the most rudimentary of computing languages, it ensures that the receiving device can decipher and translate it into a format the application layer understands and expects.

How the presentation layer works

Once the application layer passes data meant for transport to another device in a certain format, the presentation layer then prepares this data in the most appropriate format the receiving application can understand.

Common data formats include the following:

American Standard Code for Information Interchange and Extended Binary Coded Decimal Interchange Code for text;
JPEG , GIF and TIFF for images; and
MPEG, MIDI and QuickTime for video.

Encryption and decryption of data communications are also performed at the presentation layer. Here, encryption methods and keys exchange between the two communicating devices. Only the sender and receiver can properly encode and decode data so it returns to a readable format.

The presentation layer can serialize -- or translate -- more complex application data objects into a storable and transportable format. This helps to rebuild the object once it arrives at the other side of the communications stream. The presentation layer also deserializes the data stream and places it back into an object format that the application can understand by the application.

Chart depicting the location of the presentation layer within the OSI model.

The tool that manages Hypertext Transfer Protocol ( HTTP ) is an example of a program that loosely adheres to the presentation layer of OSI.

Although it's technically considered an application-layer protocol per the TCP/IP model , HTTP includes presentation layer services within it. HTTP works when the requesting device forwards user requests passed to the web browser onto a web server elsewhere in the network.

HTTP receives a return message from the web server that includes a Multipurpose Internet Mail Extensions ( MIME ) header. The MIME header indicates the type of file -- text, video, or audio -- that has been received so that an appropriate player utility can present the file to the user.

Functions of the presentation layer

ensures proper formatting and delivery to and from the application layer;
performs data encryption; and
manages serialization of data objects.

Editor's note: This article was republished in January 2023 to improve the reader experience.

Continue Reading About presentation layer

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Presentation layer in osi model.

Last Updated on March 7, 2024 by Abhishek Sharma

The OSI (Open Systems Interconnection) model is a conceptual framework used to understand the functions of a telecommunication or computing system. It consists of seven layers, each responsible for specific tasks. The sixth layer, known as the Presentation Layer, plays a crucial role in ensuring that data exchanged between systems is readable and usable. Let’s explore the functions and importance of the Presentation Layer in the OSI model.

What is Presentation Layer in OSI Model?

The Presentation Layer, the sixth layer of the OSI (Open Systems Interconnection) model, is responsible for ensuring that data exchanged between systems is in a format that can be interpreted and used by the receiving system. It performs various functions, including data translation, encryption, compression, and formatting, to facilitate efficient and secure communication between networked devices.

Functions of the Presentation Layer

Below are some of the functions of the Presentation Layer in OSI Model:

Data Translation: The Presentation Layer translates data from the format used by the application layer into a format that can be transmitted over the network. This includes encoding, compression, and encryption.
Data Formatting: It ensures that data is formatted according to the specifications of the application layer. This includes converting between different character sets, such as ASCII and Unicode.
Data Compression: The Presentation Layer compresses data to reduce the amount of bandwidth required for transmission, improving network efficiency.
Data Encryption: It encrypts data to ensure that it remains secure during transmission, protecting it from unauthorized access.
Data Syntax: The Presentation Layer defines the syntax for data representation, ensuring that both the sender and receiver understand the structure of the data being exchanged.

Importance of the Presentation Layer

Importance of Presentation Layer are:

Data Integrity: By ensuring that data is formatted correctly and encrypted, the Presentation Layer helps maintain the integrity of data during transmission.
Interoperability: The Presentation Layer enables different systems to communicate with each other by ensuring that data is translated into a common format that both systems understand.
Efficiency: Data compression reduces the amount of data that needs to be transmitted, improving network efficiency and reducing bandwidth requirements.
Security: Encryption provided by the Presentation Layer ensures that data remains secure and protected from unauthorized access.

Conclusion The Presentation Layer is a crucial component of the OSI model, responsible for ensuring that data exchanged between systems is in a format that can be understood and used. By performing functions such as data translation, formatting, compression, and encryption, the Presentation Layer plays a vital role in maintaining data integrity, facilitating interoperability, and ensuring the security of data during transmission.

FAQs related to Presentation Layer in OSI Model

Here are some of the FAQs related to Presentation Layer in OSI Model:

Q1: What is the role of the Presentation Layer in the OSI model? The Presentation Layer ensures that data exchanged between systems is in a usable format, performing functions such as data translation, encryption, compression, and formatting.

Q2: How does the Presentation Layer ensure data security? The Presentation Layer encrypts data before transmission, making it unreadable to unauthorized parties, thus ensuring data security.

Q3: Why is data compression important in the Presentation Layer? Data compression reduces the size of data packets, leading to faster transmission speeds and optimized bandwidth usage, which is crucial in high-traffic networks.

Q4: How does the Presentation Layer facilitate interoperability between systems? By translating data into a common format that both sender and receiver understand, the Presentation Layer enables different systems to communicate with each other seamlessly.

Q5: Can the Presentation Layer be bypassed in data transmission? While it is possible to bypass the Presentation Layer in some cases, doing so can lead to compatibility issues between systems and is not recommended.

Presentation layer and Session layer of the OSI model

There are two popular networking models: the OSI layers model and the TCP/IP layers model. The presentation layer and session layer exist only in the OSI layers models. The TCP/IP layers model merges them into the application layer.

The Presentation Layer

The presentation layer is the sixth layer of the OSI Reference model. It defines how data and information is transmitted and presented to the user. It translates data and format code in such a way that it is correctly used by the application layer.

It identifies the syntaxes that different applications use and formats data using those syntaxes. For example, a web browser receives a web page from a web server in the HTML language. HTML language includes many tags and markup that have no meaning for the end user but they have special meaning for the web browser. the web browser uses the presentation layer's logic to read those syntaxes and format data in such a way the web server wants it to be present to the user.

On the sender device, it encapsulates and compresses data before sending it to the network to increase the speed and security of the network. On the receiver device, it de-encapsulates and decompresses data before presenting it to the user.

Examples of the presentation layer

Example standards for representing graphical information: JPEG, GIF, JPEG, and TIFF.

Example standards for representing audio information: WAV, MIDI, MP3.

Example standards for representing video information: WMV, MOV, MP4, MPEG.

Example standards for representing text information: doc, xls, txt, pdf.

Functions of the presentation layer

It formats and presents data and information.
It encrypts and compresses data before giving it to the session layer.
It de-encrypts and decompresses the encrypted and compressed data it receives from the session layer.

Session layer

The session layer is the fifth layer of the OSI layers model. It is responsible for initiating, establishing, managing, and terminating sessions between the local application and the remote applications.

It defines standards for three modes of communication: full duplex, half-duplex, and simplex.

In the full duplex mode, both devices can send and receive data simultaneously. The internet connection is an example of the full duplex mode.

In the half duplex mode, only one device can send data at a time. A telephone conversation is an example of the half-duplex mode.

In the simplex mode, only one device can send data. A radio broadcast is an example of the simplex mode.

Functions of the session layer

It is responsible for terminating sessions, creating checkpoints, and recovering data when sessions are interrupted.
It opens and maintains logical communication channels between network applications running on the local host and network applications running on the remote host.
If a network application uses an authentication mechanism before it opens a logical communication channel (session) with the remote host, it handles the authentication process.

Examples of the session layer

Structure Query Language (SQL), Remote Procedure Call (RPC), and Network File System (NFS) are examples of the session layer.

By ComputerNetworkingNotes Updated on 2023-04-25

ComputerNetworkingNotes CCNA Study Guide Presentation layer and Session layer of the OSI model

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What is the OSI model? How to explain and remember its 7 layers

A tutorial on the open systems interconnection (osi) networking reference model plus tips on how to memorize the seven layers..

AI image 7 layers of OSI model telecommunications network

The Open Systems Interconnect (OSI) model is a conceptual framework that describes networking or telecommunications systems as seven layers, each with its own function.

The layers help network pros visualize what is going on within their networks and can help network managers narrow down problems (is it a physical issue or something with the application?), as well as computer programmers (when developing an application, which other layers does it need to work with?). Tech vendors selling new products will often refer to the OSI model to help customers understand which layer their products work with or whether it works “across the stack”.

The 7 layers of the OSI model

The layers (from bottom to top) are: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

It wasn’t always this way. Conceived in the 1970s when computer networking was taking off, two separate models were merged in 1983 and published in 1984 to create the OSI model that most people are familiar with today. Most descriptions of the OSI model go from top to bottom, with the numbers going from Layer 7 down to Layer 1.

The layers, and what they represent, are as follows:

Layer 7: Application

The Application Layer in the OSI model is the layer that is the “closest to the end user”. It receives information directly from users and displays incoming data to the user. Oddly enough, applications themselves do not reside at the application layer. Instead the layer facilitates communication through lower layers in order to establish connections with applications at the other end. Web browsers (Google Chrome, Firefox, Safari, etc.) TelNet, and FTP, are examples of communications that rely on Layer 7.

Layer 6: Presentation

The Presentation Layer represents the area that is independent of data representation at the application layer. In general, it represents the preparation or translation of application format to network format, or from network formatting to application format. In other words, the layer “presents” data for the application or the network. A good example of this is encryption and decryption of data for secure transmission; this happens at Layer 6.

Layer 5: Session

When two computers or other networked devices need to speak with one another, a session needs to be created, and this is done at the Session Layer . Functions at this layer involve setup, coordination (how long should a system wait for a response, for example) and termination between the applications at each end of the session.

Layer 4: Transport

The Transport Layer deals with the coordination of the data transfer between end systems and hosts. How much data to send, at what rate, where it goes, etc. The best known example of the Transport Layer is the Transmission Control Protocol (TCP), which is built on top of the Internet Protocol (IP), commonly known as TCP/IP. TCP and UDP port numbers work at Layer 4, while IP addresses work at Layer 3, the Network Layer.

Layer 3: Network

Here at the Network Layer is where you’ll find most of the router functionality that most networking professionals care about and love. In its most basic sense, this layer is responsible for packet forwarding, including routing through different routers . You might know that your Boston computer wants to connect to a server in California, but there are millions of different paths to take. Routers at this layer help do this efficiently.

Layer 2: Data Link

The Data Link Layer provides node-to-node data transfer (between two directly connected nodes), and also handles error correction from the physical layer. Two sublayers exist here as well–the Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. In the networking world, most switches operate at Layer 2. But it’s not that simple. Some switches also operate at Layer 3 in order to support virtual LANs that may span more than one switch subnet, which requires routing capabilities.

Layer 1: Physical

At the bottom of our OSI model we have the Physical Layer, which represents the electrical and physical representation of the system. This can include everything from the cable type, radio frequency link (as in a Wi-Fi network), as well as the layout of pins, voltages, and other physical requirements. When a networking problem occurs, many networking pros go right to the physical layer to check that all of the cables are properly connected and that the power plug hasn’t been pulled from the router, switch or computer, for example.

Why you need to know the 7 OSI layers

Most people in IT will likely need to know about the different layers when they’re going for their certifications, much like a civics student needs to learn about the three branches of the US government. After that, you hear about the OSI model when vendors are making pitches about which layers their products work with.

In a Quora post asking about the purpose of the OSI model, Vikram Kumar answered this way: “The purpose of the OSI reference model is to guide vendors and developers so the digital communication products and software programs they create will interoperate, and to facilitate clear comparisons among communications tools.”

While some people may argue that the OSI model is obsolete (due to its conceptual nature) and less important than the four layers of the TCP/IP model, Kumar says that “it is difficult to read about networking technology today without seeing references to the OSI model and its layers, because the model’s structure helps to frame discussions of protocols and contrast various technologies.”

If you can understand the OSI model and its layers, you can also then understand which protocols and devices can interoperate with each other when new technologies are developed and explained.

The OSI model remains relevant

In a post on GeeksforGeeks, contributor Vabhav Bilotia argues several reasons why the OSI model remains relevant, especially when it comes to security and determining where technical risks and vulnerabilities may exist.

For example, by understanding the different layers, enterprise security teams can identify and classify physical access, where the data is sitting, and provide an inventory of the applications that employees use to access data and resources.

“Knowing where the majority of your company’s data is held, whether on-premises or in cloud services, will help define your information security policy,” writes Bilotia. “You can invest in the correct solutions that provide you data visibility within the proper OSI layers once you have this knowledge.”

In addition, the OSI model can be used to understand cloud infrastructure migrations, particularly when it comes to securing data within the cloud.

And because the model has been around for so long and understood by so many, the uniform vocabulary and terms helps networking professionals understand quickly about the components of the networking system “While this paradigm is not directly implemented in today’s TCP/IP networks, it is a useful conceptual model for relating multiple technologies to one another and implementing the appropriate technology in the appropriate way,” Bilotia writes. We couldn’t agree more.

How to remember the OSI Model 7 layers: 8 mnemonic tricks

If you need to memorize the layers for a college or certification test, here are a few sentences to help remember them in order. The first letter of each word is the same as the first letter an OSI layer.

From Application to Physical (Layer 7 to Layer 1):

All People Seem To Need Data Processing
All Pros Search Top Notch Donut Places
A Penguin Said That Nobody Drinks Pepsi
A Priest Saw Two Nuns Doing Pushups

From Physical to Application (Layer 1 to Layer 7):

Please Do Not Throw Sausage Pizza Away
Pew! Dead Ninja Turtles Smell Particularly Awful
People Don’t Need To See Paula Abdul
Pete Doesn’t Need To Sell Pickles Anymore

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The Presentation Layer of OSI Model

The presentation layer (Layer 6) ensures that the message is presented to the upper layer in a standardized format. It deals with the syntax and the semantics of the messages.

The main functions of the presentation layer are as follows −

It encodes the messages from the user dependent format to the common format and vice versa, for communication among dissimilar systems.
It is responsible for data encryption and decryption of sensitive data before they are transmitted over common channels.
It is also responsible for data compression. Data compression is done at the source to reduce the number of bits to be transmitted. It reduces the storage space and increases the file transfer rate. It is particularly useful for transmission of large multimedia files.

Related Articles
The Transport Layer of OSI Model
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The Data Link Layer of OSI Model
Explain the functions of Presentation Layer.
What is Presentation Layer?
The OSI Reference Model
What is a presentation layer?
Advantages and Disadvantages of the OSI Model
Computer Networks – Layers of OSI Model
What is the OSI Reference Model?
OSI Model in Computer Networking
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Presentation Layer of OSI Model (Layer-6)

Presentation Layer is responsible for representation & formatting of data for session Layer in encapsulation process. It is the 6th Layer in the seven layer OSI Model after Session Layer. Presentation layer serves like a translator & takes care that the data is sent in such a way that the receiver will understand the information or data and will be able to use the data. OSI Model divides the network communication processes into seven layers in order to simplify it. Each layer performs specific functions to support the layers above it. This seven Layer model starts from Physical till Application Layer & Presentation Layer is on 2nd place in this model as in below figure:

Functions/Duties of Presentation Layer

Each Layer in OSI Model Performs some important duties. Important functions performed by Presentation Layer are listed here:

The first & most important is, of course Data Formatting & Representation . When the presentation layer receives data from the application layer, to be sent over the network, it makes sure that the data is in the proper format. If it is not, the presentation layer converts the data to the proper format. On the other side of communication, when the presentation layer receives network data from the Presentation layer, it makes sure that the data is in the proper format and once again converts it if it is not.
It is also responsible for Data Encryption/Decryption: Presentation Layer carries out encryption at the transmitter end and decryption at the receiver end to keep data secure during transmission.
Data Compression/De-compression also falls under the responsibility matrix of Presentation Layer . Presentation Layer compresses data to a small size to reduce resource usage such as data storage space or transmission capacity.

*Encryption is typically done at this layer as well, although it can be done on the application, session, transport, or network layers, each having its own advantages and disadvantages

Presentation Layer Protocols

The OSI Model provides a conceptual framework for communication between computers, but the model itself is not a method of communication. Actual communication is made possible by using communication protocols. Each layer on the OSI Model has some protocols associated with it. Some important protocols on Presentation layer are listed in below:

JPEG/GIF/PNG/TIFF

Network Equipment/Components at Presentation Layer

Load Balancers
End Devices e.g. Computers, Smart Phones, Servers, …

Presentation Layer is the 6th Layer in seven Layer OSI Model. It performs important functions like Data Formatting, Data Representation, Data Encryption/Decryption, Data Compression and De-compression. Important Protocols at Presentation Layer include ASCII, EBCDIC, JPEG, MPEG, GIF, PNG, TIFF, SSL & TLS. Equipment operating at Presentation Layer include Firewalls, Gateways, Load Balancers & Computers.

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OSI model - What's the presentation and session layer for?

So I feel I pretty well understand the application layer, and everything below (and including) the transport layer.

The session and presentation layers, though, I don't fully understand. I've read the simplistic descriptions in Wikipedia, but it doesn't have an example of why separating out those layers is useful.

What is the session layer? What does it do, and under what circumstances is it better to have a session layer than simply talk to the transport with your app?
What is the presentation layer? (same questions as above)

7 Answers 7

The session layer is meant to store states between two connections, like what we use cookies for when working with web programming.

The presentation layer is meant to convert between different formats. This was simpler when the only format that was worried about was character encoding, ie ASCII and EBCDIC. When you consider all of the different formats that we have today(Quicktime, Flash, Pdf) centralizing this layer is out of the question.

TCP/IP doesn't make any allocation to these layers, since they are really out of the scope of a networking protocol. It's up to the applications that take advantage of the stack to implement these.

The reasons there aren't any examples on wikipedia is that there aren't a whole lot of examples of the OSI network model, period.

OSI has once again created a standard nobody uses, so nobody really know how one should use it.

Layers 5-6 are not commonly used in today's web applications, so you don't hear much about them. The TCP/IP stack is slightly different than a pure OSI Model.

One of the reasons TCP/IP is used today instead of OSI is it was too bloated and theoretical, the session and presentation layer aren't really needed as separate layers as it turned out.

I think that presentation layer protocols define the format of data. This means protocols like XML or ASN.1. You could argue that video/audio codecs are part of the presentation layer Although this is probably heading towards the application layer.

I can't help you with the session layer. That has always baffled me.

To be honest, there are very vague boundaries in everything above the transport layer. This is because it is usually handled by a single software application. Also, these layers are not directly associated with transporting data from A to B. Layers 4 and below each have a very specific purpose in moving the data e.g. switching, routing, ensuring data integrity etc. This makes it easier to distinguish between these layers.

Presentation Layer The Presentation Layer represents the area that is independent of data representation at the application layer - in general, it represents the preparation or translation of application format to network format, or from network formatting to application format. In other words, the layer “presents” data for the application or the network. A good example of this is encryption and decryption of data for secure transmission - this happens at Layer 6.

Session Layer When two devices, computers or servers need to “speak” with one another, a session needs to be created, and this is done at the Session Layer. Functions at this layer involve setup, coordination (how long should a system wait for a response, for example) and termination between the applications at each end of the session.

For the presentation layer :because most of communication done between heterogeneous systems (Operating Systems,programing langages,cpu architectures)we need to use a unified idepedent specification .like ANS1 ans BRE.

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The OSI Model – The 7 Layers of Networking Explained in Plain English

This article explains the Open Systems Interconnection (OSI) model and the 7 layers of networking, in plain English.

The OSI model is a conceptual framework that is used to describe how a network functions. In plain English, the OSI model helped standardize the way computer systems send information to each other.

Learning networking is a bit like learning a language - there are lots of standards and then some exceptions. Therefore, it’s important to really understand that the OSI model is not a set of rules. It is a tool for understanding how networks function.

Once you learn the OSI model, you will be able to further understand and appreciate this glorious entity we call the Internet, as well as be able to troubleshoot networking issues with greater fluency and ease.

All hail the Internet!

Prerequisites

You don’t need any prior programming or networking experience to understand this article. However, you will need:

Basic familiarity with common networking terms (explained below)
A curiosity about how things work :)

Learning Objectives

Over the course of this article, you will learn:

What the OSI model is
The purpose of each of the 7 layers
The problems that can happen at each of the 7 layers
The difference between TCP/IP model and the OSI model

Common Networking Terms

Here are some common networking terms that you should be familiar with to get the most out of this article. I’ll use these terms when I talk about OSI layers next.

A node is a physical electronic device hooked up to a network, for example a computer, printer, router, and so on. If set up properly, a node is capable of sending and/or receiving information over a network.

Nodes may be set up adjacent to one other, wherein Node A can connect directly to Node B, or there may be an intermediate node, like a switch or a router, set up between Node A and Node B.

Typically, routers connect networks to the Internet and switches operate within a network to facilitate intra-network communication. Learn more about hub vs. switch vs. router.

Here's an example:

For the nitpicky among us (yep, I see you), host is another term that you will encounter in networking. I will define a host as a type of node that requires an IP address. All hosts are nodes, but not all nodes are hosts. Please Tweet angrily at me if you disagree.

Links connect nodes on a network. Links can be wired, like Ethernet, or cable-free, like WiFi.

Links to can either be point-to-point, where Node A is connected to Node B, or multipoint, where Node A is connected to Node B and Node C.

When we’re talking about information being transmitted, this may also be described as a one-to-one vs. a one-to-many relationship.

A protocol is a mutually agreed upon set of rules that allows two nodes on a network to exchange data.

“A protocol defines the rules governing the syntax (what can be communicated), semantics (how it can be communicated), and synchronization (when and at what speed it can be communicated) of the communications procedure. Protocols can be implemented on hardware, software, or a combination of both. Protocols can be created by anyone, but the most widely adopted protocols are based on standards.” - The Illustrated Network.

Both wired and cable-free links can have protocols.

While anyone can create a protocol, the most widely adopted protocols are often based on standards published by Internet organizations such as the Internet Engineering Task Force (IETF).

A network is a general term for a group of computers, printers, or any other device that wants to share data.

Network types include LAN, HAN, CAN, MAN, WAN, BAN, or VPN. Think I’m just randomly rhyming things with the word can ? I can ’t say I am - these are all real network types. Learn more here .

Topology describes how nodes and links fit together in a network configuration, often depicted in a diagram. Here are some common network topology types:

What is Network Topology? Best Guides to Types & Diagrams - DNSstuff

A network consists of nodes, links between nodes, and protocols that govern data transmission between nodes.

At whatever scale and complexity networks get to, you will understand what’s happening in all computer networks by learning the OSI model and 7 layers of networking.

What is the OSI Model?

The OSI model consists of 7 layers of networking.

First, what’s a layer?

No, a layer - not a lair . Here there are no dragons.

A layer is a way of categorizing and grouping functionality and behavior on and of a network.

In the OSI model, layers are organized from the most tangible and most physical, to less tangible and less physical but closer to the end user.

Each layer abstracts lower level functionality away until by the time you get to the highest layer. All the details and inner workings of all the other layers are hidden from the end user.

How to remember all the names of the layers? Easy.

Please | Physical Layer
Do | Data Link Layer
Not | Network Layer
Tell (the) | Transport Layer
Secret | Session Layer
Password (to) | Presentation Layer
Anyone | Application Layer

Keep in mind that while certain technologies, like protocols, may logically “belong to” one layer more than another, not all technologies fit neatly into a single layer in the OSI model. For example, Ethernet, 802.11 (Wifi) and the Address Resolution Protocol (ARP) procedure operate on >1 layer.

The OSI is a model and a tool, not a set of rules.

OSI Layer 1

Layer 1 is the physical layer . There’s a lot of technology in Layer 1 - everything from physical network devices, cabling, to how the cables hook up to the devices. Plus if we don’t need cables, what the signal type and transmission methods are (for example, wireless broadband).

Instead of listing every type of technology in Layer 1, I’ve created broader categories for these technologies. I encourage readers to learn more about each of these categories:

Nodes (devices) and networking hardware components. Devices include hubs, repeaters, routers, computers, printers, and so on. Hardware components that live inside of these devices include antennas, amplifiers, Network Interface Cards (NICs), and more.
Device interface mechanics. How and where does a cable connect to a device (cable connector and device socket)? What is the size and shape of the connector, and how many pins does it have? What dictates when a pin is active or inactive?
Functional and procedural logic. What is the function of each pin in the connector - send or receive? What procedural logic dictates the sequence of events so a node can start to communicate with another node on Layer 2?
Cabling protocols and specifications. Ethernet (CAT), USB, Digital Subscriber Line (DSL) , and more. Specifications include maximum cable length, modulation techniques, radio specifications, line coding, and bits synchronization (more on that below).
Cable types. Options include shielded or unshielded twisted pair, untwisted pair, coaxial and so on. Learn more about cable types here .
Signal type. Baseband is a single bit stream at a time, like a railway track - one-way only. Broadband consists of multiple bit streams at the same time, like a bi-directional highway.
Signal transmission method (may be wired or cable-free). Options include electrical (Ethernet), light (optical networks, fiber optics), radio waves (802.11 WiFi, a/b/g/n/ac/ax variants or Bluetooth). If cable-free, then also consider frequency: 2.5 GHz vs. 5 GHz. If it’s cabled, consider voltage. If cabled and Ethernet, also consider networking standards like 100BASE-T and related standards.

The data unit on Layer 1 is the bit.

A bit the smallest unit of transmittable digital information. Bits are binary, so either a 0 or a 1. Bytes, consisting of 8 bits, are used to represent single characters, like a letter, numeral, or symbol.

Bits are sent to and from hardware devices in accordance with the supported data rate (transmission rate, in number of bits per second or millisecond) and are synchronized so the number of bits sent and received per unit of time remains consistent (this is called bit synchronization). The way bits are transmitted depends on the signal transmission method.

Nodes can send, receive, or send and receive bits. If they can only do one, then the node uses a simplex mode. If they can do both, then the node uses a duplex mode. If a node can send and receive at the same time, it’s full-duplex – if not, it’s just half-duplex.

The original Ethernet was half-duplex. Full-duplex Ethernet is an option now, given the right equipment.

How to Troubleshoot OSI Layer 1 Problems

Here are some Layer 1 problems to watch out for:

Defunct cables, for example damaged wires or broken connectors
Broken hardware network devices, for example damaged circuits
Stuff being unplugged (...we’ve all been there)

If there are issues in Layer 1, anything beyond Layer 1 will not function properly.

Layer 1 contains the infrastructure that makes communication on networks possible.

It defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating physical links between network devices. - Source

Fun fact: deep-sea communications cables transmit data around the world. This map will blow your mind: https://www.submarinecablemap.com/

And because you made it this far, here’s a koala:

OSI Layer 2

Layer 2 is the data link layer . Layer 2 defines how data is formatted for transmission, how much data can flow between nodes, for how long, and what to do when errors are detected in this flow.

In more official tech terms:

Line discipline. Who should talk for how long? How long should nodes be able to transit information for?
Flow control. How much data should be transmitted?
Error control - detection and correction . All data transmission methods have potential for errors, from electrical spikes to dirty connectors. Once Layer 2 technologies tell network administrators about an issue on Layer 2 or Layer 1, the system administrator can correct for those errors on subsequent layers. Layer 2 is mostly concerned with error detection, not error correction. ( Source )

There are two distinct sublayers within Layer 2:

Media Access Control (MAC): the MAC sublayer handles the assignment of a hardware identification number, called a MAC address, that uniquely identifies each device on a network. No two devices should have the same MAC address. The MAC address is assigned at the point of manufacturing. It is automatically recognized by most networks. MAC addresses live on Network Interface Cards (NICs). Switches keep track of all MAC addresses on a network. Learn more about MAC addresses on PC Mag and in this article . Learn more about network switches here .
Logical Link Control (LLC): the LLC sublayer handles framing addressing and flow control. The speed depends on the link between nodes, for example Ethernet or Wifi.

The data unit on Layer 2 is a frame .

Each frame contains a frame header, body, and a frame trailer:

Header: typically includes MAC addresses for the source and destination nodes.
Body: consists of the bits being transmitted.
Trailer: includes error detection information. When errors are detected, and depending on the implementation or configuration of a network or protocol, frames may be discarded or the error may be reported up to higher layers for further error correction. Examples of error detection mechanisms: Cyclic Redundancy Check (CRC) and Frame Check Sequence (FCS). Learn more about error detection techniques here .

Example of frames, the network layer, and the physical layer

Typically there is a maximum frame size limit, called an Maximum Transmission Unit, MTU. Jumbo frames exceed the standard MTU, learn more about jumbo frames here .

How to Troubleshoot OSI Layer 2 Problems

Here are some Layer 2 problems to watch out for:

All the problems that can occur on Layer 1
Unsuccessful connections (sessions) between two nodes
Sessions that are successfully established but intermittently fail
Frame collisions

The Data Link Layer allows nodes to communicate with each other within a local area network. The foundations of line discipline, flow control, and error control are established in this layer.

OSI Layer 3

Layer 3 is the network layer . This is where we send information between and across networks through the use of routers. Instead of just node-to-node communication, we can now do network-to-network communication.

Routers are the workhorse of Layer 3 - we couldn’t have Layer 3 without them. They move data packets across multiple networks.

Not only do they connect to Internet Service Providers (ISPs) to provide access to the Internet, they also keep track of what’s on its network (remember that switches keep track of all MAC addresses on a network), what other networks it’s connected to, and the different paths for routing data packets across these networks.

Routers store all of this addressing and routing information in routing tables.

Here’s a simple example of a routing table:

A routing table showing the destination, subnet mask, and interface

The data unit on Layer 3 is the data packet . Typically, each data packet contains a frame plus an IP address information wrapper. In other words, frames are encapsulated by Layer 3 addressing information.

The data being transmitted in a packet is also sometimes called the payload . While each packet has everything it needs to get to its destination, whether or not it makes it there is another story.

Layer 3 transmissions are connectionless, or best effort - they don't do anything but send the traffic where it’s supposed to go. More on data transport protocols on Layer 4.

Once a node is connected to the Internet, it is assigned an Internet Protocol (IP) address, which looks either like 172.16. 254.1 (IPv4 address convention) or like 2001:0db8:85a3:0000:0000:8a2e:0370:7334 (IPv6 address convention). Routers use IP addresses in their routing tables.

IP addresses are associated with the physical node’s MAC address via the Address Resolution Protocol (ARP), which resolves MAC addresses with the node’s corresponding IP address.

ARP is conventionally considered part of Layer 2, but since IP addresses don’t exist until Layer 3, it’s also part of Layer 3.

How to Troubleshoot OSI Layer 3 Problems

Here are some Layer 3 problems to watch out for:

All the problems that can crop up on previous layers :)
Faulty or non-functional router or other node
IP address is incorrectly configured

Many answers to Layer 3 questions will require the use of command-line tools like ping , trace , show ip route , or show ip protocols . Learn more about troubleshooting on layer 1-3 here .

The Network Layer allows nodes to connect to the Internet and send information across different networks.

OSI Layer 4

Layer 4 is the transport layer . This where we dive into the nitty gritty specifics of the connection between two nodes and how information is transmitted between them. It builds on the functions of Layer 2 - line discipline, flow control, and error control.

This layer is also responsible for data packet segmentation, or how data packets are broken up and sent over the network.

Unlike the previous layer, Layer 4 also has an understanding of the whole message, not just the contents of each individual data packet. With this understanding, Layer 4 is able to manage network congestion by not sending all the packets at once.

The data units of Layer 4 go by a few names. For TCP, the data unit is a packet. For UDP, a packet is referred to as a datagram. I’ll just use the term data packet here for the sake of simplicity.

Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are two of the most well-known protocols in Layer 4.

TCP, a connection-oriented protocol, prioritizes data quality over speed.

TCP explicitly establishes a connection with the destination node and requires a handshake between the source and destination nodes when data is transmitted. The handshake confirms that data was received. If the destination node does not receive all of the data, TCP will ask for a retry.

TCP also ensures that packets are delivered or reassembled in the correct order. Learn more about TCP here .

UDP, a connectionless protocol, prioritizes speed over data quality. UDP does not require a handshake, which is why it’s called connectionless.

Because UDP doesn’t have to wait for this acknowledgement, it can send data at a faster rate, but not all of the data may be successfully transmitted and we’d never know.

If information is split up into multiple datagrams, unless those datagrams contain a sequence number, UDP does not ensure that packets are reassembled in the correct order. Learn more about UDP here .

TCP and UDP both send data to specific ports on a network device, which has an IP address. The combination of the IP address and the port number is called a socket.

Learn more about sockets here .

Learn more about the differences and similarities between these two protocols here .

How to Troubleshoot OSI Layer 4 Problems

Here are some Layer 4 problems to watch out for:

Blocked ports - check your Access Control Lists (ACL) & firewalls
Quality of Service (QoS) settings. QoS is a feature of routers/switches that can prioritize traffic, and they can really muck things up. Learn more about QoS here .

The Transport Layer provides end-to-end transmission of a message by segmenting a message into multiple data packets; the layer supports connection-oriented and connectionless communication.

OSI Layer 5

Layer 5 is the session layer . This layer establishes, maintains, and terminates sessions.

A session is a mutually agreed upon connection that is established between two network applications. Not two nodes! Nope, we’ve moved on from nodes. They were so Layer 4.

Just kidding, we still have nodes, but Layer 5 doesn’t need to retain the concept of a node because that’s been abstracted out (taken care of) by previous layers.

So a session is a connection that is established between two specific end-user applications. There are two important concepts to consider here:

Client and server model: the application requesting the information is called the client, and the application that has the requested information is called the server.
Request and response model: while a session is being established and during a session, there is a constant back-and-forth of requests for information and responses containing that information or “hey, I don’t have what you’re requesting.”

Sessions may be open for a very short amount of time or a long amount of time. They may fail sometimes, too.

Depending on the protocol in question, various failure resolution processes may kick in. Depending on the applications/protocols/hardware in use, sessions may support simplex, half-duplex, or full-duplex modes.

Examples of protocols on Layer 5 include Network Basic Input Output System (NetBIOS) and Remote Procedure Call Protocol (RPC), and many others.

From here on out (layer 5 and up), networks are focused on ways of making connections to end-user applications and displaying data to the user.

How to Troubleshoot OSI Layer 5 Problems

Here are some Layer 5 problems to watch out for:

Servers are unavailable
Servers are incorrectly configured, for example Apache or PHP configs
Session failure - disconnect, timeout, and so on.

The Session Layer initiates, maintains, and terminates connections between two end-user applications. It responds to requests from the presentation layer and issues requests to the transport layer.

OSI Layer 6

Layer 6 is the presentation layer . This layer is responsible for data formatting, such as character encoding and conversions, and data encryption.

The operating system that hosts the end-user application is typically involved in Layer 6 processes. This functionality is not always implemented in a network protocol.

Layer 6 makes sure that end-user applications operating on Layer 7 can successfully consume data and, of course, eventually display it.

There are three data formatting methods to be aware of:

American Standard Code for Information Interchange (ASCII): this 7-bit encoding technique is the most widely used standard for character encoding. One superset is ISO-8859-1, which provides most of the characters necessary for languages spoken in Western Europe.
Extended Binary-Coded Decimal Interchange Code (EBDCIC): designed by IBM for mainframe usage. This encoding is incompatible with other character encoding methods.
Unicode: character encodings can be done with 32-, 16-, or 8-bit characters and attempts to accommodate every known, written alphabet.

Learn more about character encoding methods in this article , and also here .

Encryption: SSL or TLS encryption protocols live on Layer 6. These encryption protocols help ensure that transmitted data is less vulnerable to malicious actors by providing authentication and data encryption for nodes operating on a network. TLS is the successor to SSL.

How to Troubleshoot OSI Layer 6 Problems

Here are some Layer 6 problems to watch out for:

Non-existent or corrupted drivers
Incorrect OS user access level

The Presentation Layer formats and encrypts data.

OSI Layer 7

Layer 7 is the application layer .

True to its name, this is the layer that is ultimately responsible for supporting services used by end-user applications. Applications include software programs that are installed on the operating system, like Internet browsers (for example, Firefox) or word processing programs (for example, Microsoft Word).

Applications can perform specialized network functions under the hood and require specialized services that fall under the umbrella of Layer 7.

Electronic mail programs, for example, are specifically created to run over a network and utilize networking functionality, such as email protocols, which fall under Layer 7.

Applications will also control end-user interaction, such as security checks (for example, MFA), identification of two participants, initiation of an exchange of information, and so on.

Protocols that operate on this level include File Transfer Protocol (FTP), Secure Shell (SSH), Simple Mail Transfer Protocol (SMTP), Internet Message Access Protocol (IMAP), Domain Name Service (DNS), and Hypertext Transfer Protocol (HTTP).

While each of these protocols serve different functions and operate differently, on a high level they all facilitate the communication of information. ( Source )

How to Troubleshoot OSI Layer 7 Problems

Here are some Layer 7 problems to watch out for:

All issues on previous layers
Incorrectly configured software applications
User error (... we’ve all been there)

The Application Layer owns the services and functions that end-user applications need to work. It does not include the applications themselves.

Our Layer 1 koala is all grown up.

Learning check - can you apply makeup to a koala?

Don’t have a koala?

Well - answer these questions instead. It’s the next best thing, I promise.

What is the OSI model?
What are each of the layers?
How could I use this information to troubleshoot networking issues?

Congratulations - you’ve taken one step farther to understanding the glorious entity we call the Internet.

Learning Resources

Many, very smart people have written entire books about the OSI model or entire books about specific layers. I encourage readers to check out any O’Reilly-published books about the subject or about network engineering in general.

Here are some resources I used when writing this article:

The Illustrated Network, 2nd Edition
Protocol Data Unit (PDU): https://www.geeksforgeeks.org/difference-between-segments-packets-and-frames/
Troubleshooting Along the OSI Model: https://www.pearsonitcertification.com/articles/article.aspx?p=1730891
The OSI Model Demystified: https://www.youtube.com/watch?v=HEEnLZV2wGI
OSI Model for Dummies: https://www.dummies.com/programming/networking/layers-in-the-osi-model-of-a-computer-network/

Chloe Tucker is an artist and computer science enthusiast based in Portland, Oregon. As a former educator, she's continuously searching for the intersection of learning and teaching, or technology and art. Reach out to her on Twitter @_chloetucker and check out her website at chloe.dev .

IMAGES

Presentation Layer
Presentation Layer Diagram
PPT
A Guide to the Presentation Layer
the presentation layer function
Presentation Layer

COMMENTS

Presentation Layer in OSI model
Functions of Presentation Layer : Data from Application Layer <=> Presentation layer <=> Data from Session Layer. The presentation layer, being the 6th layer in the OSI model, performs several types of functions, which are described below-Presentation layer format and encrypts data to be sent across the network.
Presentation Layer
The presentation layer is the lowest layer at which application programmers consider data structure and presentation, instead of simply sending data in the form of datagrams or packets between hosts. This layer deals with issues of string representation - whether they use the Pascal method (an integer length field followed by the specified ...
Presentation Layer: Protocols, Examples, Services
What is Presentation Layer? Definition: Presentation layer is 6th layer in the OSI model, and its main objective is to present all messages to upper layer as a standardized format.It is also known as the "Translation layer". This layer takes care of syntax and semantics of messages exchanged in between two communication systems. Presentation layer has responsible that receiver can ...
Presentation Layer: What It Is, Design Issues, Functionalities
Functionalities of the Presentation Layer. Specific functionalities of the presentation layer are as follows: 1. Translation. The processes or running programs in two machines are usually exchanging the information in the form of numbers, character strings and so on before being transmitted. The information should be changed to bitstreams ...
Presentation layer
The presentation layer ensures the information that the application layer of one system sends out is readable by the application layer of another system. On the sending system it is responsible for conversion to standard, transmittable formats. [ 7] On the receiving system it is responsible for the translation, formatting, and delivery of ...
Presentation Layer in OSI Model
The presentation layer is the 6 th layer from the bottom in the OSI model. This layer presents the incoming data from the application layer of the sender machine to the receiver machine. It converts one format of data to another format of data if both sender and receiver understand different formats; hence this layer is also called the ...
What is presentation layer?
The presentation layer is located at Layer 6 of the OSI model. The tool that manages Hypertext Transfer Protocol ( HTTP) is an example of a program that loosely adheres to the presentation layer of OSI. Although it's technically considered an application-layer protocol per the TCP/IP model, HTTP includes presentation layer services within it.
Presentation Layer of the OSI Model: Definition and Function
Functions of the presentation layer The presentation layer is the residing layer of a computer's operating system. It communicates with the application layer, from which it receives data inputted by the user. This layer performs three important functions in the transmission of data between computers. These are:
Presentation Layer in OSI Model
The Presentation Layer is a crucial component of the OSI model, responsible for ensuring that data exchanged between systems is in a format that can be understood and used. By performing functions such as data translation, formatting, compression, and encryption, the Presentation Layer plays a vital role in maintaining data integrity ...
Presentation layer and Session layer of the OSI model
The presentation layer is the sixth layer of the OSI Reference model. It defines how data and information is transmitted and presented to the user. It translates data and format code in such a way that it is correctly used by the application layer. It identifies the syntaxes that different applications use and formats data using those syntaxes.
Presentation Layer of the OSI Model
The presentation layer in the OSI model has five main functions within the frame of presentation layer protocols. Character Code Translation A character code is a representation of text using a ...
Presentation Layer
Functions of Presentation Layer. Translation: Before being transmitted, the information in the form of characters and numbers should be changed to bitstreams. The presentation layer is responsible for interoperability between encoding methods as different computers use different encoding methods. It translates data between the formats the ...
Presentation Layer of OSI Reference Model
The presentation layer manages these abstract data structures and allows higher-level data structures(eg: banking records), to be defined and exchanged. Functions of Presentation Layer. Translation: Before being transmitted, information in the form of characters and numbers should be changed to bit streams. The presentation layer is responsible ...
A Guide to the Presentation Layer
Functions of the presentation layer. As the sixth layer in the OSI model, the presentation layer is thus responsible for three general functions: translation, compression, and encryption and decryption. Translation. Layer 6 translates data based on the host's needs.
What is the presentation layer?
The presentation layer interacts closely with the application layer, which is located directly above it. The presentation layer's main task is to present data in such a way that it can be understood and interpreted from both the system sending the data and the system receiving it. After this has been accomplished, the application layer then determines how the data should be structured and ...
What is Presentation Layer in the OSI Model?
Key functions of the Presentation Layer in the OSI model include: Data Encryption: It securely encrypts data to prevent unauthorized access during transmission. Data Compression: It reduces data ...
What is the OSI model? How to explain and remember its 7 layers
Layer 6: Presentation. The Presentation Layer represents the area that is independent of data representation at the application layer. In general, it represents the preparation or translation of ...
The Presentation Layer of OSI Model
The Presentation Layer of OSI Model. The presentation layer (Layer 6) ensures that the message is presented to the upper layer in a standardized format. It deals with the syntax and the semantics of the messages. The main functions of the presentation layer are as follows −. It encodes the messages from the user dependent format to the common ...
Presentation Layer of OSI Model (Layer-6)
Important functions performed by Presentation Layer are listed here: The first & most important is, of course Data Formatting & Representation. When the presentation layer receives data from the application layer, to be sent over the network, it makes sure that the data is in the proper format. If it is not, the presentation layer converts the ...
OSI model
The session layer is meant to store states between two connections, like what we use cookies for when working with web programming. The presentation layer is meant to convert between different formats. This was simpler when the only format that was worried about was character encoding, ie ASCII and EBCDIC. When you consider all of the different ...
The OSI Model
The Session Layer initiates, maintains, and terminates connections between two end-user applications. It responds to requests from the presentation layer and issues requests to the transport layer. OSI Layer 6. Layer 6 is the presentation layer. This layer is responsible for data formatting, such as character encoding and conversions, and data ...
Presentation Layer
The Presentation Layer in the OSI model is defined as the layer that enables interaction between different application layer implementations by translating data formats and languages to facilitate communication. ... The Presentation layer performs certain functions that are requested sufficiently often to warrant finding a general solution for ...
Presentation Layer ln OSI Model
🔥Post Graduate Program In Cyber Security: https://www.simplilearn.com/pgp-cyber-security-certification-training-course?utm_campaign=PresentationLayerInOSIMo...

Layer 6 Presentation Layer

OSI Layer 6 - Presentation Layer

CASE common application service element

SASE specific application service element

Layer 7 Application Layer

Presentation Layer: Protocols, Examples, Services | Functions of Presentation Layer

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