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OSI Model (contd ...)

 Transport layer

The transport layer provides the flow of data between computers, as the name suggests. The Transmission Control Protocol, TCP and the User Datagram Protocol reside in this layer. In the transport layer, the data is segmented into parts to achieve a steady flow so that the differences in connection bandwidth between the host computers does not matter in the circulation of the data through the network.

Network layer
The Network Layer helps in transporting the data between the networks. At the beginning of the segments a network header is placed, which consists of the IP addresses of the sender and the receiver terminals. This header remains constant which is just read during the process of communication. The IP or Network trailer is also present at the end of the package, which contains the checksum to validate the data that is transferred between the networks. The Network Layer is employed by the routers to handle the network addresses.

Data link Layer
The data link layer takes input bits from layer one and arranges them into data structures called frames. It uses a frame header containing the sender and receiver addresses. These values do not remain constant and change while passing through the network nodes, routers or servers.

Physical Layer
The Physical Layer consists of the electrical part of the process of communication, the binary signals or bits that are transmitted and received in the process of exchange of data during the communication. The binary signal is a combination of 1's and 0's that may be repeated.

OSI Model

What is an OSI model?
      OSI stands for Open System Interconnect. It was developed by the International Organization for Standardization in 1974. The OSI model consists of seven layers with each layer having a different function of processing.
The seven layers of OSI Reference model are as follows:

OSI Model
OSI Model

What is web hosting? Find out here.

The Open System Interconnection model defines implementations for networking framework protocols in seven layers. Starting from the application layer in one station, the control is circulated from one layer to the other over the channel to the next station and back up the hierarchy.

Application layer

The application layer is the seventh or topmost layer of the OSI Model. The Application Layer is responsible for providing end-user services, such as file transfers, electronic messaging, e-mail, virtual terminal access, and network management. This is the layer with which the user interacts with the application. This interface may be command-line-based or GUI-based. Cisco routers and switches have a command-line interface, while a web browser uses a graphical interface.The application layer refers to applications that are network-aware. There are thousands of computer applications, but not all of these can transmit information across a network Examples of application layer programs are telnet, FTP, web browsers, and e-mail.

Presentation layer
The Presentation Layer establishes context between Application Layer entities, in which the higher-layer entities may use different syntax and semantics if the presentation service provides a mapping between them. If a mapping is available, presentation service data units are encapsulated into session protocol data units, and passed down the stack.

Session layer
 The session layer is the fifth layer of the OSI model that controls the connections between computers. Its responsibility is to establish, manage and terminate the connections between the client and remote applications. Session layer provides full duples, half duplex and simplex operaions of communication.

Phases of web hosting

There are four main phases or sequences of hosting a website, which are discussed below:

  • Simple internet presence
           This is the most common and most basic type of website that is simplest to set up and least expensive as well. This type of website is a medium of direct communication of an website owner to the clients. It contains general information about the business firm, its objectives, missions, news, press releases, products and views, services, contact information etc. It may contain annual reports and specialized news bulletins, as well as a dedicated area for visitor feedback.

  • Basic E-commerce or E-business website

This category of website is somewhat complex version of the simple internet presence website, complex to mean that it consists of much more information compared to the simple internet presence websites. It consists of a number of substantial enrichment features that provide extra functionality to the website. The extra features may consist of an online store of various goods and services with secure ordering capabilities, integrated online call centers, FAQs and fact sheets, etc.

 Advanced E-commerce or E-business website 
                   Advanced websites consist of increased functionality such as web based software and core applications to dynamic IP based systems and applications. Off-the-shelf and custom software applications can be integrated with enterprise websites to enhance various processes in a number of areas such as automated processes, general business applications, data management functions and automated software, private IP-based networks, etc.

    • Fully Integrated E-business web presence
               At this fourth stage of development, the firm or enterprise has become a fully integrated E-business with intranets, extra-nets and discrete enterprise system working together. The back-office and front-office functions work together as an integrated system for the ease of ordering, asset and inventories management, and knowledge management throughout the system. In this model, the institution has become a true E-business.