why presentation layer is important

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Prerequisite : OSI Model

Introduction : Presentation Layer is the 6th layer in the Open System Interconnection (OSI) model. This layer is also known as Translation layer, as this layer serves as a data translator for the network. The data which this layer receives from the Application Layer is extracted and manipulated here as per the required format to transmit over the network. The main responsibility of this layer is to provide or define the data format and encryption. The presentation layer is also called as Syntax layer since it is responsible for maintaining the proper syntax of the data which it either receives or transmits to other layer(s).

Functions of Presentation 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.
This layer takes care that the data is sent in such a way that the receiver will understand the information (data) and will be able to use the data efficiently and effectively.
This layer manages the abstract data structures and allows high-level data structures (example- banking records), which are to be defined or exchanged.
This layer carries out the encryption at the transmitter and decryption at the receiver.
This layer carries out data compression to reduce the bandwidth of the data to be transmitted (the primary goal of data compression is to reduce the number of bits which is to be transmitted).
This layer is responsible for interoperability (ability of computers to exchange and make use of information) between encoding methods as different computers use different encoding methods.
This layer basically deals with the presentation part of the data.
Presentation layer, carries out the data compression (number of bits reduction while transmission), which in return improves the data throughput.
This layer also deals with the issues of string representation.
The presentation layer is also responsible for integrating all the formats into a standardized format for efficient and effective communication.
This layer encodes the message from the user-dependent format to the common format and vice-versa for communication between dissimilar systems.
This layer deals with the syntax and semantics of the messages.
This layer also ensures that the messages which are to be presented to the upper as well as the lower layer should be standardized as well as in an accurate format too.
Presentation layer is also responsible for translation, formatting, and delivery of information for processing or display.
This layer also performs serialization (process of translating a data structure or an object into a format that can be stored or transmitted easily).

Features of Presentation Layer in the OSI model: Presentation layer, being the 6th layer in the OSI model, plays a vital role while communication is taking place between two devices in a network.

List of features which are provided by the presentation layer are:

Presentation layer could apply certain sophisticated compression techniques, so fewer bytes of data are required to represent the information when it is sent over the network.
If two or more devices are communicating over an encrypted connection, then this presentation layer is responsible for adding encryption on the sender’s end as well as the decoding the encryption on the receiver’s end so that it can represent the application layer with unencrypted, readable data.
This layer formats and encrypts data to be sent over a network, providing freedom from compatibility problems.
This presentation layer also negotiates the Transfer Syntax.
This presentation layer is also responsible for compressing data it receives from the application layer before delivering it to the session layer (which is the 5th layer in the OSI model) and thus improves the speed as well as the efficiency of communication by minimizing the amount of the data to be transferred.

Working of Presentation Layer in the OSI model : Presentation layer in the OSI model, as a translator, converts the data sent by the application layer of the transmitting node into an acceptable and compatible data format based on the applicable network protocol and architecture. Upon arrival at the receiving computer, the presentation layer translates data into an acceptable format usable by the application layer. Basically, in other words, this layer takes care of any issues occurring when transmitted data must be viewed in a format different from the original format. Being the functional part of the OSI mode, the presentation layer performs a multitude (large number of) data conversion algorithms and character translation functions. Mainly, this layer is responsible for managing two network characteristics: protocol (set of rules) and architecture.

Presentation Layer Protocols : Presentation layer being the 6th layer, but the most important layer in the OSI model performs several types of functionalities, which makes sure that data which is being transferred or received should be accurate or clear to all the devices which are there in a closed network. Presentation Layer, for performing translations or other specified functions, needs to use certain protocols which are defined below –

Apple Filing Protocol (AFP): Apple Filing Protocol is the proprietary network protocol (communications protocol) that offers services to macOS or the classic macOS. This is basically the network file control protocol specifically designed for Mac-based platforms.
Lightweight Presentation Protocol (LPP): Lightweight Presentation Protocol is that protocol which is used to provide ISO presentation services on the top of TCP/IP based protocol stacks.
NetWare Core Protocol (NCP): NetWare Core Protocol is the network protocol which is used to access file, print, directory, clock synchronization, messaging, remote command execution and other network service functions.
Network Data Representation (NDR): Network Data Representation is basically the implementation of the presentation layer in the OSI model, which provides or defines various primitive data types, constructed data types and also several types of data representations.
External Data Representation (XDR): External Data Representation (XDR) is the standard for the description and encoding of data. It is useful for transferring data between computer architectures and has been used to communicate data between very diverse machines. Converting from local representation to XDR is called encoding, whereas converting XDR into local representation is called decoding.
Secure Socket Layer (SSL): The Secure Socket Layer protocol provides security to the data that is being transferred between the web browser and the server. SSL encrypts the link between a web server and a browser, which ensures that all data passed between them remains private and free from attacks.

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The OSI Model: What It Is and Why It’s Important

01-26-22 Flash Gooden

What are the seven layers of the OSI model? Let’s demystify the application, presentation, session, transport, network, data link, and physical layers to better understand how we digitally communicate with one another.

I spent a great portion of my career in telecommunications. While I was there, I worked on an assortment of jobs that helped me to connect thousands of people to the internet from the physical side: installing modems, running fiber optics to commercial and residential areas, and even placing utility poles into the ground and attaching connections on them to light up the city with the internet. My career also allowed me to work on cloud farms setting up servers, databases, and network racks.

Before I got into web development as a career at Sparkbox, I always wondered how all of the hardware components I worked with properly transferred all that data through so many conduits. I wrote this article to demystify some of the architecture that allows us to communicate with one another using devices, like our phones, computers, smart home devices...or anything that uses the internet.

Transferring data over Wi-Fi or cabling is no easy task…but it’s not magic either. The ability to communicate with one another in a matter of seconds is a luxury that we may sometimes take for granted. During my journey to understand network communication better, I stumbled across different resources about how computer systems communicate, mainly the TCP/IP Model and the Open Systems Interconnection (OSI) Model. Learning about these models helped me to become more knowledgeable in how computer systems transform code to light and vice versa. The model that first caught my interest was the OSI Model, which is the format that I will focus on here.

What Is the OSI Model?

Let me preface this breakdown by saying that the OSI model is not the standard in how our networks communicate today, but it did serve as a framework to get to the more widely adopted TCP/IP model . The OSI model is simply an idea about how our computer network systems can communicate. It has become one of the pioneering concepts for how we communicate through multiple layers of network transmission by using necessary components, from physical computer parts to fully built applications. This network communication process involves seven layers:

By using layers, we can separate the responsibilities of the network communication process, which makes things easier to troubleshoot. Learning each layer’s responsibility helps us understand how our data is managed and transformed.

The Application Layer: What It Is and Why It’s Important

The application layer is where applications can initially make network requests to send down the pipeline. This is usually where users can send messages, request web pages, or download music by interacting with our devices. These interactions become messages that typically travel through the code that we write, destined to become signals that will shoot light beams to any distance.

This layer is important because it focuses on how our network requests choose initial communication protocols. These protocols will give specific information about how we want our network request to be sent. One of the most popular protocols is HTTP, which is used by Google Chrome, Safari, and Firefox to send and receive information displayed on web pages. Communication from this protocol is sent to or received from the presentation layer.

The Presentation Layer: What It Is and Why It’s Important

Because our network requests come from other applications, they need to communicate with your Operating System. Whether you use OSX, Windows, or Linux, this layer helps translate what the browser or other applications data consists of to make it more universally digestible for other computer processes.

This layer is important because it helps translate the application code into code geared to send over a network. When we want to send data, we can’t send it as a regular “string,” a.k.a. text. Even if you are sending a network transmission that consists of just a few letters, such as your name, it must be converted to 1s and 0s (binary) for it to be readable by the other parts of the network transmission process. The presentation layer is also important because it involves encrypting information before it is sent over a network or decrypting a network transmission if we are receiving data.

The Session Layer: What It Is and Why It’s Important

The session layer is responsible for creating, regulating, and destroying connections between systems. Once the operating system knows that it needs to send data, this layer manages how long that connection should remain open and ensures that we receive all of the information we are requesting or sending before terminating itself.

When we send data, it does not reach our devices all at once. Think of the session layer as a traffic light that signals us when we have more information. When that process is completed, it prevents unnecessary data from reaching our system. This layer also handles a bit of authentication so that we can trust that the data reaching us is coming from the place that we requested.

The Transport Layer: What It Is and Why It’s Important

The transport layer controls the limits set on the information that we transport around our application process. This layer determines the size or block of information to transport and how fast that data can be transmitted to or from us.

We can compare the transport layer to a highway. On this road, we are getting information about a truck that has our valuable cargo on it. The truck can go at a certain speed, and we’ve informed the packing company of exactly how many items we need on the back of that truck. In other words, the transport layer is essentially making sure that the cargo (data) is supplied in a way that we anticipate. Most network services usually utilize two transporting protocols: TCP (Transmission Control Protocol) or UDP (User Datagram Protocol). We may use TCP if we want reliable, stellar data that we can’t afford to lose (e.g., FTP & email), or UDP when we need fast data and may be okay with the occasional packet drop (e.g., live streaming, online gaming, etc.).

The Network Layer: What It Is and Why It’s Important

The network layer, also known as “level three,” is responsible for managing the movement of data from one host computer to the next. It allows packet management to find the shortest route to where the data needs to go. This is controlled by packet management devices such as a router.

Routers have long saved us by identifying which computer is sending a message. Being able to give computers logical addresses so that data can be requested or received is beneficial because we don’t want data floating around the internet– it should have a specific destination. Routers examine a frame, which essentially is data that contains a source and destination address. This frame also includes a “Payload”—a.k.a. the piece of data sent down the pipeline. This layer uses IP addresses to ensure that network requests go to the intended computer.

The Data Link Layer: What It Is and Why It’s Important

The data link layer, also known as DLL or “layer two”, is a complex layer that divides itself into two additional layers called the Logical Link Control (LLC), and the Media Access Control (MAC). This layer ensures that the delivery from computer node to computer node is complete. It is usually controlled by the Network Interface Card (NIC).

This part of the network request dictates how two machines talk to one another. The “frames” that the network layer examines are assembled by the data link layer. The MAC portion helps us to avoid collisions of our data if we send multiple requests while also establishing the medium in which our data will be sent (wireless vs. wired). The main job of the LLC is to identify our network protocols and analyze our frames for errors.

The Physical Layer: What It Is and Why It’s Important

The last layer of the network application process is handled on the physical layer. This is where modems, cables, or hubs handle data. It captures the whole frame data and converts the data transmissions to bits.

Light travels through fiber optic cables at 124,188 miles per second—that’s fast! We use satellites, fiber optic cables, routers, modems, and many other physical interfaces to send data from one world location to another. The physical layer is all about doing the heavy lifting by transporting our light waves at “warp” speed.

These layers allow us to conceptualize what a complete network transmission, from top to bottom, would look like. Our data will traverse each layer, and convert the code that we write into data that different protocols can interpret. If we want better insight into how modern networks have used this as a realistic platform, we can also look at the TCP/IP model to see what layers are used in today’s network transmissions.

Additional Reading:

The OSI Model Doesn’t Map Well to TCP/IP

The Actual OSI Model

Internet Protocol Suite

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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

Sase specific application service element, 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

Last Edited

What is the Presentation Layer?

Presentation Layer is the Layer 6 of the seven-layer Open Systems Interconnection (OSI) reference model . The presentation layer structures data that is passed down from the application layer into a format suitable for network transmission. This layer is responsible for data encryption, data compression, character set conversion, interpretation of graphics commands, and so on. The network redirector also functions at this layer.

Presentation Layer functions

Translation: Before being transmitted, information in the form of characters and numbers should be changed to bit streams. Layer 6 is responsible for interoperability between encoding methods as different computers use different encoding methods. It translates data between the formats the network requires and the format the computer.
Encryption: Encryption at the transmitter and decryption at the receiver
Compression: Data compression to reduce the bandwidth of the data to be transmitted. The primary role of data compression is to reduce the number of bits to be transmitted. Multimedia files, such as audio and video, are bigger than text files and compression is more important.

Role of Presentation Layer in the OSI Model

This layer is not always used in network communications because its functions are not always necessary. Translation is only needed if different types of machines need to talk with each other. Encryption is optional in communication. If the information is public there is no need to encrypt and decrypt info. Compression is also optional. If files are small there is no need for compression.

Explaining Layer 6 in video

Most real-world protocol suites, such as TCP/IP , do not use separate presentation layer protocols. This layer is mostly an abstraction in real-world networking.

An example of a program that loosely adheres to layer 6 of OSI is the tool that manages the Hypertext Transfer Protocol (HTTP) — although it’s technically considered an application-layer protocol per the TCP/IP model.

However, 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.

It 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 be used to present the file to the user.

In short, the presentation layer

Makes sure that data which is being transferred or received should be accurate or clear to all the devices which are there, in a closed network.

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

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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.

Understanding the Role of the Presentation Layer in Data Format Translation and Security

1. introduction.

According to a recent study conducted by the Institute of Electrical and Electronics Engineers (IEEE), the presentation layer is responsible for ensuring that the data is in a format that is acceptable to the application layer. This includes data compression and decompression, encryption and decryption, and character set conversion. In today’s data-driven world, the ability to effectively manage and secure data is becoming increasingly important, and understanding the role of the presentation layer in this process is crucial.

This article will explore the techniques and technologies used in the presentation layer to perform data format translation, compression and decompression, and encryption and decryption. This will include a discussion of the benefits and limitations of these techniques, as well as real-life examples and case studies of their implementation. By the end of this article, readers will have a solid understanding of the role and functions of the presentation layer in the OSI model and how it contributes to secure and efficient data transmission.

2. The role of the presentation layer

The presentation layer, also known as the syntax layer, is the sixth layer in the OSI model. It ensures that the data is in a format acceptable to the application layer. This includes data format translation, compression and decompression, encryption and decryption, and character set conversion. It acts as an interface between the application layer and the rest of the layers in the OSI model.

Data Format Translation:

The presentation layer is responsible for translating data between different formats so the application layer can understand it. For example, it may convert a file from one format, such as TIFF, to another format, such as JPEG. This ensures that the data is in a form that is compatible with the application layer and can be processed accordingly.

Compression and Decompression:

Another essential function of the presentation layer is data compression and decompression. The layer compresses the data before sending it to the next layer, the network layer. This reduces the amount of data that needs to be transmitted, reducing the time required for the data to be shared. Once the data reaches the destination, the decompression process takes place, and the data is restored to its original form. There are various compression and decompression techniques like LZ77, LZ78, and Huffman coding that are used to compress and decompress data.

3. Data compression and decompression techniques

Data compression and decompression are essential functions of the presentation layer in the OSI model. Compression refers to reducing the amount of data that needs to be transmitted. At the same time, decompression restores the data to its original form once it reaches the destination. The use of compression techniques can significantly reduce the amount of time required for data to be transmitted, as well as reduce the bandwidth needed for transmission.

The presentation layer’s most commonly used compression techniques include LZ77, LZ78, and Huffman coding.

LZ77 is a lossless data compression algorithm that Abraham Lempel and Jacob Ziv first introduced in 1977. It replaces repeated instances of a data string concerning the original series. LZ77 is a dictionary-based algorithm that uses a sliding window to identify and replace repeated data instances. This technique is effective at compressing data that contains many repeated patterns, but it can be less effective on highly random data.

LZ78 is another lossless data compression algorithm that Lempel and Ziv introduced in 1978. It is similar to LZ77 but uses a different data compression approach. Instead of using a sliding window, LZ78 uses a dictionary of previously encountered data strings. This approach allows LZ78 to achieve higher compression ratios than LZ77 but also requires more memory and processing power.

Huffman coding:

Huffman coding is a lossless data compression algorithm introduced by David Huffman in 1952. Huffman coding is a variable-length coding algorithm that assigns shorter codes to more frequently occurring symbols in the data. This technique is especially effective for compressing data that contains many repeating characters, such as text or DNA sequences.

Each technique has its advantages and disadvantages; LZ77 and LZ78 are simpler than Huffman coding and can be implemented quickly. With a limited amount of memory, on the other hand, Huffman coding is more efficient in terms of compression ratio, but it is more complex and memory-intensive.

In real-life examples, all three algorithms have been used in various applications. For instance, LZ77 has been used to compress data in the telecommunications industry, and LZ78 has been used in data storage devices like hard drives and flash drives. In contrast, Huffman coding compresses text, images, audio and video files.

4. Encryption and decryption in the presentation layer

Encryption and decryption are essential security measures that are used to protect sensitive information as it is transmitted over a network. In the OSI model, encryption and decryption occur at the presentation layer. The presentation layer is responsible for ensuring that the data is in a format acceptable to the application layer, and it also ensures that the information is protected during transmission.

Encryption refers to converting plain text into an unreadable form, known as ciphertext. The ciphertext can only be read and understood by someone with the correct decryption key. Decryption, on the other hand, is the process of converting ciphertext back into plain text using the right decryption key.

The importance of encryption and decryption in the presentation layer is clear, especially with the rise of cyber threats. It ensures that only authorised parties can access and understand the sensitive information being transmitted. Without encryption and decryption, sensitive data would be vulnerable to eavesdropping and tampering.

There are two main types of encryption and decryption methods that are commonly used in the presentation layer: symmetric key encryption and asymmetric key encryption.

Symmetric key encryption:

Symmetric key encryption is a method of encryption where the same key is used for both encryption and decryption. This method is fast and efficient, but it also has some drawbacks. The main disadvantage is that the key must be securely exchanged between the sender and the receiver before any encryption can occur.

Asymmetric key encryption:

Asymmetric key encryption, also known as public key encryption, is a method of encryption where a pair of keys is used. One key is used for encryption, and the other is used for decryption. This method is more secure than symmetric key encryption because the key used for encryption can be made public, while the key used for decryption is kept private.

In real life, symmetric key encryption is used for bulk encryption, for example, in the transportation of email, instant messaging and other types of data where the speed of encryption is more important than key exchange. On the other hand, Asymmetric key encryption is often used for digital signatures, online transactions and handshaking in secure connections.

5. Common Attacks on the Presentation Layer

The Presentation Layer in the OSI model ensures data security during transmission. However, like any other layer in the OSI model, it is also vulnerable to various attacks, vulnerabilities, and threats. These can have severe consequences, such as unauthorised access or manipulation of sensitive information.

One standard attack on the presentation layer is a “format string attack”. This occurs when an attacker can insert random formatting characters into a string, which can then be used to disrupt the normal execution of a program. This can lead to various consequences, including buffer overflows, which can be used to execute arbitrary code or crash the system.

Another attack that targets the presentation layer is “malicious code injection”. This occurs when an attacker can insert malicious code into a seemingly benign file or message. This can be done by exploiting vulnerabilities in data format translation or compression/decompression mechanisms. Once the malicious code is executed, it can cause various types of damage, such as data loss, unauthorised access to sensitive information, or even complete system compromise.

In addition to these specific attacks, the presentation layer is vulnerable to more general threats, such as “man-in-the-middle” or “replay” attacks. These are attacks in which an attacker intercepts and alters communications between two parties to gain unauthorised access to sensitive information. Such attacks can occur on any OSI model layer, but they are particularly dangerous when they target the presentation layer, as the attacker can manipulate or intercept data in transit.

6. How to Secure the Presentation Layer

Securing the Presentation Layer in the OSI model is crucial for protecting sensitive information during transmission. There are various security best practices that organisations can implement to protect against attacks, vulnerabilities, and threats on this layer.

One critical best practice is to keep software and systems up-to-date with the latest security patches and updates. This ensures that known vulnerabilities are fixed, making it harder for attackers to exploit them. It’s also important to regularly monitor systems and networks for signs of suspicious activity, such as unusual traffic patterns or login attempts.

Another best practice is to use secure protocols for data transmission and storage. Examples of secure protocols used at the Presentation Layer are Transport Layer Security (TLS) and Secure Sockets Layer (SSL), which encrypt communications between parties. Additionally, the use of robust encryption and decryption mechanisms, such as symmetric and asymmetric key encryption, can help protect against man-in-the-middle and replay attacks.

Enforcing strict access controls and implementing a solid data classification system can also secure the presentation layer. This includes access controls to limit who can view, modify or delete sensitive data and a data classification system which can help determine how data is handled, processed and protected.

Implementing a robust incident response plan that includes detailed procedures for identifying, containing and reporting security incidents can also be a valuable asset in case of a security breach. It’s also important to regularly train employees on security best practices and to make them aware of the importance of security in the presentation layer.

In addition, performing regular penetration testing, Vulnerability Assessments, and security audits can also help to identify and address security vulnerabilities. This can include testing the effectiveness of encryption and decryption mechanisms, evaluating the robustness of access controls, and identifying potential vulnerabilities in data format translation and compression/decompression mechanisms.

7. Conclusion

In conclusion, the presentation layer in the OSI model is a critical component in the data transmission process. Its functions include data format translation, data compression and decompression, and encryption and decryption. These functions are vital to ensure that the data is in a format compatible with the application layer and to protect the data during transmission.

We have discussed how the presentation layer plays a vital role in the OSI model. The techniques and technologies used in the presentation layer to perform data format translation, compression and decompression, encryption and decryption. The article also includes the advantages and disadvantages of each technique, real-life examples and case studies, if applicable, that illustrate the concepts and makes them more relatable.

The topic of the presentation layer in the OSI model is essential for anyone working in the network security and communications field, as it provides an understanding of how data is protected and formatted during transmission. We hope this article has provided a comprehensive understanding of the role and functions of the presentation layer in the OSI model.

However, it’s important to note that the Presentation Layer, like any other layer in the OSI model, is also vulnerable to various attacks, vulnerabilities, and threats. Therefore, it is crucial to implement security best practices to protect against these threats, such as keeping software and systems up-to-date with the latest security patches and updates, using secure protocols, and robust encryption and decryption mechanisms. Strict access controls, incident response plans, and regular security assessments can also help secure the Presentation Layer.

8. FAQs on the Presentation Layer

How does the presentation layer ensure data format compatibility?

The presentation layer ensures data format compatibility by providing a set of protocols and standards for data representation and encoding. These protocols, such as ASCII or Unicode, define a standard format for data so that it can be easily understood and processed by different systems. This helps to ensure that data can be exchanged between other systems without loss of meaning or integrity.

How does the presentation layer protect data during transmission?

The presentation layer protects data during transmission by using various encryption techniques to ensure that the data is secure as it is transmitted over a network. Encryption is the process of converting plaintext data into a coded format (ciphertext) unreadable by unauthorised parties. Standard encryption methods used at the presentation layer include SSL (Secure Sockets Layer) and TLS (Transport Layer Security).

What are some standard encryption algorithms used in the presentation layer?

Some standard encryption algorithms used in the presentation layer include:

RSA (Rivest-Shamir-Adleman)
AES (Advanced Encryption Standard)
DES (Data Encryption Standard)
3DES (Triple Data Encryption Standard)
What is the difference between symmetric and asymmetric encryption in the presentation layer?

Symmetric key encryption and asymmetric key encryption are both encryption methods that are used to protect data during transmission, but they use different techniques to secure the data.

Symmetric key encryption uses a single shared key for encryption and decryption, meaning that the sender and receiver both have to use the same key to encrypt and decrypt the data.

Asymmetric key encryption, also called public-key encryption, uses a pair of keys, one for encryption (the public key) and one for decryption (the private key). So the sender uses the recipient’s public key to encrypt the data, and the recipient uses their private key to decrypt the data.

How does the presentation layer handle data format translation for different data types?

The presentation layer handles data format translation for different data types using a set of protocols and standards for data representation and encoding. These protocols, such as ASCII or Unicode, define a standard format for data so that it can be easily understood and processed by different systems. The presentation layer can also use data conversion algorithms to convert data between other formats, such as a Word document to a PDF.

How does the presentation layer interact with other layers in the OSI model?

The presentation layer, the sixth layer in the OSI model, acts as an intermediary between the application layer (layer 7) and the session layer (layer 5). It is responsible for translating data between different formats and encoding schemes, and it is also responsible for compressing and decompressing data. The presentation layer communicates with the application layer to convert the data it receives into a format the application can understand. It also communicates with the session layer to establish, manage, and terminate sessions between networked devices.

How do changes in data formats affect the presentation layer?

Changes in data formats can have a significant impact on the presentation layer, as the presentation layer is responsible for converting data between different formats. The presentation layer must be updated when data formats change to support the new design. If this is done, the presentation layer can convert the data, which may be unreadable or lost. Additionally, there are changes in the protocol or standard used in the presentation layer. In that case, it will affect the compatibility with other systems, so the sending and receiving ends have to use the same protocol. Otherwise, they would not be able to understand each other.

How does the presentation layer handle data compression and decompression in real-time communications?

The presentation layer is responsible for compressing and decompressing data in real-time communications. Compression reduces data size to improve transmission efficiency, while decompression restores the data to its original format. The presentation layer uses various compression algorithms to compress data and the same algorithms to decompress the data when it is received.

In real-time communications, the presentation layer might use lossless compression algorithms to compress the data in order not to lose any information but at the same time still be able to compress the data to a smaller size.

How can data integrity be maintained in the presentation layer?

Data integrity in the presentation layer can be maintained using encryption, secure hash algorithms, and error-detection codes.

Encryption is the process of converting plaintext data into a coded format (ciphertext) that is unreadable by unauthorised parties. This helps to protect data from unauthorised access and modification during transmission.

Secure hash algorithms are used to create a unique digital signature for each piece of data, which can be used to verify the integrity of the data upon receipt. This helps to detect any changes or modifications that may have occurred during transmission.

Error-detection codes are used to detect errors in the data during transmission and can help to correct these errors.

Additionally, the presentation layer can also use a digital signature or digital certificate to ensure the authenticity of data, which is the process of using a digital signature to ensure that the data is not tampered with during transmission.

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 .

7 layers of the OSI model

Breaking up networking functions into layered functionalities helps network engineers understand the workings of their networks better and helps them zero in on the problems more quickly. Here’s how each layer serves that purpose.

Layer 1: Physical layer

Layer 1 is the physical layer and also the lowest layer of the OSI model. This layer transmits information in the form of bits (1s and 0s) from one node to the next. Components of the physical layer include cables, power plugs, connectors, network interface cards (NICs), and other hardware.

Layer 2: Data link layer (DLL)

The data link layer (DLL) is the second layer and handles the node-to-node transfer of data. Its primary function is to ensure that the transferred data is error-free.

DLL comprises two sub-layers: logical link control (LLC) and media access control (MAC). LLC handles multiplexing and demultiplexing signals as well as node flow control and error management, while MAC handles hardware interactions with the network.

Layer 3: Network layer

The network layer is responsible for routing data packets from a source host to a destination host. It does so by selecting the shortest possible path. This layer is also responsible for packet forwarding and logical addressing. Necessary protocols used in this layer are ICMP , ARP, RIP, IPv4/v6, and IPsec.

Layer 4: Transport layer

The transport layer is responsible for transferring data from hosts to users. The most frequently used protocols in the transport layer are User Datagram Protocol (UDP) and Transmission Control Protocol (TCP). While TCP enables data transfer between computing devices, UDP is designed for speedy data transmission.

Layer 5: Session layer

The session layer is responsible for controlling, managing, and terminating the connections between computers. Functions include token management, creating dialog units, synchronizing data flow, and efficiently using available network resources.

Layer 6: Presentation layer

The presentation layer handles information related to data coding and encoding. It’s also called the syntax layer.

Layer 7: Application layer

The application layer is the one that is most familiar to end users, as it governs communication with software housed on their host PCs. Note that this layer doesn’t include the actual software or application itself, but only the protocols that manage them.

How the OSI model works

The OSI model works by segmenting all transmitted data through a seven-layer abstraction in order to more efficiently and securely parse and deliver the data to its destination.

To better understand this process, here’s an example of the OSI model’s abstraction process in operation. Let’s say you decide to send an email from computer (A) to computer (B).

Your email application client resides on layer 7. When you send the email, the layer 7 application protocol encapsulates or places a header on your messages and sends it to layer 6.

Layer 6 compresses the data and transfers it to layer 5. It also encrypts the data before sending it forward.

Layer 5 opens a session between your computer and the outgoing server. It also decides which data packet belongs to which file. Finally, it adds an appropriate header and transfers the data to layer 4.

When layer 4 receives data from layer 5, it segments it and assigns each segment a destination and source port number to ensure the data gets delivered to the correct service. Layer 4 also enforces security controls.

Layer 3 breaks the data into packets and transmits it over multiple paths. The packets contain destination and source IP addresses for easier identification of end devices.

Then the data is sent to layer 2, where the DLL adds MAC addresses to the packets, which are then grouped into frames. To deliver to the correct destination, the LLC sublayer adds control information to each frame.

Finally, the frames are transmitted to layer 1 in the form of 1s and 0s. That binary data is then transferred to device B either through electric pulses (Ethernet), radio waves (Wi-Fi), or light pulses (Fiber optics).

Layer 1 ensures bit synchronization so that, as the data reverses its abstraction through each layer at the destination, the end user receives the information in a readable format—just as it was intended.

Why the OSI model is still relevant

Although the TCP/IP model is the preferred model for IT professionals and is used in most modern computers, the OSI model remains relevant for its easy troubleshooting, flexible nature, and continued use as a teaching tool.

Easy troubleshooting

The OSI model enables IT teams to classify their asset inventories into easily digestible chunks at each layer. In case of a problem, spotting and identifying problems within the layers is relatively easy thanks to their specificity—especially at the top three layers, which are all collapsed into one in the TCP/IP model.

Flexibility

The OSI model supports both connectionless services as well as connection-oriented services, making it highly flexible in nature.

Acts as a teaching aid

The OSI model serves as an excellent teaching aid as it provides users with a clear understanding of how software and hardware work together. By breaking down networking concepts into layers, it removes ambiguity and provides network professionals with a clear picture of networking.

Drawbacks of the OSI model

Although the OSI model does have benefits, it does fall short in some areas, including practicality, popularity, and complexity.

Theoretical model

Compared to TCP/IP, OSI functions as more of a theoretical framework that doesn’t offer many solutions for practical implementation.

Less popular

While the OSI model was developed at the same time as the TCP/IP model, it couldn’t compete with the popularity of TCP/IP. IT professionals generally preferred TCP/IP protocols more; as a result, the OSI model fell increasingly out of favor.

More complex

The OSI model is quite complicated and thus has implementation problems. In contrast, the TCP/IP model is more effective and easier to operate.

Duplication

There’s a lot of duplication of services in the OSI model. For instance, both the transport and the data layer provide similar services. To add to it, several layers, like the presentation or the session layer, are barely used, which is in part why they were collapsed into the application layer in TCP/IP.

OSI vs. TCP/IP model

The Transmission Control Protocol/Internet Protocol (TCP/IP) is a communication protocol that shows how a particular computer can connect to another over the internet. The model has a four-layer architecture and is designed to ensure the transmission of error-free data in the form of packets across networks.

From top to bottom, the four layers of the TCP/IP model comprise the application layer, transport layer, internet layer, and network access layer.

While both OSI and the TCP/IP model have a layered architecture and provide almost the same functionalities, they have several dissimilarities. They include:

OSI is a conceptual framework, while TCP/IP is a connection-oriented protocol
TCP/IP has 4 layers, while OSI has 7 layers
OSI uses the session layer, presentation layer, and application layer to demarcate the upper layers, while TCP/IP uses only the application layer
Layers 1 and 2 are separate in the OSI model, but in TCP/IP they are combined
The layers in the OSI model are highly interdependent. So, if the lower layer fails, there is a probability that the upper layers will also not work well either. In contrast, TCP/IP offers a more flexible architecture.

OSI and TCP/IP layers compared

The below table shows how the TCP/IP model simplifies the layering system compared to OSI’s more granular and complex model.

What does the future of the OSI model look like?

Given the strong preference of network administrators for the TCP/IP model and its massive usage, it may be tempting to assume OSI’s days are numbered.

However, although the OSI model may no longer be popular, there’s no denying that it serves as a reference model for thousands of IT experts, aiding them in designing more efficient and reliable systems.

In fact, even today, the OSI model is referenced in product manuals and certification exams. So even if it’s unlikely that the OSI model will experience a resurgence in practical usage, it’s equally unlikely to disappear from common theoretical application altogether.

Bottom line: How the OSI model is used today

Despite not being used much in practice today, network engineers and vendors still reference the OSI model to have a complete overview of computer networking and to learn about its functions. While the TCP/IP protocol is implemented more by modern networks, still the OSI model is used as a guide by networking professionals to get clarity on data abstraction paths and processes.

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Presentation Layer Of OSI Model For Beginners

Presentation Layer:

Presentation Layer is the sixth layer in the OSI model and here are some of the functionalities of the presentation layer:

Translation

Before being transmitted, the data remains in the form of characters and numbers. This data has to be changed to bitstreams before transmission. The presentation layer is responsible for interoperability between encoding methods as different computers use different encoding methods. It translates data between the formats that a network requires and the format a computer needs.

It carries out the process of encryption at the transmitter end and the process of decryption at the receiver end.

Encryption and decryption are ways to protect the confidentiality of the data stored on computer systems or wired over the internet or other computer networks.

Also Read: Network Layer Of OSI Mode: Functionalities and Protocols

In terms of security, modern-day encryption methods play a vital role in the security assurance of IT systems and communications as they can provide not only confidentiality but also, authentication and integrity.

Data compression

Data compression is also known by different names like source coding or bit-rate reduction. As evident from these names, data compression involves encoding information using fewer bits than the original representation. So in this way, the data compression can be either lossy or lossless.

Even though lossless compression reduces bits by identifying and eliminating statistical redundancy, no data information is lost in the lossless compression.

On the other hand, the lossy compression reduces bits by identifying unnecessary information and removing it.

Data compression is useful in computer networks because it helps in the following ways:

Reducing resource usages such as data storage space or transmission capacity. B
Reducing the need for an expensive hardware for the data representation. For example, if a video is highly compressed before transmission, an expensive hardware might be required to decompress the video data before playing it.

Thus, data compression is also very helpful in real-time applications over the internet like real-time video or audio streaming.

Data conversion

There are different types of operating systems such as Windows, Linux, Mac OS etc. are being used all around the world. Data conversion is, thus, responsible for the conversion of computer data from one format to another.

Different computers encode data in different ways on the basis of certain standards. On top of that, each computer program handles data in a different manner. Data conversion comes in handy in those situations when the representation of data is needed on different platforms.

The presentation layer can be composed of two sublayers: common application service element (CASE) and specific application service element (SASE).

Also Read: LLC Layer (Logical Link Control): Data Link Layer Of OSI Model

The common application service element sublayer provides services for the application layer and request services from the session layer. It provides support for common application services whereas the specific application service element sublayer provides application specific services (protocols) like remote database access, file transfer, virtual terminal.

If you have any comments or thoughts related to it, feel free to ask and correct us. Also, don’t miss our complete coverage on the Computer networks .

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What is OSI Model?

What is the OSI Model?

The Open Systems Interconnection (OSI) model is a conceptual framework that divides network communications functions into seven layers. Sending data over a network is complex because various hardware and software technologies must work cohesively across geographical and political boundaries. The OSI data model provides a universal language for computer networking, so diverse technologies can communicate using standard protocols or rules of communication. Every technology in a specific layer must provide certain capabilities and perform specific functions to be useful in networking. Technologies in the higher layers benefit from abstraction as they can use lower-level technologies without having to worry about underlying implementation details.

Why is the OSI model important?

The layers of the Open Systems Interconnection (OSI) model encapsulate every type of network communication across both software and hardware components. The model was designed to allow two standalone systems to communicate via standardised interfaces or protocols based on the current layer of operation.

The benefits of the OSI model are given next.

Shared understanding of complex systems

Engineers can use the OSI model to organize and model complex networked system architectures. They can separate the operating layer of each system component according to its main functionality. The ability to decompose a system into smaller, manageable parts via abstraction makes it easier for people to conceptualize it as a whole.

Faster research and development

With the OSI reference model, engineers can understand their work better. They know which technological layer (or layers) they’re developing for when they create new, networked systems that need to communicate with each other. Engineers can develop networked systems and take advantage of a series of repeatable processes and protocols.

Flexible standardization

The OSI model does not specify the protocols to use between levels, but rather the tasks that protocols perform. It standardizes network communication development so people can rapidly understand, build, and decompose highly complex systems—all without prior knowledge of the system. It also abstracts details, so engineers don’t require the understanding of every aspect of the model. In modern applications, the lower levels of networking and protocols are abstracted away to simplify system design and development. The following image shows how the OSI model is used in modern application development.

What are the seven layers of the OSI model?

The Open Systems Interconnection (OSI) model was developed by the International Organization for Standardization and others in the late 1970s. It was published in its first form in 1984 as ISO 7498, with the current version being ISO/IEC 7498-1:1994. The seven layers of the model are given next.

Physical layer

The physical layer refers to the physical communication medium and the technologies to transmit data across that medium. At its core, data communication is the transfer of digital and electronic signals through various physical channels like fiber-optic cables, copper cabling, and air. The physical layer includes standards for technologies and metrics closely related with the channels, such as Bluetooth, NFC, and data transmission speeds.

Data link layer

The data link layer refers to the technologies used to connect two machines across a network where the physical layer already exists. It manages data frames, which are digital signals encapsulated into data packets. Flow control and error control of data are often key focuses of the data link layer. Ethernet is an example of a standard at this level. The data link layer is often split into two sub-layers: the Media Access Control (MAC) layer and Logical Link Control (LLC) layer.

Network layer

The network layer is concerned with concepts such as routing, forwarding, and addressing across a dispersed network or multiple connected networks of nodes or machines. The network layer may also manage flow control. Across the internet, the Internet Protocol v4 (IPv4) and IPv6 are used as the main network layer protocols.

Transport layer

The primary focus of the transport layer is to ensure that data packets arrive in the right order, without losses or errors, or can be seamlessly recovered if required. Flow control, along with error control, is often a focus at the transport layer. At this layer, commonly used protocols include the Transmission Control Protocol (TCP), a near-lossless connection-based protocol, and the User Datagram Protocol (UDP), a lossy connectionless protocol. TCP is commonly used where all data must be intact (e.g. file share), whereas UDP is used when retaining all packets is less critical (e.g. video streaming).

Session layer

The session layer is responsible for network coordination between two separate applications in a session. A session manages the beginning and ending of a one-to-one application connection and synchronization conflicts. Network File System (NFS) and Server Message Block (SMB) are commonly used protocols at the session layer.

Presentation layer

The presentation layer is primarily concerned with the syntax of the data itself for applications to send and consume. For example, Hypertext Markup Language (HTML) , JavaScipt Object Notation (JSON) , and Comma Separated Values (CSV) are all modeling languages to describe the structure of data at the presentation layer.

Application layer

The application layer is concerned with the specific type of application itself and its standardized communication methods. For example, browsers can communicate using HyperText Transfer Protocol Secure (HTTPS), and HTTP and email clients can communicate using POP3 (Post Office Protocol version 3) and SMTP (Simple Mail Transfer Protocol).

Not all systems that use the OSI model implement every layer.

How does communication happen in the OSI model?

The layers in the Open Systems Interconnection (OSI) model are designed so that an application can communicate over a network with another application on a different device, no matter the complexity of the application and underlying systems. To do this, various standards and protocols are used to communicate with the layer above or below. Each of the layers is independent and only aware of the interfaces to communicate with the layer above and below it.

By chaining together all these layers and protocols, complex data communications can be sent from one high-level application to another. The process works as follows:

The sender’s application layer passes data communication down to the next lower layer.
Each layer adds its own headers and addressing to the data before passing it on.
Data communication moves down the layers until it is eventually transmitted through the physical medium.
At the other end of the medium, each layer processes the data according to the relevant headers at that level.
At the receiver end, data moves up the layer and is gradually unpacked until the application at the other end receives it.

What are alternatives to the OSI model?

Various networking models were used in the past, such as Sequenced Packet Exchange/Internet Packet Exchange (SPX/IPX) and Network Basic Input Output System (NetBIOS). Today, the main alternative to the Open Systems Interconnection (OSI) model is the TCP/IP model.

The TCP/IP model

The TCP/IP model is comprised of five different layers:

The physical layer
The data link layer
The network layer
The transport layer
They application layer

While layers like the physical layer, network layer, and application layer appear to map directly to the OSI model, this isn’t quite the case. Instead, the TCP/IP model most accurately maps to the structure and protocols of the internet.

The OSI model remains a popular networking model to describe how networking operates from a holistic perspective for educational purposes. However, the TCP/IP model is now more commonly used in practice.

A note on proprietary protocols and models

It’s important to note that not all internet-based systems and applications follow the TCP/IP model or the OSI model. Similarly, not all offline-based networked systems and applications use the OSI model or any other model.

Both the OSI and TCP/IP models are open standards. They’re designed so that anyone can use them, or further build them out to meet specific requirements.

Organizations also design their own internal, proprietary standards, including protocols and models, that are closed-source and only for use within their systems. Sometimes, they may subsequently release them to the public for interoperability and further community development. An example is s2n-tls, a TLS protocol that was originally a proprietary Amazon Web Services (AWS) protocol but is now open source.

How can AWS meet your computer networking requirements?

AWS helps organizations design, deploy, and scale networked systems and applications with less friction.

We have a robust suite of AWS Networking and Content Delivery offerings. They’re designed to complement and integrate with your internal applications and services, across all levels of network operations. Here are some examples:

AWS App Mesh provides secure, application-level networking for all your services, with built-in communications monitoring and control
Amazon CloudFront is a content delivery network (CDN) service built for high performance, security, and developer convenience
AWS Direct Connect offers a direct connection, which doesn’t touch the internet, from your organization to your AWS resources
Elastic Load Balancing (ELB) distributes incoming network traffic across AWS targets to improve application scalability

Get started with networked systems and applications on AWS by creating an account today.

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API Testing: What It Is, Why It’s Important & How to Do It

Published: August 09, 2023

The global API testing market is projected to reach 1.8 billion USD by 2026, up from 641.6 Million in 2020, according to a report by Global Industry Analysts Inc .

This market growth corresponds to the rise in cloud applications and interconnected platforms that require application programming interfaces (APIs) . More APIs mean more testing to determine that they meet expectations for functionality, reliability, performance, and security. Without this testing, an API may fail to perform as expected, which can impact many softwares and services.

In this post, you will learn:

types of API testing
why API testing is important
how to perform API testing

What is API testing?

API testing is the process of sending requests to an API and monitoring the responses to ensure its behaving as expected. API testing is designed to assess the functionality, reliability, performance, and security of an API, and is therefore an essential part of the API development lifecycle.

Software application development is dominated by the three-layered architecture approach, which is an architecture made up of a presentation layer, business logic layer, and database layer.

three layer architecture in software application includes presentation, business, and data access layer

Why is API testing important?

API testing is important for ensuring that your API performs as expected when faced with a wide variety of expected and unexpected requests. This process is designed to not only test the API’s functionality — but also its reliability, performance, and security.

API testing is also important because it offers several advantages over other types of testing, like unit and UI testing.

For example, unit tests are designed to verify the functionality of individual components within a single application whereas API tests are designed to verify that all system components function as intended. This broader test coverage makes it easier to identify any bugs in the unit, database, and server levels.

API tests are also faster to run and more isolated than UI tests, which makes it quicker and easier to identify and resolve bugs. According to data from Andersen Lab , a UI test runs for approximately seven minutes while an API test runs for 12 seconds. Meaning, an API test is about 35 times faster than a UI test.

Perhaps most importantly, API testing allows developer operations, quality assurance, development, and other teams to begin testing an application’s core functionality before the user interface is ready. This enables them to identify any errors or weaknesses early on in the development process. If identified later in the process, these errors and weaknesses in the build can be costly to fix, requiring large amounts of code to be rewritten and significantly delaying the product’s release.

Now that we understand some of the benefits of API testing, let’s walk through how to perform it.

How to Do API Testing

Review the API specification.
Determine API testing requirements.
Define input parameters.
Create positive and negative tests.
Select an API testing tool.

1. Review the API specification.

Before you start testing, you need to first understand the purpose of the API, how the API functions, and what results to expect when using the API. To do so, you can review the API specification.

For example, if you’re testing an HTTP API, then you can review the OpenAPI specification , which defines a standard, programming language-agnostic interface description for HTTP APIs. This specification details all the HTTP API’s objects, values, and parameters, how the objects are called, what each object does, and how they can be used together. The section below details how the Request Body Object is supposed to function, what its fixed fields are, what to expect when using this function, and request body examples.

Request Body Objection section in the OpenAPI specification

API Automation and the Future

With an increasing number of services relying on hundreds of interconnected APIs, API testing is expected to continue to grow in importance. API automation , through robust API testing, is the key to maintaining connectivity in the digital economy and enabling faster product releases. It allows for accurate, repeatable, and efficient testing processes, crucial to keeping up with the speed and scope of today's software development.

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Presentation Layer in OSI model
Prerequisite : OSI Model. Introduction : Presentation Layer is the 6th layer in the Open System Interconnection (OSI) model. This layer is also known as Translation layer, as this layer serves as a data translator for the network. The data which this layer receives from the Application Layer is extracted and manipulated here as per the required ...
The OSI Model: What It Is and Why It's Important
The OSI model includes the application, presentation, session, transport, network, data link, and physical layers. By using layers, we can separate the responsibilities of the network communication process, which makes things easier to troubleshoot. Learning each layer's responsibility helps us understand how our data is managed and transformed.
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 ...
What is the presentation layer?
The presentation layer is the sixth layer of the OSI model. It is primarily used to convert different file formats between the sender and the receiver.The OSI model is a reference model that is used to define communication standards between two devices within a network.The development of this standard began in the 1970s and it was first published at the beginning of the following decade.
Presentation Layer
Presentation Layer is the Layer 6 of the seven-layer Open Systems Interconnection (OSI) reference model. The presentation layer structures data that is passed down from the application layer into a format suitable for network transmission. This layer is responsible for data encryption, data compression, character set conversion, interpretation ...
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 ...
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 ...
Understanding the Role of the Presentation Layer in Data Format
The presentation layer, also known as the syntax layer, is the sixth layer in the OSI model. It ensures that the data is in a format acceptable to the application layer. This includes data format translation, compression and decompression, encryption and decryption, and character set conversion. It acts as an interface between the application ...
Presentation Layer of the OSI Model
The presentation layer is a very important layer because it handles encryption, decryption, and the conversion of complex data into flat-byte strings, a format that is easily transmittable. 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.
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 ...
What Is the OSI Model? Why It's Still Relevant
The presentation layer handles information related to data coding and encoding. It's also called the syntax layer. Layer 7: Application layer. The application layer is the one that is most familiar to end users, as it governs communication with software housed on their host PCs. Note that this layer doesn't include the actual software or ...
Presentation Layer Of OSI Layer For Beginners
The presentation layer is an important layer in the OSI model because it is responsible for some of the important services like data conversion, data compression, encryption, and decryption.
The OSI Model and You Part 6: Stopping Threats at the OSI Presentation
After the OSI presentation layer, we'll look at the application layer. By far, this is where the widest range of attacks and breaches can occur. Therefore, it's very important to understand.
What is the OSI Model?
The Open Systems Interconnection (OSI) model is a conceptual framework that divides network communications functions into seven layers. Sending data over a network is complex because various hardware and software technologies must work cohesively across geographical and political boundaries. The OSI data model provides a universal language for ...
What is the Presentation Layer, Anyway?
It's the presentation layer that knows to put the right information into the appropriate fields of a customer record, for example: Name, Date of Birth, Address, etc. The presentation layer is where you'll find the code for making a program look nice as well. Most importantly to this discussion, the presentation layer is where RPA functions.
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: Translation
PDF Presentation Layer
The presentation layer is concerned with preserving the meaning of information sent across a network. The presentation layer may represent (encode) the data in various ways (e.g., data compression, or encryption), but the receiving peer will convert the encoding back into its original meaning. The presentation layer concerns itself with 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 ...
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 ...
Lec 10: Transport layer, Session Layer, and Presentation Layer
The Transport Layer makes ensuring that data is sent across host systems and that end-to-end communication is consistent and effective. In a networked context, it performs several crucial tasks ...
Presentation layer definition
Presentation layer definition. The presentation layer is the sixth layer in the Open System Interconnection (OSI) model. It serves as the data translator for the network — it takes data formats from different sources and presents it to the application layer in an accurate, well-defined, and standardized manner. Real presentation layer functions
API Testing: What It Is, Why It's Important & How to Do It
It must take information inputted by the user from the presentation layer, query the database layer and transform that data according to the business logic, and present the results back to the user via the presentation layer. But the business logic layer must also communicate with other applications as well as human users. To do so, it uses an API.

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The OSI Model: What It Is and Why It’s Important

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The Presentation Layer: What It Is and Why It’s Important

The Session Layer: What It Is and Why It’s Important

The Transport Layer: What It Is and Why It’s Important

The Network Layer: What It Is and Why It’s Important

The Data Link Layer: What It Is and Why It’s Important

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2. The role of the presentation layer

3. Data compression and decompression techniques

4. Encryption and decryption in the presentation layer

5. Common Attacks on the Presentation Layer

6. How to Secure the Presentation Layer

7. Conclusion

8. FAQs on the Presentation Layer

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

Prerequisites

Learning Objectives

Common Networking Terms

What is the OSI Model?

OSI Layer 1

How to Troubleshoot OSI Layer 1 Problems

OSI Layer 2

How to Troubleshoot OSI Layer 2 Problems

OSI Layer 3

How to Troubleshoot OSI Layer 3 Problems

OSI Layer 4

How to Troubleshoot OSI Layer 4 Problems

OSI Layer 5

How to Troubleshoot OSI Layer 5 Problems

OSI Layer 6

How to Troubleshoot OSI Layer 6 Problems

OSI Layer 7

How to Troubleshoot OSI Layer 7 Problems

Learning Resources

7 layers of the OSI model

Layer 1: Physical layer

Layer 2: Data link layer (DLL)

Layer 3: Network layer

Layer 4: Transport layer