brief description about presentation layer

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Presentation Layer in OSI model

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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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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 and Session layer of the OSI model

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

The Presentation Layer

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

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

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

Examples of the presentation layer

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

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

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

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

Functions of the presentation layer

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

Session layer

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

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

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

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

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

Functions of the session layer

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

Examples of the session layer

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

By ComputerNetworkingNotes Updated on 2023-10-30 05:30:01 IST

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

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brief description about presentation layer

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Presentation layer in osi model.

Last Updated on March 7, 2024 by Abhishek Sharma

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

What is Presentation Layer in OSI Model?

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

Functions of the Presentation Layer

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

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

Importance of the Presentation Layer

Importance of Presentation Layer are:

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

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

FAQs related to Presentation Layer in OSI Model

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

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

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

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

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

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

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 .

What is the presentation layer in the OSI model?

The presentation layer is the sixth layer in the OSI model and is responsible for converting different file formats. This allows two systems to communicate. Other tasks carried out by the sixth layer include data compression and encryption.

What is the presentation layer?

What does the presentation layer do, which format does the presentation layer use, presentation layer protocols, skipping 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. This standard enables seamless interaction between different technical systems.

The model is made up of a total of seven different layers, all having their own clearly defined tasks. While there are clear boundaries between the layers, the layers interact with each other, with each layer building off the one below it. The different layers are as follows:

Physical layer
Data link layer
Network layer
Transport layer
Session layer
Presentation layer
Application layer

The presentation layer interacts closely with the application layer, which is located directly above it. The presentation layer’s main task is to present data in such a way that it can be understood and interpreted from both the system sending the data and the system receiving it. After this has been accomplished, the application layer then determines how the data should be structured and what sort of data and values are permissible.

Using these entries, a command set, or an abstract transfer syntax, is then automatically created. The presentation layer now has the task of transferring the data in such a way that it is readable without changing the information contained within it.

The presentation layer is often also responsible for the encryption and decryption of data . The information is first encrypted on the sender’s side and then sent to the receiver in an encrypted state. Keys and encryption methods are then exchanged in the presentation layer. The recipient is then able to decrypt the unreadable data and convert it into a format that can be understood and interpreted.

If data is shown during a transfer, we often use the term transfer syntax. These are separated into the abstract transfer syntax , in which the transferred values are written, and the concrete syntax, which contains a definition of the value coding.

The receiver can only process and understand the data they receive if they receive all of the information from the presentation layer. The most common definition language is Abstract Syntax Notation One (ASN.1) , which is also recommended by the ISO. The ISO is an organization that is responsible for developing international standards in technology, management and manufacturing.

The presentation layer has many different formats. The most common text formats are the ASCII (American Standard Code for Information Interchange) and EBCDIC (Extended Binary-Coded Decimal Interchange Code). The most common image formats are GIF, JPEG and TIFF. Widely used video formats include MIDI, MPEG and QuickTime.

There are many different presentation layer protocols as well as transfer and encryption technologies in the presentation layer. These include:

The tasks which are carried out by the presentation layer are not always necessary for communication between two systems. In instances where both systems use the same formats, data conversion is not necessary. Additionally, encryption and compression are not required for every interaction and can also be carried out in another layer of the OSI model. If this is the case, the presentation layer can be skipped and the application layer (7) can communicate directly with the session layer (5) instead .

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Home » Computer Network

Presentation Layer: What It Is, Design Issues, Functionalities

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

What is Presentation Layer?

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

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

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

Design Issues with Presentation Layer

The following are the design issues with presentation layer:

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

Functionalities of the Presentation Layer

Specific functionalities of the presentation layer are as follows:

1. Translation

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

Example: Convert ASCII code to EBCDIC code.

2. Encryption

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

3. Compression

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

How-To Geek

The 7 osi networking layers explained.

The Open Systems Interconnection (OSI) networking model defines a conceptual framework for communications between computer systems.

Quick Links

Physical Layer
Data Link Layer
Network Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer

The Open Systems Interconnection (OSI) networking model defines a conceptual framework for communications between computer systems. The model is an ISO standard which identifies seven fundamental networking layers, from the physical hardware up to high-level software applications.

Each layer in the model handles a specific networking function. The standard helps administrators to visualize networks, isolate problems, and understand the use cases for new technologies. Many network equipment vendors advertise the OSI layer that their products are designed to slot into.

OSI was adopted as an international standard in 1984. It remains relevant today despite the changes to network implementation that have occurred since first publication. Cloud, edge, and IoT can all be accommodated within the model.

In this article, we'll explain each of the seven OSI layers in turn. We'll start from the lowest level, labelled as Layer 1.

1. Physical Layer

All networking begins with physical equipment. This layer encapsulates the hardware involved in the communications, such as switches and cables. Data is transferred as a stream of binary digits - 0 or 1 - that the hardware prepares from input it's been fed. The physical layer specifies the electrical signals that are used to encode the data over the wire, such as a 5-volt pulse to indicate a binary "1."

Errors in the physical layer tend to result in data not being transferred at all. There could be a break in the connection due to a missing plug or incorrect power supply. Problems can also arise when two components disagree on the physical encoding of data values. In the case of wireless connections, a weak signal can lead to bit loss during transmission.

2. Data Link Layer

The model's second layer concerns communication between two devices that are directly connected to each other in the same network. It's responsible for establishing a link that allows data to be exchanged using an agreed protocol. Many network switches operate at Layer 2.

The data link layer will eventually pass bits to the physical layer. As it sits above the hardware, the data link layer can perform basic error detection and correction in response to physical transfer issues. There are two sub-layers that define these responsibilities: Logical Link Control (LLC) that handles frame synchronization and error detection, and Media Access Control (MAC) which uses MAC addresses to constrain how devices acquire permission to transfer data.

3. Network Layer

The network layer is the first level to support data transfer between two separately maintained networks. It's redundant in situations where all your devices exist on the same network.

Data that comes to the network layer from higher levels is first broken up into packets suitable for transmission. Packets received from the remote network in response are reassembled into usable data.

The network layer is where several important protocols are first encountered. These include IP (for determining the path to a destination), ICMP, routing, and virtual LAN. Together these mechanisms facilitate inter-network communications with a familiar degree of usability. However operations at this level aren't necessarily reliable: messages aren't required to succeed and may not necessarily be retried.

4. Transport Layer

The transport layer provides higher-level abstractions for coordinating data transfers between devices. Transport controllers determine where data will be sent and the rate it should be transferred at.

Layer 4 is where TCP and UDP are implemented, providing the port numbers that allow devices to expose multiple communication channels. Load balancing is often situated at Layer 4 as a result, allowing traffic to be routed between ports on a target device.

Transport mechanisms are expected to guarantee successful communication. Stringent error controls are applied to recover from packet loss and retry failed transfers. Flow control is enforced so the sender doesn't overwhelm the remote device by sending data more quickly than the available bandwidth permits.

5. Session Layer

Layer 5 creates ongoing communication sessions between two devices. Sessions are used to negotiate new connections, agree on their duration, and gracefully close down the connection once the data exchange is complete. This layer ensures that sessions remain open long enough to transfer all the data that's being sent.

Checkpoint control is another responsibility that's held by Layer 5. Sessions can define checkpoints to facilitate progress updates and resumable transmissions. A new checkpoint could be set every few megabytes for a file upload, allowing the sender to continue from a particular point if the transfer gets interrupted.

Many significant protocols operate at Layer 5 including authentication and logon technologies such as LDAP and NetBIOS. These establish semi-permanent communication channels for managing an end user session on a specific device.

6. Presentation Layer

The presentation layer handles preparation of data for the application layer that comes next in the model. After data has made it up from the hardware, through the data link, and across the transport, it's almost ready to be consumed by high-level components. The presentation layer completes the process by performing any formatting tasks that may be required.

Decryption, decoding, and decompression are three common operations found at this level. The presentation layer processes received data into formats that can be eventually utilized by a client application. Similarly, outward-bound data is reformatted into compressed and encrypted structures that are suitable for network transmission.

TLS is one major technology that's part of the presentation layer. Certificate verification and data decryption is handled before requests reach the network client, allowing information to be consumed with confidence that it's authentic.

7. Application Layer

The application layer is the top of the stack. It represents the functionality that's perceived by network end users. Applications in the OSI model provide a convenient end-to-end interface to facilitate complete data transfers, without making you think about hardware, data links, sessions, and compression.

Despite its name, this layer doesn't relate to client-side software such as your web browser or email client. An application in OSI terms is a protocol that caters for the complete communication of complex data through layers 1-6.

HTTP, FTP, DHCP, DNS, and SSH all exist at the application layer. These are high-level mechanisms which permit direct transfers of user data between an origin device and a remote server. You only need minimal knowledge of the workings of the other layers.

The seven OSI layers describe the transfer of data through computer networks. Understanding the functions and responsibilities of each layer can help you identify the source of problems and assess the intended use case for new components.

OSI is an abstract model that doesn't directly map to the specific networking implementations commonly used today. As an example, the TCP/IP protocol works on its own simpler system of four layers: Network Access, Internet, Transport, and Application. These abstract and absorb the equivalent OSI layers: the application layer spans OSI L5 to L7, while L1 and L2 are combined in TCP/IP's concept of Network Access.

OSI remains applicable despite its lack of direct real-world application. It's been around so long that it's widely understood among administrators from all backgrounds. Its relatively high level of abstraction has also ensured it's remained relevant in the face of new networking paradigms, many of which have targeted Layer 3 and above. An awareness of the seven layers and their responsibilities can still help you appreciate the flow of data through a network while uncovering integration opportunities for new components.

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What is the OSI Model?

The OSI Model Defined

The OSI Model (Open Systems Interconnection Model) is a conceptual framework used to describe the functions of a networking system. The OSI model characterizes computing functions into a universal set of rules and requirements in order to support interoperability between different products and software. In the OSI reference model, the communications between a computing system are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

Created at a time when network computing was in its infancy, the OSI was published in 1984 by the International Organization for Standardization (ISO). Though it does not always map directly to specific systems, the OSI Model is still used today as a means to describe Network Architecture.

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The 7 Layers of the OSI Model
Physical Layer

The lowest layer of the OSI Model is concerned with electrically or optically transmitting raw unstructured data bits across the network from the physical layer of the sending device to the physical layer of the receiving device. It can include specifications such as voltages, pin layout, cabling, and radio frequencies. At the physical layer, one might find “physical” resources such as network hubs, cabling, repeaters, network adapters or modems.

Data Link Layer

At the data link layer, directly connected nodes are used to perform node-to-node data transfer where data is packaged into frames. The data link layer also corrects errors that may have occurred at the physical layer.

The data link layer encompasses two sub-layers of its own. The first, media access control (MAC), provides flow control and multiplexing for device transmissions over a network. The second, the logical link control (LLC), provides flow and error control over the physical medium as well as identifies line protocols.

Network Layer

The network layer is responsible for receiving frames from the data link layer, and delivering them to their intended destinations among based on the addresses contained inside the frame. The network layer finds the destination by using logical addresses, such as IP (internet protocol). At this layer, routers are a crucial component used to quite literally route information where it needs to go between networks.

Transport Layer

The transport layer manages the delivery and error checking of data packets. It regulates the size, sequencing, and ultimately the transfer of data between systems and hosts. One of the most common examples of the transport layer is TCP or the Transmission Control Protocol.

Session Layer

The session layer controls the conversations between different computers. A session or connection between machines is set up, managed, and termined at layer 5. Session layer services also include authentication and reconnections.

Presentation Layer

The presentation layer formats or translates data for the application layer based on the syntax or semantics that the application accepts. Because of this, it at times also called the syntax layer. This layer can also handle the encryption and decryption required by the application layer.

Application Layer

At this layer, both the end user and the application layer interact directly with the software application. This layer sees network services provided to end-user applications such as a web browser or Office 365. The application layer identifies communication partners, resource availability, and synchronizes communication.

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Physical Layer

Digital Transmission
Multiplexing
Circuit-Switched
Message-Switched Networks
Packet Switching

Transport layer

Transport Layer
Telnet vs SSH
UDP Protocol
TCP - Protocol

ISO/OSI REFERENCE MODEL

Introduction to Reference Models
OSI Model: Physical Layer
OSI Model: Datalink Layer
OSI Model: Network Layer
OSI Model: Transport Layer
OSI Model: Session Layer
OSI Model: Presentation Layer
OSI Model: Application Layer

TCP/IP REFERENCE MODELCOMPUTER NETWORKS

The TCP/IP Reference Model
Difference between OSI and TCP/IP Model
Key Terms - Computer Network

Session layer

Session Layer

Computer Networks

Components of Computer Networks
Features of Computer Network
Protocols and Standards
Connection Oriented and Connectionless
OSI Vs TCP/IP

Presentation layer

Presentation Layer

Application layer

HTTP Protocol
FTP Protocol
SMTP Protocol
POP Protocol
SNMP Protocol
Electronic Mail
MIME Protocol
World Wide Web
DNS Protocol

Presentation Layer - OSI Model

The primary goal of this layer is to take care of the syntax and semantics of the information exchanged between two communicating systems. Presentation 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. Languages(syntax) can be different of the two communicating systems. Under this condition presentation layer plays a role translator.

In order to make it possible for computers with different data representations to communicate, the data structures to be exchanged can be defined in an abstract way. The presentation layer manages these abstract data structures and allows higher-level data structures(eg: banking records), to be defined and exchanged.

Functions of Presentation Layer

Translation: Before being transmitted, information in the form of characters and numbers should be changed to bit streams. The presentation layer is responsible 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: It carries out encryption at the transmitter and decryption at the receiver.
Compression: It carries out 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 0transmitted. It is important in transmitting multimedia such as audio, video, text etc.

Design Issues with Presentation Layer

To manage and maintain the Syntax and Semantics of the information transmitted.
Encoding data in a standard agreed upon way. Eg: String, double, date, etc.
Perform Standard Encoding on wire.
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See how imperva can help, what is the osi model.

The Open Systems Interconnection (OSI) model describes seven layers that computer systems use to communicate over a network. It was the first standard model for network communications, adopted by all major computer and telecommunication companies in the early 1980s

The modern Internet is not based on OSI, but on the simpler TCP/IP model. However, the OSI 7-layer model is still widely used, as it helps visualize and communicate how networks operate, and helps isolate and troubleshoot networking problems.

OSI was introduced in 1983 by representatives of the major computer and telecom companies, and was adopted by ISO as an international standard in 1984.

OSI Model Explained: The OSI 7 Layers

We’ll describe OSI layers “top down” from the application layer that directly serves the end user, down to the physical layer.

7. Application Layer

The application layer is used by end-user software such as web browsers and email clients. It provides protocols that allow software to send and receive information and present meaningful data to users. A few examples of application layer protocols are the Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Post Office Protocol (POP), Simple Mail Transfer Protocol (SMTP), and Domain Name System (DNS).

6. Presentation Layer

The presentation layer prepares data for the application layer. It defines how two devices should encode, encrypt, and compress data so it is received correctly on the other end. The presentation layer takes any data transmitted by the application layer and prepares it for transmission over the session layer.

5. Session Layer

The session layer creates communication channels, called sessions, between devices. It is responsible for opening sessions, ensuring they remain open and functional while data is being transferred, and closing them when communication ends. The session layer can also set checkpoints during a data transfer—if the session is interrupted, devices can resume data transfer from the last checkpoint.

4. Transport Layer

The transport layer takes data transferred in the session layer and breaks it into “segments” on the transmitting end. It is responsible for reassembling the segments on the receiving end, turning it back into data that can be used by the session layer. The transport layer carries out flow control, sending data at a rate that matches the connection speed of the receiving device, and error control, checking if data was received incorrectly and if not, requesting it again.

3. Network Layer

The network layer has two main functions. One is breaking up segments into network packets, and reassembling the packets on the receiving end. The other is routing packets by discovering the best path across a physical network. The network layer uses network addresses (typically Internet Protocol addresses) to route packets to a destination node.

2. Data Link Layer

The data link layer establishes and terminates a connection between two physically-connected nodes on a network. It breaks up packets into frames and sends them from source to destination. This layer is composed of two parts—Logical Link Control (LLC), which identifies network protocols, performs error checking and synchronizes frames, and Media Access Control (MAC) which uses MAC addresses to connect devices and define permissions to transmit and receive data.

1. Physical Layer

The physical layer is responsible for the physical cable or wireless connection between network nodes. It defines the connector, the electrical cable or wireless technology connecting the devices, and is responsible for transmission of the raw data, which is simply a series of 0s and 1s, while taking care of bit rate control.

Advantages of OSI Model

The OSI model helps users and operators of computer networks:

Determine the required hardware and software to build their network.
Understand and communicate the process followed by components communicating across a network.
Perform troubleshooting, by identifying which network layer is causing an issue and focusing efforts on that layer.

The OSI model helps network device manufacturers and networking software vendors:

Create devices and software that can communicate with products from any other vendor, allowing open interoperability
Define which parts of the network their products should work with.
Communicate to users at which network layers their product operates – for example, only at the application layer, or across the stack.

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OSI vs. TCP/IP Model

The Transfer Control Protocol/Internet Protocol (TCP/IP) is older than the OSI model and was created by the US Department of Defense (DoD). A key difference between the models is that TCP/IP is simpler, collapsing several OSI layers into one:

OSI layers 5, 6, 7 are combined into one Application Layer in TCP/IP
OSI layers 1, 2 are combined into one Network Access Layer in TCP/IP – however TCP/IP does not take responsibility for sequencing and acknowledgement functions, leaving these to the underlying transport layer.

Other important differences:

TCP/IP is a functional model designed to solve specific communication problems, and which is based on specific, standard protocols. OSI is a generic, protocol-independent model intended to describe all forms of network communication.
In TCP/IP, most applications use all the layers, while in OSI simple applications do not use all seven layers. Only layers 1, 2 and 3 are mandatory to enable any data communication.

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OSI Presentation and Application Layers

Cite this chapter.

Paul D. Bartoli 3

Part of the book series: Applications of Communications Theory ((ACTH))

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This chapter discusses the Application and Presentation Layers of the Reference Model of Open Systems Interconnection (OSI) [1]. The Application and Presentation Layers perform functions necessary to exchange information between application processes; the Application Layer is concerned with the semantic aspects of the information exchange, while the Presentation Layer is concerned with the syntactic aspects. The ability to manage the semantic and syntactic elements of the information to be exchanged is key to ensuring that the information can be interpreted by the communicants.

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ISO 7498, “Information processing systems—Open Systems Interconnection—Basic Reference Model,” 1984. CCITT Recommendation X.200, “Reference model of open systems interconnection for CCITT applications,” 1984 (updated expected in 1988).

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ISO DIS 9545, “Information processing systems—Open Systems Interconnection—Application Layer structure,” September 1988.

ISO TR 9007, “Concepts and terminology for the conceptual schema and the information base,” 1985.

ISO 8649, “Information processing systems—Open systems interconnection—Service definition for the association control service element,” 1988. ISO 8650, “Information processing systems—Open systems interconnection—Protocol specification for the association control service element,” 1988. CCITT Recommendation X.217, “Association control service definition for open systems interconnection for CCITT applications,” 1988. CCITT Recommendation X.227, “Association control protocol specification for open systems interconnection for CCITT applications,” final text December, 1987.

ISO 8571, “Information processing systems—Open systems interconnection—File transfer, access, and management,” Parts 1–4, 1988.

ISO/DIS 9804, “Information processing systems”Open systems interconnection—Service definition for commitment, concurrency, and recovery,” 1988 (text in SC 21 N 2573, March, 1988). ISO DIS 9805, “Information processing systems—Open systems interconnection—Protocol specification for commitment, concurrency, and recovery,” 1988 (text in SC 21 N 2574, March, 1988). CCITT Recommendation X.237, “Commitment, concurrency, and recovery service definition,” Draft Text, 1988. CCITT Recommendation X.247, “Commitment, concurrency, and recovery protocol specification, Draft Text, 1988.

ISO DIS 9040, “Information processing systems—Open systems interconnection—Virtual terminal service—Basic class,” 1988 (text in SC 21 N 2615, March, 1988). ISO DIS 9041, “Information processing systems—Open systems interconnection—Virtual terminal protocol—Basic class,” 1988 (text in SC 21 N 2616, March, 1988).

ISO DIS 9066–1, “Reliable transfer service”, 1988 (text in SC 18 N 1408, March, 1988). ISO DIS 9066–2, “Reliable transfer protocol specification,” 1988 (text in SC 18 N 1409). CCITT Recommendation X.218, “Reliable transfer: Model and service definition,” 1988. CCITT Recommendation X.228, “Reliable transfer: Protocol specification,” 1988.

ISO DIS 9072–1, “Remote operations service,” 1988 (text in SC 18 N 1410, March, 1988). ISO DIS 9072–2, “Remote operations protocol specification,” 1988 (text in SC 18 N 1411, March, 1988). CCITT Recommendation X.219, “Remote operations: Model, notation, and service definition,” 1988. CCITT Recommendation X.229, “Remote operations: Protocol specification,” 1988.

ISO DIS 9594, “Information processing—Open systems interconnection—The directory,” parts 1–8, 1988 (text in SC 21 N 2751 through N 2758, April, 1988). CCITT X.500, “Series recommendations on directory,” November, 1987.

ISO DIS 10021, “Information processing—Text communication—Message oriented text interchange system,” 1988 (text in SC 18 N 1487 through N 1493, May, 1988). CCITT X.400, “Series recommendations for message handling systems,” 1988.

ISO 8613/1–8, “Office document architecture and interchange format,” 1988, awaiting publication. CCITT T.400, “Series recommendations for document architecture, transfer, and manipulation,” 1988.

ISO 8824, “Information processing systems—Open systems interconnection—Specification of abstract syntax notation one (ASN.1),” 1987; and ISO 8824/PDAD 1, “Information processing systems—Open systems interconnection—Specification for ASN.1: Proposed draft Addendum 1 on ASN.1 extensions,” 1988 (final text in SC 21 N 2341 Revised, April, 1988). CCITT Recommendation X.208, “Specification of abstract syntax notation one (ASN.1),” 1988.

ISO 8822, “Information processing systems—Open systems interconnection—Connection oriented presentation service definition,” 1988. CCITT Recommendation X.216, “Presentation service definition for open systems interconnection for CCITT applications,” 1988.

ISO 8825, “Information processing—Open systems interconnection—Specification of basic encoding rules for abstract syntax notation one (ASN.1),” 1987; and ISO 8825/ PDAD 1, “Information processing systems—Open systems interconnection—Specification of basic encoding rules for ASN.1: Proposed draft addendum 1 on ASN.1 extensions,” 1988 (text in SC 21 N 2342 Revised, April, 1988). CCITT Recommendation X.209, “Specification of basic encoding rules for abstract syntax notation one (ASN.1),” 1988.

ISO 8823, “Information processing systems—Open systems interconnection—Connection oriented presentation protocol specification,” 1988. CCITT Recommendation X.226, “Presentation protocol specification for open systems interconnection for CCITT applications,” 1988.

ISO 8326, “Information processing systems—Open systems interconnection—Basic connection oriented session service definition,” 1987; and ISO 8326/AD 2, “Information processing systems—Open systems interconnection—Basic connection oriented session service definition—Addendum 2: Incorporation of unlimited user data,” 1988. ISO 8327, “Information processing systems—Open systems interconnection—Basic connection oriented session protocol specification,” 1987; and ISO 8327/AD 2, “Information processing systems—Open systems interconnection—Basic connection oriented session protocol specification—Addendum 2: Unlimited session user data protocol specification,” 1988.

CCITT Recommendation X.215, “Session service definition for open systems interconnection for CCITT applications,” 1988. CCITT Recommendation X.225, “Session protocol specification for open systems interconnection for CCITT applications,” 1988.

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Bartoli, P.D. (1989). OSI Presentation and Application Layers. In: Sunshine, C.A. (eds) Computer Network Architectures and Protocols. Applications of Communications Theory. Springer, Boston, MA. https://doi.org/10.1007/978-1-4613-0809-6_13

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The Presentation Layer of OSI Model

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

The main functions of the presentation layer are as follows −

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

The Physical Layer of OSI Model
The Network Layer of OSI Model
The Transport Layer of OSI Model
The Session Layer of OSI Model
The Application Layer of OSI Model
The Data Link Layer of OSI Model
Explain the functions of Presentation Layer.
What is Presentation Layer?
The OSI Reference Model
What is a presentation layer?
Advantages and Disadvantages of the OSI Model
Computer Networks – Layers of OSI Model
What is the OSI Reference Model?
OSI Model in Computer Networking
Why Does the OSI Reference Model Matter?

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

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

What is Presentation Layer?

Definition : Presentation layer is 6th layer in the OSI model , and its main objective is to present all messages to upper layer as a standardized format. It is also known as the “ Translation layer “. This layer takes care of syntax and semantics of messages exchanged in between two communication systems. Presentation layer has responsible that receiver can understand all data, and it will be to implement all data languages can be dissimilar of two communication system.

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

Presentation Layer Tutorial Headlines:

In this section, we will show you all headlines about this entire article; you can check them as your choice; below shown all:

Functions of Presentation Layer

Protocols of Presentation Layer

Example of Presentation Layer Protocols

Presentation Layer Services

Design issues with presentation layer, faqs (frequently asked questions), what is meant by presentation layer in osi model, what protocols are used in the presentation layer, can you explain some presentation layer examples, what are the main functions of the presentation layer, what are services of presentation layer in osi, let’s get started, functions of presentation layer.

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

Presentation layer helps to translate from American standard code for information interchange (ASCII) to the extended binary code decimal interchange code (EBCDIC).
It deals with user interface as well as supporting for several services such as email and file transfer.
It provides encoding mechanism for translating all messages from user dependent format with common format and vice – versa.
It’s main goal for data encryption and decryption of entire data before they are getting transmission over all common platforms.
It provides data compression mechanism for source point to decrease the all bits which are transmitted. Due to this data compression system, user are able to transmit enlarge multimedia file at fastest file transfer rate.
Due to use of Data Encryption and Decryption algorithm, presentation layer provides more network protection and confidentiality while transmission data over the entire network.
This layer offers best flexibility for data translation for making connections with various kinds of servers , computers, and mainframes over the similar network.
Presentation layer has responsible to fix all translations in between all network systems .

Presentation layer is used various protocols; below list is available –

Multipurpose Internet Mail Extensions
File Transfer Protocol
Network News Transfer Protocol
Apple Filing Protocol (AFP)
Independent Computing Architecture (ICA), the Citrix system core protocol
Lightweight Presentation Protocol (LPP)
NetWare Core Protocol (NCP)
Network Data Representation (NDR)
Telnet (a remote terminal access protocol)
Tox Protocol
eXternal Data Representation (XDR)
25 Packet Assembler/Disassembler Protocol (PAD)

Example of Presentation Layer Protocols:

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

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

File Transfer Protocol (FTP) : FTP is a internet protocol, and its main goal is to transmit all files in between one host to other hosts over the internet on TCP/IP connections.

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

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

Lightweight Presentation Protocol (LPP) : This protocol is used to offer ISO presentation services on top of TCP/IP based protocol stacks.

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

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

Telnet (Telecommunication Network) : Telnet protocol was introduced in 1969, and it offers the command line interface for making communication along with remote device or server .

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

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

25 Packet Assembler/Disassembler Protocol (PAD) : Main objective of this protocol is to obtain all data from group of terminal and allots the data into X. 25 packets.

Presentation layer provides several services like as –

Data conversion
Character code translation
Compression
Encryption and Decryption
It helps to handle and maintain Syntax and Semantics of the message transmitted.
Encoding data can be done as standard agreed like as String, double, date, and more.
Standard Encoding can be done on wire.

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

Presentation layer is used various protocols like as:

Yes! In this article, already we have been explained many examples of presentation layer; you can check them.

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

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

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

If you have any experience, tips, tricks, or query regarding this issue? You can drop a comment!

Session and Presentation layers in the OSI model

Alessandro Maggio

December 29, 2016

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Session and presentation layers in the OSI stack can be considered fancy layers , as they are known only by a small part of Network Engineers. This is probably because all their features blend either in transport-layer protocols or in application-layer protocols. However, with this article, you will discover all the beauty of these two layers, learning what they do and how they are implemented.

UDP limitations

Back in the CCNA course, we found out that the only place we can see the session and presentation layers truly implemented is when they are based on UDP transport. UDP leaves some room to these two layers (if compared to TCP) because it is extremely simple and lacking features . These features can be then implemented in upper layers individually, adding modularity. Just to refresh your mind, UDP has the following two limitations.

UDP, all by itself, do not order packets, and therefore the receiver cannot guess in which order they were sent originally. Moreover, it is not reliable, what is lost is just lost, no UDP component will trigger a re-transmission. Adding these features, however, would increase the complexity of the algorithm behind UDP running on hosts and will add extra fields in the UDP header sent with every segment. All of that, and specifically the extra bytes added in the segment’s header, is called overhead : the extra amount of information that allows application data to be delivered correctly. Our goal is to obtain the delivery of application data as we want it with the least overhead possible .

In the article about advanced TCP , we already explained the ways we can reduce the TCP overhead using selective ACK and header compression, but all of these complex items cannot reduce the TCP header to the size of a UDP header. Instead, with UDP we follow a different approach: we start from almost no features (only delivery to the correct application using port numbers) and we add the features we need in upper layers.

Session layer

The session layer is the one implementing one-to-one application sessions: it defines the re-transmission of data, the segment ordering method, and control the communication in general. All these features are covered by TCP for applications using that transport protocol, but applications that leverage UDP have to implement these features autonomously (within the application) or rely on an extra protocol specifically sitting at the session layer. Many applications (such as TFTP) rely on the first option, while the second alternative is the privileged one for VoIP. For VoIP traffic, the protocol we rely on for the session is the Real-time Transport Protocol (RTP) . As we are talking about applications using UDP as their underlying transport, spending some time on RTP is certainly well-worth since Voice and Video are the king applications among all UDP-based applications .

The RTP header in the picture is inserted just after the UDP header, and add extra features such as the reordering of segments and their timing, which are extremely important for an application that must run real-time. Here’s the explanation of its fields.

Version – Version of RTP, the up-to-date one is version 2
P (Padding) – Flag used to indicate whether padding is present or not in the segment
X (Extension) – Flag used to indicate whether extension header is present or not
CC (CSRC count) – Number of CSRC identifiers contained in the header
M (Marker) – Flag that, if set, indicates that this segment has some special relevance for the application
PT (Payload Type) – Indicates the type of RTP payload (e.g. for VoIP/Video stream)
Sequence number – Used from the receiver to reorder packets, incremented by one each segment sent
Timestamp – Time the segment was created, used to allow the receiver to play the content of the segment (assuming that it is audio or video) at the proper interval
SSCS – Synchronization Source Identifier, identifies a stream of UDP/RTP segments
CSRC – Contributing Source IDs, indicates the source of the audio stream, multiple CSRCs can be specified if there are multiple sources (e.g. in a three-party conference)
Header extension – extra header, optional and profile-specific

These fields are the minimum needed to allow the transmission and are specifically designed for real-time streams, audio, and video mainly. Looking at the header, you can still find the Sequence number as in TCP, but no acknowledgment number . This is because RTP allows the receiver to reorder segments , but not to arrange a re-transmission. This behavior is purposefully designed this way, as a VoIP call or a video stream needs to be delivered now. In case something is lost, there is no time to re-transmit it, the show must go on. If we re-transmit it, it would arrive too late so there is no point in the retransmission at all. Another interesting field adding a feature UDP is lacking is the timestamp, with that field you can know when the content was generated and reproduce the sound and video at the same interval it was generated. Otherwise, you would have audio and video streams increasing and decreasing speed according to the network connection available.

A question I’ve been asked several times when talking about reordering packets is “How they arrive in the wrong order in the first place?” and this is surely a good question. The answer has a lot to do with routing , so it lays at the Network Layer in the OSI Stack. Routers work independently from the upper layer protocols and applications, they run based on IP addressing and routes. It might happen that a node fails over the network and traffic takes a different path to avoid falling on the faulty link, or simply a router discovers a better path to a destination. Since all of this happens dynamically, at a given moment the traffic might go over a link and one second later over another. Not all links have the same speed, so it is possible that a segment sent later but over a fast link will arrive before a segment sent previously but on a slow link. Let’s have a look at the following picture.

Edge devices (computers, servers) do not know about the network infrastructure, so they just know that there is the possibility that segments are disordered during the transmission by taking different ways. Because of that, they have to implement mechanisms for reordering . Reordering is crucial to almost any application, to transfer a file we need to know the order of its part, and to transfer audio stream we need to know in which order to play the sounds.

Presentation for Real-Time applications

The presentation layer is probably the most mysterious one. This is because almost no application implements it, neither among the UDP applications. What this layer does, is to define how data should be presented to the application. Once again, coming to rescue us we have VoIP and Video stream, the ones leveraging this layer the most. Basically, when you make a VoIP call there are some parameters involved in the audio stream, such as the bitrate or the compression rate just to name a few. To have the smoothest audio stream possible, all the parties involved must agree on how they are going to exchange audio and video. RTP is the common ground that cannot be changed, here we are talking about how to write the payload of the RTP segment. In other words, we are defining the codec.

Some codecs may privilege the compression, using less bandwidth but more computational resources, others may use a lot of bandwidth but almost no computational resources or other ones require fewer resources sacrificing audio quality. No choice can be right on all occasions, the best codec for any situation depends on your needs.

Session and presentation layers in the shadow

We now know what these two layers are truly about, but let’s take a moment to check out why they are not famous like the other OSI layers. Even previously we had the chance to understand how there is almost no need to implement them, as their features are covered elsewhere, however it is time to give some examples, as in the following picture.

What the picture says is also listed below in a little more detail.

HTTP (Hyper-Text Transfer Protocol) – Used to transfer web-pages, the session layer is handled by TCP while there is no need for a presentation layer as the information is sent in simple text or raw binary
FTP (File Transfer Protocol) – Used to transfer files to and from a server, the session layer is handled by TCP while there is no need for a presentation layer as the information is sent in raw binary
SMTP (Simple Mail Transfer Protocol) – Used to send emails from a server o another, the session layer is handled by TCP while there is no need for a presentation layer as the information is sent in simple text
SSH (Secure Shell) – Used to connect to a remote device and control it via textual commands using encryption, the session layer is handled by TCP while there is no need for a presentation layer as the information is sent in simple text
IMAP (Internet Message Access Protocol) – Used to connect to an email server and check emails, the session layer is handled by TCP while there is no need for a presentation layer as the information is sent in simple text
VoIP (Voice over IP) – This is not a real protocol, but instead a type of application, RTP manages the session layer while the presentation layer exists and is managed at the application layer

This article was really lightweight, as UDP is. With this knowledge, you know all the differences between UDP and TCP and you are ready to discuss the technologies implemented in a network to support modern applications. In the following articles, we will start to see some application layer protocols before we can dive into the configuration items.

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Presentation Layer in 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 ...
What is presentation layer?
The presentation layer is located at Layer 6 of the OSI model. The tool that manages Hypertext Transfer Protocol ( HTTP) is an example of a program that loosely adheres to the presentation layer of OSI. Although it's technically considered an application-layer protocol per the TCP/IP model, HTTP includes presentation layer services within it.
Presentation Layer
The presentation layer is the lowest layer at which application programmers consider data structure and presentation, instead of simply sending data in the form of datagrams or packets between hosts. This layer deals with issues of string representation - whether they use the Pascal method (an integer length field followed by the specified ...
Presentation layer
The presentation layer ensures the information that the application layer of one system sends out is readable by the application layer of another system. On the sending system it is responsible for conversion to standard, transmittable formats. [7] On the receiving system it is responsible for the translation, formatting, and delivery of ...
Presentation layer and Session layer of the OSI model
The presentation layer is the sixth layer of the OSI Reference model. It defines how data and information is transmitted and presented to the user. It translates data and format code in such a way that it is correctly used by the application layer. It identifies the syntaxes that different applications use and formats data using those syntaxes.
A Guide to the Presentation Layer
The presentation layer is the sixth layer in the OSI model. Known as a translator, the presentation layer converts data into an accurate, well-defined, standard format after it receives it from the application layer. The converted format varies, however, based on the type of data received. Some formats include:
What is Presentation Layer in the OSI Model?
Key functions of the Presentation Layer in the OSI model include: Data Encryption: It securely encrypts data to prevent unauthorized access during transmission. Data Compression: It reduces data ...
What is the OSI model? The 7 layers of OSI explained
The seven Open Systems Interconnection layers are the following. Layer 7. The application layer. The application layer enables the user -- human or software -- to interact with the application or network whenever the user elects to read messages, transfer files or perform other network-related tasks.
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 ...
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 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 ...
Presentation Layer: What It Is, Design Issues, Functionalities
The Presentation layer is responsible for compatibility between these encoding methods. The Presentation layer at the sender's side changes the information from its sender dependent format. The Presentation layer at the receiving machine changes the common format into its receivers dependent format. Example: Convert ASCII code to EBCDIC code. 2.
The 7 OSI Networking Layers Explained
Data Link Layer. Network Layer. Transport Layer. Session Layer. Presentation Layer. Application Layer. Summary. The Open Systems Interconnection (OSI) networking model defines a conceptual framework for communications between computer systems. The model is an ISO standard which identifies seven fundamental networking layers, from the physical ...
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 ...
The OSI Model & The 7 Layers Explained
In the OSI reference model, the communications between a computing system are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Created at a time when network computing was in its infancy, the OSI was published in 1984 by the International Organization for ...
Presentation Layer of OSI Reference Model
The primary goal of this layer is to take care of the syntax and semantics of the information exchanged between two communicating systems. Presentation 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. Languages (syntax) can be different of the two ...
What is OSI Model
6. Presentation Layer. The presentation layer prepares data for the application layer. It defines how two devices should encode, encrypt, and compress data so it is received correctly on the other end. The presentation layer takes any data transmitted by the application layer and prepares it for transmission over the session layer. 5. Session Layer
Presentation Layer of the OSI Model: Definition and Function
The presentation layer is the sixth layer of the Open Systems Interconnection (OSI), model. In computer networking, the OSI model is a concept that describes the transmission of data from one computer to another. Each layer in the model is a packet of protocols, or procedures that govern data transmission, which allow the layer to execute ...
PDF 13 OSI Presentation and Application Layers
II. The Application Layer This section discusses the underlying assumptions and viewpoint that led to the development of the OSI Application Layer. The general structure of the Application Layer is presented [2]. This model describes how the Application and Presentation Layers cooperate to support the exchange of
The Presentation Layer of OSI Model
The Presentation Layer of OSI Model. The presentation layer (Layer 6) ensures that the message is presented to the upper layer in a standardized format. It deals with the syntax and the semantics of the messages. The main functions of the presentation layer are as follows −. It encodes the messages from the user dependent format to the common ...
Presentation Layer: Protocols, Examples, Services
Presentation Layer is the 6th layer in the Open System Interconnection (OSI) model where all application programmer consider data structure and presentation, beyond of simply sending the data into form of datagram otherwise packets in between the hosts. ... This protocol provides the description and encoding of entire data, and it's main goal ...
Session and Presentation layers in the OSI model
Session layer. The session layer is the one implementing one-to-one application sessions: it defines the re-transmission of data, the segment ordering method, and control the communication in general. All these features are covered by TCP for applications using that transport protocol, but applications that leverage UDP have to implement these ...
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 ...

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Layer 6 Presentation Layer

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What is the presentation layer in the OSI model?

What is the presentation layer?

Presentation Layer: What It Is, Design Issues, Functionalities

What is Presentation Layer?

Design Issues with Presentation Layer

Functionalities of the Presentation Layer

1. Translation

2. Encryption

3. Compression

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