• Engineering Mathematics
  • Discrete Mathematics
  • Operating System
  • Computer Networks
  • Digital Logic and Design
  • C Programming
  • Data Structures
  • Theory of Computation
  • Compiler Design
  • Computer Org and Architecture
  • Computer Network Tutorial

Basics of Computer Network

  • Basics of Computer Networking
  • Introduction to basic Networking Terminology
  • Goals of Networks
  • Basic characteristics of Computer Networks
  • Challenges of Computer Network
  • Physical Components of Computer Network

Network Hardware and Software

  • Types of Computer Networks
  • LAN Full Form
  • How to Set Up a LAN Network?
  • MAN Full Form in Computer Networking
  • MAN Full Form
  • WAN Full Form
  • Introduction of Internetworking
  • Difference between Internet, Intranet and Extranet
  • Protocol Hierarchies in Computer Network
  • Network Devices (Hub, Repeater, Bridge, Switch, Router, Gateways and Brouter)
  • Introduction of a Router
  • Introduction of Gateways
  • What is a network switch, and how does it work?

Network Topology

  • Types of Network Topology
  • Difference between Physical and Logical Topology
  • What is OSI Model? - Layers of OSI Model
  • Physical Layer in OSI Model
  • Data Link Layer
  • Session Layer in OSI model

Presentation Layer in OSI model

  • Application Layer in OSI Model
  • Protocol and Standard in Computer Networks
  • Examples of Data Link Layer Protocols
  • TCP/IP Model
  • TCP/IP Ports and Its Applications
  • What is Transmission Control Protocol (TCP)?
  • TCP 3-Way Handshake Process
  • Services and Segment structure in TCP
  • TCP Connection Establishment
  • TCP Connection Termination
  • Fast Recovery Technique For Loss Recovery in TCP
  • Difference Between OSI Model and TCP/IP Model

Medium Access Control

  • MAC Full Form
  • Channel Allocation Problem in Computer Network
  • Multiple Access Protocols in Computer Network
  • Carrier Sense Multiple Access (CSMA)
  • Collision Detection in CSMA/CD
  • Controlled Access Protocols in Computer Network

SLIDING WINDOW PROTOCOLS

  • Stop and Wait ARQ
  • Sliding Window Protocol | Set 3 (Selective Repeat)
  • Piggybacking in Computer Networks

IP Addressing

  • What is IPv4?
  • What is IPv6?
  • Introduction of Classful IP Addressing
  • Classless Addressing in IP Addressing
  • Classful Vs Classless Addressing
  • Classless Inter Domain Routing (CIDR)
  • Supernetting in Network Layer
  • Introduction To Subnetting
  • Difference between Subnetting and Supernetting
  • Types of Routing
  • Difference between Static and Dynamic Routing
  • Unicast Routing - Link State Routing
  • Distance Vector Routing (DVR) Protocol
  • Fixed and Flooding Routing algorithms
  • Introduction of Firewall in Computer Network

Congestion Control Algorithms

  • Congestion Control in Computer Networks
  • Congestion Control techniques in Computer Networks
  • Computer Network | Leaky bucket algorithm
  • TCP Congestion Control

Network Switching

  • Circuit Switching in Computer Network
  • Message switching techniques
  • Packet Switching and Delays in Computer Network
  • Differences Between Virtual Circuits and Datagram Networks

Application Layer:DNS

  • Domain Name System (DNS) in Application Layer
  • Details on DNS
  • Introduction to Electronic Mail
  • E-Mail Format
  • World Wide Web (WWW)
  • HTTP Full Form
  • Streaming Stored Video
  • What is a Content Distribution Network and how does it work?

CN Interview Quetions

  • Top 50 Networking Interview Questions (2024)
  • Top 50 TCP/IP interview questions and answers
  • Top 50 IP addressing interview questions and answers
  • Last Minute Notes - Computer Networks
  • Computer Network - Cheat Sheet
  • Network Layer
  • Transport Layer
  • Application Layer

Prerequisite : OSI Model

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

Functions of Presentation Layer :

The presentation layer, being the 6th layer in the OSI model, performs several types of functions, which are described below-

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

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

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

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

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

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

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

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

Chloe Tucker

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:

1-Router-Image

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?

Cave, Dragon's Lair, mountains

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:

Closeup of 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.

Koala with Photoshopped makeup

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/

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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.

What is the OSI Model?

presentation layer function in networking

OSI Model Explained

The Open Systems Interconnection (OSI) model is a framework that describes the functions of a networking system. The OSI model categorizes the computing functions of the different network components, outlining the rules and requirement needed to support the interoperability of the software and hardware that make up the network.

In addition to understanding what the OSI model is, note that the OSI model layers are particularly helpful when visualizing the flow of data from the sender to the receiver. The descriptions of the various levels, as well as their interdependency, make it easier to pinpoint networking issues. Also, programmers can use the OSI model to better understand how data gets to and from their applications or to write code specific for use at certain levels. 

In the following sections, you will see the OSI model explained.

What Are the 7 Layers of the OSI Model?

There are seven abstraction layers that make up the OSI model. Communication from one person to another goes from Layer 7 to Layer 1. Each layer performs a specific job before it sends the data on to the next layer.

Layer 7 - Application Layer

The application layer is the closest to the end-user. It initiates communication between the user and the applications they personally interact with. At this layer, data is translated from the syntax it was converted to into something the user can read.

Examples of Layer 7 applications include a web browser like Chrome, Safari, or Firefox, or an email application. Layer 7 can also identify communication partners, check to see which resources are available, and make sure communication is properly synced.

Layer 6 - Presentation Layer

The presentation layer takes care of getting data ready for the application layer. The two devices that are communicating may use different methods of encoding their data. Layer 6 therefore turns the incoming data into something that can be read at the application layer. This includes encrypting and decrypting data.

The presentation layer also compresses data that comes from the application layer before it sends it on to Layer 5, the session layer.

Layer 5 - Session Layer

The session layer handles opening and closing network communications between two interacting devices. The “session” refers to the time between the opening and closing of the interaction. The session layer makes sure the session is open for a long enough period of time for all the necessary data to be sent through. The session layer then closes the session to prevent expending unnecessary resources.

Also, it synchronizes the data transfer. If a large amount of data is being sent, the session layer can set up checkpoints. If the transmission gets interrupted before all the data is downloaded, the checkpoints allow the transmission to be resumed without it starting all over again.

Layer 4 - Transport Layer

The transport layer handles end-to-end communication between the devices interacting with each other. The management of the communication involves taking the data in the session layer and dividing it into pieces referred to as segments. The transport layer on the device receiving the communication handles the reassembly of the segments into data that is consumable by the session layer.

Also, the transport layer takes care of managing the flow and any necessary error messages that need to be sent in the event something goes wrong. To manage data flow, the transport layer makes sure it is not being sent so quickly that the receiver’s device cannot handle it. To control errors, the transport layer checks to see if the data transmitted was done so completely. If it is not, this layer will request a retransmission.

Layer 4 is where Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) port numbers work. Internet Protocol (IP) addresses operate at Layer 3, the network layer. TCP, UDP, and IP are protocols that facilitate how data is sent and received.

Layer 3 - Network Layer

The network layer facilitates the transfer of data when two networks are communicating with each other. If two communicating devices are using the same network, then there is no need for the network layer. The network layer divides the segments that come from the transport layer. These are referred to as packets. The division of the segments into packets happens on the sender’s device, and they are reassembled on the receiving device.

The network layer also functions as an efficiency tool. It figures out the optimal physical path needed to get the data to its destination. This function is called “routing.”

Layer 2 - Data Link Layer

The data link layer is like the network layer, except that the data link layer facilitates data transfer between two devices using the same network. In the data link layer, packets are broken into pieces referred to as frames. Similar to the network layer, the data link layer handles flow and error control. The transport layer is different in that it only manages the flow of data and errors when two networks are communicating with each other.

Within the data link layer, you have two sublayers, the media access control (MAC) and logical link control (LLC) layers. The majority of switches perform their duties at Layer 2. In some cases, switches work at Layer 3 because they are facilitating communication between two networks or virtual local-area networks (VLANs). This has to happen at Layer 3 because, in these situations, the data needs to be routed, which is a Layer 3 task.

Layer 1 - Physical Layer

The physical layer involves the physical equipment that transfers data, like switches and cables. In this layer, the data is converted into strings of 1s and 0s. In the physical layer, the devices have to agree on a method of distinguishing the 1s from the 0s, which enables the digital data to be properly interpreted by each device.

The physical layer includes a variety of components, such as cables, the radio frequency used to transmit data, Wi-Fi, and the other physical structures for transmitting data, such as pins, necessary voltages, and types of ports.

How data flows through different OSI Model Layers

Each of the seven OSI model layers communicates with layers below and above it. For example, the application layer interacts with software applications, while the presentation layer provides encryption and data compression. Likewise, the session layer creates communications between devices. The transport layer breaks data into chunks (called segments) to send them, then the receiving device reassembles the segments before the network layer breaks them into smaller packets to send to other networks. The data link layer facilitates data transfer between devices on the same network, and, finally, the physical layer transfers data in machine language (ones and zeros).

How Fortinet Can Help

Firewalls typically work on the network layer, the transport layer. However, some are also capable of working as high as the application layer, Layer 7.

A firewall performs the task of inspecting network activity, looking for cyber threats by comparing data against an extensive catalog of known threats. They can also detect abnormal activity, which may signal a potential threat. Layers 4 and 7 are optimal locations for intercepting data and inspecting its contents, as is Layer 7 if the activities of an application are of interest.

FortiGate  firewalls performs functions at Layers 3 (network), 4 (transport), and 7 (application. At Layer 3, FortiGate sits between two interconnected networks. As data is transmitted from one network to the other, FortiGate performs in-depth packet inspection, checking whether the connection is being used to send cyber threats.

At Layer 4, FortiGate is positioned between two devices, inspecting each data segment before it reaches the receiving device. In this way, FortiGate prevents one device from being used to infect another. FortiGate also interacts with Layer 7 in that it has the ability to inspect the behavior of an application, including how it uses its data resources. At Layer 7, FortiGate can detect suspicious activity within the application and act accordingly.

FortiGate can identify the source, position, and content of the data, comparing it against a constantly evolving collection of threat signatures. If something suspicious is detected, the data can be discarded before it infects the receiving device.

Frequently Asked Questions about OSI Model

1. what is osi model, 2. why do we use the osi model, 3. what are 7 layers of the osi model.

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Presentation layer in osi model.

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Last Updated on March 7, 2024 by Abhishek Sharma

presentation layer function in networking

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.

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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.

presentation layer

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.

duplex modes

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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presentation layer function in networking

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Presentation Layer

Last Edited

What is the Presentation Layer?

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

Presentation Layer

Presentation Layer functions

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

Role of Presentation Layer in the OSI Model

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

Explaining Layer 6 in video

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

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

However, HTTP includes presentation layer services within it. HTTP works when the requesting device forwards user requests passed to the web browser onto a web server elsewhere in the network.

It receives a return message from the web server that includes a multipurpose internet mail extensions (MIME) header. The MIME header indicates the type of file – text, video, or audio – that has been received so that an appropriate player utility can be used to present the file to the user.

In short, the presentation layer

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

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

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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OSI Network Model 7 Networking Layers

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In this article, we will discuss OSI Network Model Layers. We use 7 networking layers of the OSI Model (Open System Interconnected Model) to understand how one computer transfers data to another in a computer network.

Networking 7 layers or Open Systems Interconnect (OSI) model is a conceptual framework that describes networking or telecommunications systems as seven layers (i.e., OSI network model layers), each with its function. Let’s read below “OSI Network Model 7 Networking Layers”:-

What are the advantages of the OSI Network Model 7 Networking Layers?

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

In the most basic form, two computers connect with LAN cable and connectors and share data with the help of network interface cards form a network. But if one computer is based on MS Windows and the other has Mac OS installed, how will these computers communicate with each other? The 7 networking layers and OSI model or open system interconnected model was introduced by the International Organization for Standardization in 1984. It was to accomplish successful communication between computers and networks of different architectures. There are the following OSI Network Model Layers;

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

Note that each layer is a package of protocols.

Protocols and Devices used at various layers of the OSI Model

1- Application Layer

Definition of application layer.

An application layer of OSI is an abstraction layer that specifies the shared communications, protocols, and interface methods used by hosts in a communications network. However, the Internet Protocol Suite (TCP/IP) and the OSI model specify an application layer abstraction. Although both models use the same term for their highest-level layers, the detailed definitions and purposes differ.

Explanation

Application layer does not mean that it includes computer applications like Chrome, Firefox, etc. But it provides application layer protocols to make these applications work correctly in a network or the internet.

The Application Layer is the top layer of networking. Network applications use the Application layer. “Network application means computer applications that use the internet like Chrome, Firefox, Skype, etc.”

The web browser is a network application running on your PC, it does not reside in the application layer, but it uses application protocols like “HTTP” or “HTTPS” to do web surfing. Web browsers and all network applications, including outlook, skype, etc., depend on application layer protocols to function.

Dozens of application layer protocols enable various functions at this layer. However, all these protocols collectively form an application layer. These protocols form the basis for network services like file transfer, web surfing, email, and virtual terminals. For Examples: HTTP, HTTPS, FTP, NFS, FMTP, DHCP, SNMP, TELNET, POP3, IRC & NNTP etc.

A machine does file transfer with ‘FTP’ protocol, surfs the web with the help of ‘HTTP or HTTPs’ protocol, and uses telnet for virtual terminals. So the application layer provides services for network applications with the help of protocols to perform user activities.

Most commonly, a question arises, which application layer protocol is used by electronic mail? Simple Mail Transfer Protocol (SMTP) is an application layer protocol to transmit electronic mail.

2- Presentation Layer

The presentation layer description is that; this layer is also known as the Translation layer, which serves as a data translator for the network. This layer receives the data from the Application Layer and extracts and manipulates it here as the required format to transmit over the web. The primary responsibility of this layer is to provide or define the data format and encryption. The presentation layer is also called the Syntax layer since it is responsible for maintaining the proper syntax of the data it receives or transmits to other layers.

The presentation layer functions as follows;

  • It serves network security and confidentiality management, text compression and packaging, and virtual terminal protocol (VTP).
  • Syntax conversion – The abstract syntax is converted to the transfer syntax. The other side achieves the opposite transformation (It converts transfer syntax to abstract syntax). It is involved in the contents of the code conversion, character conversion, data format modification, data structure operation adaptation, data compression, encryption, and so on.
  • Grammar negotiation: According to the application’s requirements, layer to negotiate the appropriate choice of context, that is, to determine the transmission syntax and transmission.
  • Connection management – Including the use of the session layer service to establish a connection, manage data transport and synchronization control over this connection (using the related services at the session level), and terminate the connection either normally or absently.

The presentation layer of the OSI model receives data from the ‘Application Layer.’ This data is in the form of characters and numbers. It converts these characters and numbers to machine-understandable binary format. For Example, conversion of ASCII to FCD code. This function of the presentation layer is called ‘translation.’ Before data transmission, the presentation layer reduces the number of bits used to represent the original data. This bit reduction process is called ‘data compression and can be lossy and lossless.

Data compression reduces the amount of space that a device uses to store the original file since it reduces the size of the file. It can be received at the destination in less time so that data transmission can be done faster. Thus, data compression is beneficial in real-time video and audio streaming.

Encryption enhances the security of sensitive data. A network uses “SSL Protocol or Secure Socket Layer Protocol” in the presentation layer for encryption and decryption. This layer encrypts the data to maintain its integrity of data before transmission. On the sender side, data is encrypted, and on the receiver side, it is decrypted.

So the Presentation layer Performs three primary functions, i.e., Translation, Compression, and Encryption & Decryption.

Protocols in Presentation Layer

Presentation layer protocols are as follows;

  • 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, The Tox protocol is sometimes regarded as part of the presentation and application layer.
  • eXternal Data Representation (XDR)
  • 25 Packet Assembler/Disassembler Protocol (PAD)

3- Session Layer

What is the session layer of the osi model.

The answer to this question is Session Layer is the layer of the ISO Open Systems Interconnection (OSI) model that controls the dialogues (connections) between computers. It establishes, manages, and terminates the connections between the local and remote applications. Moreover, it provides full-duplex, half-duplex, or simplex operation and establishes check-pointing, adjournment, termination, and restart procedures. The OSI model made this layer responsible for:

  • graceful close of sessions, a property of the Transmission Control Protocol,
  • Session check-pointing and recovery are not usually used in the Internet Protocol Suite.

The session layer is commonly implemented explicitly in application environments that use remote procedure calls.

Purpose of Session Layer

Suppose you have planned a party and hired a few helpers, ensuring that each activity runs smoothly. Helpers will help you set up, assist, clean, and close the party. The same is the case with the Session layer. Session layers help set up and manage connections, enabling sending and receiving of data followed by termination of connections or sessions like you hired some helpers for your party.

The session layer has helpers called ‘APIs or Application Programming Interfaces. NETBIOS (Network Basic Input and Output System) is an example of APIs. It allows applications on different computers to communicate with each other just before a session or a connection establishes with the server. The server performs a function called authentication.

Authentication is a process of verifying who you are. This server uses a username and password. Once entered, the username and password match a session. Then a connection gets established between your computer and the server.

After authenticating, the system checks the user authorization. Authorization is a server’s process to determine if you have permission to access a file. If you don’t have accessibility, you will get a message saying, “You are not authorized to access this page”.

The session layer performs both these functions, i.e., authorization and authentication.

The session layer keeps track of files that we are downloading. For Example, a webpage contains texts, images, etc. It stores these texts and images as separate files on the web server. When you request a website in your web browser and open a different session to the webserver to download each text and image file separately, you receive these files as data packets. The session layer keeps track of which data packet belongs to which file, either a text or an image file, and tracks where the received data packet goes.

In this case, it goes to the web browser, a session layer that helps in session management. Your web browser performs all functions of the session, presentation, and application layer. So the session layer helps in session management authentication and management.

An example of a session layer protocol is the OSI protocol suite session-layer protocol, also known as X. 225 or ISO 8327

4- Transport Layer

Transport Layer controls the reliability of communication through

  • Segmentation,
  • Flow control and
  • Error control.
  • Segmentation

In segmentation, the transport layer receives the data from the session layer and divides it into small data units called segments. Each segment contains a source and destination port number and a sequence number.

Port Number helps direct each segment to the correct application, and Sequence Number helps reassemble pieces to form the right message at the receiver.

Flow Control

In Flow Control, the transport layer controls the amount of data transmitted. Consider our mobile connects to a server. Suppose the server can send data maximum at 100 Mbps, and our mobile can process data maximum at 10 Mbps.

Let’s suppose we are downloading a file from the server, but the server starts data at 50 Mbps, which is greater than the rate our mobile can process. So a mobile phone, with the help of a transport layer, can tell the server to slow down the data transmission rate up to 10 Mbps so that no data gets lost. Similarly, if the server sends data at 5 Mbps, the mobile phone tells the server to send the data up to 10 Mbps to maintain system performance.

Error Control

The transport layer also helps in error control if some data does not arrive at the destination. It uses automatic repeat request schemes to re-transmit the lost, corrupted data. The transport layer adds a group of bits called “checksum” to each segment. It is to find out whether received corrupted segment protocols of transport layers are transmission control protocols (TCP) and user datagram protocols (UDP).

Services of TCP

The transport layer performs two types of services, i.e., connection-oriented transmission and connectionless transmission.

  • Connection-oriented transmission is done via TCP.
  • Connectionless transmission is done via UDP.

UDP works faster than TCP. It does not provide feedback on whether data gets delivered, whereas TCP offers input. Therefore, we can re-transmit the lost data in TCP. We use UDP, where it does not matter whether we have received all data. For Example, Online streaming of movies, songs, games voice-over, IP, TFTP, DNS, etc.

On the other hand, we use TCP, where entire data delivery is a must—for Example, the world wide web, email, FTP, etc. So Transport layer performs the following functions;

  • Connection-Oriented And
  • Connectionless Transmission

5- Network Layer

The transport layer of the OSI model Passes the data segments to the network layer. The network layer works to transmit the received data segments from one computer to another located in different networks.

Data units in the network layer are called Packets. It is the layer where the router recites.

1- Logical Addressing

“IP Addressing done in a logical layer is called logical addressing.”

Every computer on a network has a unique IP Address. Moreover, the network layer assigns the sender and receiver’s IP addresses to each segment to form IP Packet.

A network assigns IP addresses to every device to ensure that each data packet can reach the correct destination.

Routing is a method of moving data packets from source to destination based on the logical address format of IPV4 or IPV6.

For Example: Suppose that computer A connects to network no. 1 and computer B connects to network no. 2. From computer B, we have requested to access facebook.com. And now, there is a reply from the Facebook server for computer B in the form of a packet. This packet needs to be delivered to computer B only since, in a network, each device has a unique IP address. The network layer of the Facebook server has already added the sender and receiver’s IP addresses in the packet. So both these computers have unique IP addresses as well.

Suppose the mask used is 225.225.225.0. This mask tells that the first three combinations represent a network while the last combination represents a host or computer b. So based on the IP address format, the received data packet will move first to the second network and then to computer B. So based on IP address and mask, we make routing decisions in a computer network.

3- Path Determination

There are several ways to connect a computer to an internet server. Path determination is the best path for data delivery from source to destination. Layer 3 devices use protocols such as open shortest path first, border gateway protocol, and intermediate system to intermediate system to determine the best possible data delivery method.

6- Data Link Layer

Data Link Layer is the second layer among the OSI network model layers. This layer is one of the most complicated and has complex functionalities and liabilities. Moreover, the data link layer hides underlying hardware details and represents itself to the upper layer as the communication medium.

The data link layer works between two hosts, which directly connect in some sense. This direct connection could be point-to-point or broadcast. Systems on a broadcast network are said to be on the same link. The work of the data link layer tends to get more complex when dealing with multiple hosts on a single collision domain.

The data link layer is responsible for converting the data stream to signals bit by bit and sending that over to the underlying hardware. Furthermore, at the receiving end, the Data link layer picks up data from hardware in the form of electrical signals, assembles them in a recognizable frame format, and hands them over to the upper layer.

The data link layer has two sub-layers:

Logical Link Control: It deals with protocols, flow control, and error control.

Media Access Control: It deals with the actual control of media.

The functionality of the Data-link Layer

The data link layer does many tasks on behalf of the upper layer. These are:

Data-link layer takes packets from Network Layer and encapsulates them into Frames. Then, it sends each frame bit-by-bit on the hardware. At the receiver’s end, the data link layer picks up signals from hardware and assembles them into frames.

Data-link layer provides a layer to the hardware addressing mechanism. However, it assumes that the hardware address is unique on the link. At the time of manufacturing, it encodes into hardware.

Synchronization

Both machines must be synchronized for transfer when data frames are sent on the link.

Sometimes signals may encounter problems in transition, and the bits get flipped. Therefore we have to detect these errors and attempt to recover actual data bits. It also provides an error reporting mechanism to the sender.

Stations on the same link may have different speeds or capacities. Data-link layer ensures flow control that enables both machines to exchange data at the same rate.

Multi-Access

When a host on the shared link tries to transfer the data, it has a high probability of collision. Data-link layer provides a mechanism such as CSMA/CD to equip the capability of accessing a shared media among multiple Systems.

7- Physical Layer

The physical layer is the bottom-most layer in the OSI network model layers, a physical and electrical representation of the system. It consists of various network components such as power plugs, connectors, receivers, cable types, etc. The physical layer sends data bits from one device(s) (like a computer) to another device(s). It defines the encoding types (that is, how the 0’s and 1’s are encoded in a signal). The physical layer is responsible for communicating the unstructured raw data streams over a physical medium.

The essential and basic functions of the Physical Layer of the OSI Model are as follows:

  • The physical layer maintains the data rate (how many bits a sender can send per second).
  • It performs Synchronization of bits.
  • It helps in the Transmission Medium decision (direction of data transfer).
  • Moreover, it helps in the Physical Topology (Mesh, Star, Bus, Ring) decision (Topology through which we can connect the devices).
  • It helps in providing Physical Medium and Interface decisions.
  • It offers two types of configuration: Point to Point configuration and Multi-Point configuration.
  • It provides an interface between devices (like PCs or computers) and the transmission medium.
  • It has a protocol data unit in bits.
  • The instruments used in this layer are Hubs, Ethernet, etc.
  • This layer comes under the category of Hardware Layers (since the hardware layer is responsible for all the physical connection establishment and processing too).
  • It provides an important aspect called Modulation, which converts the data into radio waves by adding the information to an electrical or optical nerve signal.
  • It also provides a Switching mechanism wherein one can forward data packets from one port (sender port) to the leading destination port.

Physical Topologies

We have discussed all 7 networking layers, i.e., OSI network model layers. Now, we will talk about network topologies that fall under the physical layer domain of OSI Network Model Layers. Physical Topology of Network Topology is the Geographical Representation of Linking devices. Following are the four types of physical topology:

Mesh Topology

Mesh Topology is challenging to install because it is more complex. Each device should have a dedicated point-to-point connection with another device in the network in a mesh topology. Here there is more data security because there is a reliable point-to-point connection between two devices.

Star Topology

Star Topology is easy to install and reconnect as compared to Mesh Topology. In star topology, the device should have a dedicated point-to-point connection with a central controller or hub. Star Topology doesn’t have a Fault Tolerance Technique.

Bus Topology

In a bus topology, multiple devices connect through a single cable known as the backbone cable with the help of tap and drop lines. It is less costly as compared to Mesh Topology and Star Topology. Re-connection and Re-installation are difficult.

Ring Topology

Each device connects with repeaters in a circle-like ring in this topology. Therefore, we call it Ring Topology. In-Ring topology, a device can only send the data with a token. No machine can send the data without a permit, and Monitor places a token in Ring Topology.

We have done all about OSI Network Model Layers. Moreover, you may read about the Modes of Communication in Computer networks. I hope you like reading “OSI Network Model 7 Networking Layers”.

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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

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!

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  1. Presentation Layer in OSI model

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  2. Presentation layer

    In the seven-layer OSI model of computer networking, the presentation layer is layer 6 and serves as the data translator for the network. It is sometimes called the syntax layer. Description. Within the service layering semantics of the OSI network architecture, the presentation layer responds to service requests from the application layer and ...

  3. The OSI Model

    Chloe Tucker. 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.

  4. 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 ...

  5. 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.

  6. Presentation Layer of the OSI Model: Definition and Function

    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 functions necessary for this transmission. This can even occur between computers or networks of ...

  7. Presentation Layer of the OSI Model

    Presentation layer: The OSI presentation layer is the sixth layer and translates data across the network. Application layer: Topmost seventh layer which stipulates the interface methods for the ...

  8. What is the OSI Model? 7 Network Layers Explained

    The presentation layer also compresses data that comes from the application layer before it sends it on to Layer 5, the session layer. ... The network layer also functions as an efficiency tool. It figures out the optimal physical path needed to get the data to its destination. This function is called "routing."

  9. 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 ...

  10. 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.

  11. Presentation Layer

    The network redirector also functions at this layer. Presentation Layer. Presentation Layer functions. Translation: Before being transmitted, information in the form of characters and numbers should be changed to bit streams. Layer 6 is responsible for interoperability between encoding methods as different computers use different encoding methods.

  12. 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:

  13. 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 ...

  14. 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.

  15. 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 ...

  16. 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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    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 ...

  18. OSI Network Model 7 Networking Layers

    The presentation layer is also called the Syntax layer since it is responsible for maintaining the proper syntax of the data it receives or transmits to other layers. Functions. The presentation layer functions as follows; It serves network security and confidentiality management, text compression and packaging, and virtual terminal protocol (VTP).

  19. networking

    The session layer is meant to store states between two connections, like what we use cookies for when working with web programming. The presentation layer is meant to convert between different formats. This was simpler when the only format that was worried about was character encoding, ie ASCII and EBCDIC. When you consider all of the different ...

  20. Presentation Layer: Protocols, Examples, Services

    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.

  21. Presentation layer definition

    Presentation layer definition. The presentation layer is the sixth layer in the Open System Interconnection (OSI) model. It serves as the data translator for the network — it takes data formats from different sources and presents it to the application layer in an accurate, well-defined, and standardized manner. Real presentation layer functions