What is the ISO?
The ISO stands for International Stranded Organization, establish in 1947. That is multinational company to word wide agreement on international stranded and ISO stranded that cover all aspects of network communication is the OSI mode.
What is OSI Model?
OSI stands for Open System Interconnection. In this model we use different layers for transfer of data using multiple protocols at a time. Combining several protocols each with their own dedicated purpose is not easy hence the concept of layered structure was developed to help keep each protocol in its place and to define the manner of interaction between each protocol. The data sent between layers is called a services data unit (SDU) so OSI defines the analogous (similar) data between two machines (systems) as a protocol data unit (PDU). For the purpose of quick result we divide the work between different groups, similarly with open system interconnection, one group deals with the transport of data, another with the packaging of messages, another with end-use application, and so on. Each group of related tasks is called Layer. The Open System Interconnection Reference Model (OSI-RM) uses seven layers. The TCP/IP architecture is similar but involves only five layers because it combines some of the OSI functionality in two layers into one. The three layer i.e. application layer, presentation layer and session layer are called Upper Layers. These all layers are independent. The next four layers are called lower layers.
THE OSI MODEL
OSI stand for open system Interconnection. The OSI model is layers. The ISO standard for worldwide communications that defines a networking framework for implementing protocols in seven layers, control is passed from one layer to the next starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy. That allows for communication across all types of computers systems. It consists of seven layers.
1. Application layer
2. Presentation layer
3. Session layer
4. Transport layer
5. Network layer
6. Data link layer
7. Physical layer
What are the OSI seven layers?
1. Application layer
2. Presentation layer
3. Session layer
4. Transport layer
5. Network layer
6. Data link layer
7. Physical layer
Application Layer
The application layer enables the user withers human and software to access the network. It provides user interface and support for services for example: email, remote file access and transfer and share the data pose management. The application layer is the end-user interface of the OSI model. It is where the application such as electronic mail, newsreaders, or database displays models. The application layer’s task is to display received information and send the user’s new data to the lower layers. It communicates through the lower to the server.
Presentation Layer
The presentation layer is considering with the syntax and semantics of information Exchange between two systems. The presentation layer convert the data from the application into a common format it processes the machine-dependent data from the lower layers. The presentation layer is where file formats and even character formats are lost. This layer reverses for incoming data. It is converted from the common format into application specific formats based on the types of application.
Session Layer
The session layer services provided by the first three layers physical, data link and networks are not sufficient for some process. The session layer is the network dialog controller. It establishes and maintains the interaction between communicating system. The work of Session Layer is that organizes the exchange of data between application processes. It works with the application layer to provide simple data sets called Synchronization (management) Points that let an application know how the transmission and reception of data are progressing. In simple words the session layer is known as a timing and flow control layer. It involved in co-ordination communications between different applications, letting each know the status of the other.
Transport Layer
The transport layer is represents able for source to destination delivery of the entire message it dose not recognize any relationship between packets. The transport layer as its name suggest is designed to provide the Transport transfer of data a source and open system to a destination end open system. Regarding the OSI references model the transport layer establishes maintains and terminates communications between two machines (system). The transport layer is responsible for ensuring that data sent and received correctly. It not only manages the sending of data but also determining its order and its priority.
Network Layer
The network layer is responsible for the source to destination delivery of a packet. Possibly across multi networks, were as data link layer oversees the delivery of Packet between two systems on the same network. The same Network layer insures that each packets gets from its point of origin to its final destination. The network layer provides the physical routing of the data, determining the path between the machines (systems). The network layer handles all these routing issues and examines the network topology to determine the best route to send a message. It is only layer that sends a message from source to target system.
Data Link Layer
The data link layer is a new transmission to a relay able link and is response able for node-to-node delivery. The Data Link Layer regarding the OSI provides for the control of the physical layer, detects and possibly correct errors that can occur. It responsible for usually concerned with signal interference on the physical transmission media.
Physical Layer
The physical layer coordinates the physical medium. It deals with the mechanical and Electrical specification of interface and transmission. It also defines the progress and function that physical devices and interface have to perform for transmission to Acer. The physical layer is the lowest layer of the OSI model with the Mechanical, Electrical, Functional and Procedural means required for transmission of data. This is really the wiring or other transmission form.
No comments:
Post a Comment