...OSI Seven Layer Model The Open System Interconnection model (OSI) defines internetworking in terms of a vertical stack of seven layers. The upper layers of the OSI model represent software that implements network services like encryption and connection management. The lower layers of the OSI model implement more primitive, hardware-oriented functions like routing, addressing, and flow control(Mitchell, 2011).The seven layers of the OSI model are - * Physical * DataLink * Network * Transport * Session * Presentation * Application Physical Layer is the first layer of the OSI model and deals with the physical aspects of the media being used to transmit the data. This layer is also responsible for bit-level transmission between network nodes. Specification examples include Ethernet, 802.3, 802.5, and Fiber Distributed Data Interface. Data Link Layer is the second layer of the OSI model and is responsible for ensuring there are data link connections between two network entities so that data can get across a specific medium and individual links. Examples of this layer include IEEE 802.3, IEEE 802.5, Token Ring, and Frame Relay. Network Layer is the third layer of the OSI model and is responsible for the packet sequencing, congestion control, and error handling. This layer also provides paths for data to transfer through the network. At the Network layer routers began to operate. Examples of this layer include the use of Internetwork Protocol (IP)...
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...Papers The OSI Model: Understanding the Seven Layers of Computer Networks 1-800-COURSES www.globalknowledge.com The OSI Model: Understanding the Seven Layers of Computer Networks Paul Simoneau, Global Knowledge Course Director, Network+, CCNA, CTP Introduction The Open Systems Interconnection (OSI) model is a reference tool for understanding data communications between any two networked systems. It divides the communications processes into seven layers. Each layer both performs specific functions to support the layers above it and offers services to the layers below it. The three lowest layers focus on passing traffic through the network to an end system. The top four layers come into play in the end system to complete the process. This white paper will provide you with an understanding of each of the seven layers, including their functions and their relationships to each other. This will provide you with an overview of the network process, which can then act as a framework for understanding the details of computer networking. Since the discussion of networking often includes talk of “extra layers”, this paper will address these unofficial layers as well. Finally, this paper will draw comparisons between the theoretical OSI model and the functional TCP/IP model. Although TCP/IP has been used for network communications before the adoption of the OSI model, it supports the same functions and features in a differently layered arrangement. An Overview of the OSI Model ...
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...The network layer provides a mechanism called routing to achieve this. • Network layer includes services such as error control, packet sequence control and flow control. • Splits large packets into smaller ones. iv. Transport Layer This layer is concerned with functions related to the reliable and unreliable delivery of data from source to destination. Transport layer splits data into smaller packets as soon as data is sent by a computer on a network so that packets can be resent if any of them fail to reach the specified destination. The transport layer provides transparent data transfer between the end devices and controls flow of packets. This layer is responsible for ensuring complete data transfer and for the end-to-end error recovery. Transport layer transmits whole data in the predefined order and ensures flow control and error control during transmission of data from source to destination. Figure 1.2.6: Transport Layer Source: http://www.studytonight.com/computer-networks/osi-model-transport-layer Functions of Transport...
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...Open Systems Interconnect model (OSI), which developed by the International Organization for standardization (ISO), it is the most popular model, it provides a framework for the design of the network systems and it illustrates how the systems work as reported by Frenzel (2013). TCP/IP and OSI are two of the most important hierarchical models; they are very useful because they help us to understand a lot of the difficult terminologies and systems. They have some rules that control the communication process with each other. When the OSI standards published, the TCP/IP was in the development phase. The OSI was very impressive in the growth of TCP/IP standards, and it is very common to see the TCP/IP using the terminologies of the IOS, because there are many similarities between the goals of TCP/IP and OSI (Frenzel,...
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... Expert Reference Series of White Papers The OSI Model: Understanding the Seven Layers of Computer Networks 1-800-COURSES www.globalknowledge.com Pg2Pg2 The OSI Model: Understanding the Seven Layers of Computer Networks Paul Simoneau, Global Knowledge Course Director, Network+, CCNA, CTP Introduction The Open Systems Interconnection (OSI) model is a reference tool for understanding data communications between any two networked systems. It divides the communications processes into seven layers. Each layer both performs specific functions to support the layers above it and offers services to the layers below it. The three lowest layers focus on passing traffic through the network to an end system. The top four layers come into play in the end system to complete the process. This white paper will provide you with an understanding of each of the seven layers, including their functions and their relationships to each other. This will provide you with an overview of the network process, which can then act as a framework for understanding the details of computer networking. Since the discussion of networking often includes talk of “?extra layers”?, this paper will address these unofficial layers as well. Finally, this paper will draw comparisons between the theoretical OSI model and the functional TCP/IP model. Although TCP/IP has been used...
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...The OSI Model Upon trying to decide what to write about, I decided to go with The Open System Interconnection or OSI Model for short. My reasons are simple. One, the OSI Model provides a ton of information to write about. Secondly, found it to be one of the most interesting topics. My objective is to obviously explain the different layers of the OSI Model. As well as how communication occurs, and the many other functions of the Model. The OSI Reference model is based on a proposal developed by the International Standards Organization (ISO). The original objective of the OSI model was to provide a set of design standards for equipment manufactures so they could communicate with each other. The OSI model defines a hierarchical architecture that logically partitions the functions required to support system-to-system communication. “The OSI model is a theoretical representation of what happens between two nodes communicating on a network.” (Network + Guide to Networks fifth edition) It goes on say “It does not prescribe the type of hardware or software that should support each layer. Nor does it describe how software programs interact with humans.” The communication in the model is defined by its seven layers, which divides the tasks into seven smaller components that can be easily managed. A task or group of task are assigned to each layer and each layer is reasonably self- contained so that the task assigned to each layer can be managed and updated independently. My...
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...Describe the OSI Model and how it relates to a network. The OSI Reference Model is becoming more popular everyday because it is a useful tool for learning about networks. The OSI Reference Model is where the communication system (network) is broken down into seven layers, where each layer serves a purpose. The OSI Reference Model defines what each layer’s function is but does not specify actual services in the layers. So that the vendors can write device drivers for a device; and not be concerned about the higher layers, this speeds up the process. The seven layers are divided into three groups: 1) Application (upper) layer, 2) Intermediate layer, 3) and Network oriented (lower) layer. With this system the OSI Reference Model is convenient because you’re able to communicate with a different computer network. The WAN Network operates on the Physical and data link layer of the OSI Reference Model. What are some Protocols? The purpose of the OSI Reference Model is to determine how data should be transmitted between two points in a network. Its job is to consistently work with other products. On which layer do switches and routers operate? Layer two, three, and four the Presentation layer, Session, and Transport Layer is where the witches and routers will operate. If Routers operate on more than one layer, what is the difference? Routers operate on layer three then apply on layer two and the switch the packets. Layer two would be Ethernet and layer three is the operating...
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...500 WORD What is the OSI model the 7 layers The Open Systems Interconnection or (OSI model) “Is an architectural model that represents networking communication. It was introduced in 1978 by the International Organization for Standards to standardize the level of services and types of interactions for computers communicating over a network” (Emdad). The OSI is the standard that sets the path that data must travel through from one computer to another through a network. The OSI does this by the sending the through seven different layers almost like sending the data through checkpoints and at each checkpoint the data must be cleared so it is able to move on to the next stop. This is what the seven layers of OSI do. The data must go each layer, each layer performs a specific task in order to pass the data through to the next layer, and these layers also communicate to the layer above and below to make sure that everything in order. There are seven layers and each one has a specific function that prepares it for next layer the data must pass through all seven layers. The layers are separated into two sets the first is the application set • Application layer 7- This is the layer that provides the interface between the network protocol and the software running on the computer. This layer handles anything that communicates with the internet; this layer also handles any network related activity such as file transfers or reading and sending email. This layer is the closest one to...
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...OSI Model Protocol The OSI (Open Systems Interconnection) model is a logical plan that explains network interactions used by a system open to interconnection and communicate with other systems. The objective of the OSI model is to directly product implementers so that the items will frequently work with the other items. The OSI model is broken into seven layers, each of which presents a collection of services above and below it. The OSI is also of use in a training environment where a novice can use as a guide to source to understand how technologies communicate, where they reside, what functions they will perform and how protocol interacts with other protocols Briscoe, N. (2000). The primary objective of the OSI model is that the communication between the end points in networks can be separate into different levels with every level having its duties. An OSI determines how the data will flow down the seven layers at the sending end, and how it will move up through the layers at the location end of communication development. The seven layers of the OSI are the physical layer, data-link layer, network layer, transport layer, session layer, presentation layer and the application layer. A physical layer also uses bits as its PDU, which are e-signals represented in digit 1s and 0 Briscoe, N. (2000). The top four levels are used when a message is being transmitted from one user to another user. The lower three levels are practiced when a message is passing through...
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...Interconnection or OSI is a standard for computer communications that defines a networking framework for protocols that is set in seven layers. When a computer begins a transmission data is passed from one layer to the next, starting at the application layer in one computer, flowing to the bottom layer being the physical layer, over to the next computer and back up the seven layers. At one time, most vendors created their own standards to get companies to only use their computers in one form or another, because the OSI was too loosely defined so proprietary standards were the norm. Now the OSI model functionality exists in all communications systems. How Information flows through the OSI In the OSI model information is transmitted through the seven layers. The sending process passes data to the application layer. The application layer attaches a header and then passes the frame to the presentation layer. The presentation layer can transform data in different ways, by translating it and adding a header. It gives the result to the session layer. The presentation layer doesn’t know what part of the data it received from the application layer because that information is not important to the presentation layer's role. The process of adding headers is repeated from layer to layer until the frame reaches the data link layer. There, in addition to a data-link header, a data-link trailer is added this helps the synchronization of the data. The data is then passed down to the physical layer, where...
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...THE OSI REFERENCE MODEL The concept of how a modern day network operates can be understood by dissecting it into seven layers. This seven layer model is known as the OSI Reference Model and defines how the vast majority of the digital networks on earth function. OSI is the acronym for Open Systems Interconnection, which was an effort formed by the International Organization for Standardization in 1982 with the goal of producing a standard reference model for the hardware and software connection of digital equipment. The important concept to realize about the OSI Reference Model is that it does not define a network standard, but rather provides guidelines for the creation of network standards. The OSI has become so accurate a concept that almost all major network standards in use today conform entirely to it's seven layer model. Though seven layers may at first appear to make a network seem overly complex, the seven layer OSI Model has been proven over the past twenty years to be the most efficient and effective way to understand this extremely complex subject. OSI LAYER 1: THE PHYSICAL LAYER The first and foundational layer of a network is the Physical Layer. The Physical Layer is literally what it's name implies: the physical infrastructure of a network. This includes the cabling or other transmission medium and the network interface hardware placed inside of computers and other devices which enable them to connect to the transmission medium. The purpose of the Physical...
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...and OSI Layers TCP/IP Architecture and OSI Layers [your name here] NTC360 Network and Telecommunications Concept Associate Professor Anthony Bruno January 04, 2011 The purpose of this paper is to describe an OSI (Open Systems Interconnection) Model with details about each of the seven layers. The OSI reference model adopts a layered approach, where a communication subsystem is broken down into seven layers, each one of which performs a well-defined function. Additionally it is important to understand the purpose of the OSI model in the overall networking architecture especially as it relates to the TCP/IP (Transmission Control Protocol/Internet Protocol) Architecture, which also consists of layers each playing a particular role in the networking design. Generally speaking, the network protocol layer, which is similar to the data and network layer of the OSI model includes the protocols that allow clients and applications to send data over the network. This includes TCP/IP, NWLink (IPX/SPX), NetBEUI, Infrared Data Association (IrDA). However, the purpose of this document is to focus on the relationships between the OSI model and the TCP/IP architectures, and how they may interact together. Finally, as demonstration of this relationship a visual diagram has been provided to depicts how the TCP/IP layers correspond to the OSI model and layers. To begin with, it is important to understand the seven different layers of OSI...
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...Material Appendix C OSI Model Key Terms Table Use the table to define the key terms related to the OSI Model. Describe the functions of any hardware connectivity devices and tools listed. . | | |Function | |Term |Definition |(if applicable) | |Physical layer |This is the first and lowest layer in the |This is when the data is sent on the | | |seven-layer OSI model. |network media by the NIC. | |Data link layer |This is layer two of the OSI model and |The Data link layer is responsible for | | |resides above the Physical Layer and below |communications between adjacent network | | |the Network Layer. |nodes. | |Network layer |The Network Layer is layer three of the OSI|The Network Layer is responsible for | | |model and resides above the Data Link Layer|establishing paths for data transfer | | |and below the Transport Layer. |through...
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...Department of Defense adopted TCP/IP as the standard for military computer networking. Layers- Compared to the Open Systems Interconnection (OSI) model, the TCP/IP model has fewer layers. It uses encapsulation to provide abstraction of protocols and services. The Application layer is at the top and is logically closer to the user. This is where applications create the user data and communicate that data to other applications. The Transport layer provides the host to host communications, creating a channel for the communication needs of the applications. The Internet layer is where the datagrams are exchanged across the network. The Link layer serves to define the networking method, and includes the protocols describing the network topology. Now, compare this with the Open Systems Interconnection (OSI) model and its seven layers, wherein each layer facilitates the needs of the layer above it, while calling on the next layer below it. This model evolved from work with ARPNET, as well. This chart shows the four layers of the TCP/IP model, showing the basic flow of information from user, via applications, to another user. I like this model for its simplicity in form and functionality. Here is a chart showing the Open Systems Interconnection (OSI) model and its seven layers. This illustrates the flow of datagram packets from user to user and the addition of headers as it passes through each layer. This is a side by side illustration, comparing the...
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...| Internetworking | Submitted By: Courtney White Submission Date: 11/20/2012 Submitted To: Professor Conn Assignment 4 An internetwork is an assortment of distinct networks that functions as a single large network. Internetworking denotes to the industry, products, and procedures that meet the challenge of crafting and governing internetworks. (Corner & Stevens, 1952) The first networks were time-sharing networks that used mainframes and attached terminals. Local-area networks progressed around the PC insurrection. (Davidson & Muller, 1992) LANs allowed numerous operators in a somewhat trifling area to interchange files and messages, as well as access shared resources. Wide-area networks interconnect LANs with geographically disseminated users to create connectivity. (Davidson & Muller, 1992) Though it is quite simple to visualize internetwork, implementing a practical internetwork is no unpretentious job. Many encounters must be tackled, especially in the areas of connectivity, reliability, network management, and flexibility. Each area is plays a key role in inaugurating a proficient and operative internetwork. The test when connecting various systems is to support communication among disparate technologies. Different sites, for example, may use different types of media operating at varying speeds, or may even include different types of systems that need to communicate. Because establishments depend comprehensively on data communication, internetworks...
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