The Open Systems Interconnection (OSI) Model - What is OSI Model?

Layers of OSI Model

a) "The OSI Reference Model has proven to be extremely useful in coordinating different groups working on the different parts of the problem." What problem is the author talking about and how was it solved?

The Open Systems Interconnection (OSI) model means a conceptual framework that shows the functions of a networking or telecommunication system.

Actually, it uses layers to help give a visual detailed description of what is going on with a particular networking system. This can help network managers narrow down problems. It a physical issue as well as computer programmers by when developing an application, which other layers does it need to work with. Tech vendors selling new products will refer to the OSI model that helps the customers to understand which layer their products work with or whether it works “across the stack”.

The purpose of the OSI model is to set of design standards for equipment manufacturers therefore they could communicate with each other. It defines a hierarchical architecture that logically partitions the functions needed to support system-to-system communication.
The layers interact with each other,by which each layer provides a service to the layer above it in the protocol specification. Each layer communicates few information with the same layer's software or hardware on other computers. When sending data, the higher layers expect the lower layers to help in order to deliver the data.

This model of layered functionality is also called a “protocol stack” or “protocol suite”. The nature of these stacks is that the lower layers do their work in hardware or firmware while the higher layers work in software.
The Open System Interconnection model is a seven-layer structure that specifies the requirements for communications of network elements


b) What are the elements of the OSI architecture?

The OSI reference model shows the standards for describing "Open Systems Interconnection" with the term 'open' chosen to focus the fact that by using these international standards, a system may be defined which is open to all other systems obeying the same standards throughout the world.

The OSI 7 Layers - 
  • Physical Layer
  • Data Link Layer
  • Network Layer
  • Transport Layer
  • Session Layer
  • Presentation Layer
  • Application Layer
Data transmission performance included as Bit Rate and Bit Synchronization. Modulation, switching, and interfacing with the physical transmission medium. Common protocols including Wi-Fi, Ethernet, and others
Hardware also including the networking devices, cables, modem, and intermediate devices such as repeaters and hubs.

c) Three types of construction of N connections on top of N-1 connections and two forms of error control are recognized by the OSI model, what are these? Explain briefly?

In the OSI model, the Transport Layer (Layer 4) performs the message segmentation, acknowledgement, traffic control, and session multiplexing. The transport layer also has the property in order to perform error detection and correction (resends), message reordering to ensuring the message sequence, and reliable message channel depending on the specific transport layer protocol used. The most common of the used transport layer protocols consists of both the Transport Control Protocol (TCP) and User Datagram Protocol (UDP).

d) What was the approach adopted by SC16?

The approach adopted by SC16 was to use a layered architecture in order to break up the problem into manageable pieces. The OS1 Reference Model is also a framework for coordinating the development of OS1 standards.
Storage Class Memory (SCM), the expanded capacity and low latency has the potential to transform the management of “Big Data” in the near future. In order to continue the commitment to SCM through the ongoing exploration of innovative new ways to support customers and ecosystem partners in the adoption of this ground-breaking technology.

e) "Layers have been chosen to break up the problem into reasonably sized smaller problems that
can be considered relatively independently". Explain briefly the seven layers.

In the OSI reference model, mainly talks about the communications between a computing system are split into seven abstraction layers:
  • Physical Layer
  • Data Link Layer
  • Network Layer
  • Transport Layer
  • Session Layer
  • Presentation Layer
  • Application Layer

Physical Layer:

It helps to define the electrical and physical specifications of the data connection.It establishes the relationship
between a device and a physical transmission medium. The physical layer is not concerned with protocols or other such higher-layer items.

Data Link Layer:

It corrects errors which can forms at the physical layer. It allows to define the protocol to establish and terminates a connection between two connected network devices.

Transport Layer:

The transport layer makes on the network layer to provided the data transport from a process on a source machine to a process on a destination machine. It is using single or multiple networks, and also maintaining the quality of service functions.

It shows how much data should be sent where and at what rate. It builds on the message which are received from the application layer. It may helps to ensure that data the units are delivered error-free and in sequence.

Network Layer:

It provides the functional and procedural means of transferring variable length data sequences from one node to another connected in different networks.

Message delivery at the network layer not give any guaranteed to be reliable network layer protocol.

Session Layer:

Session Layer that controls the dialogues between the computers. It may helps you to establish starting and terminating the connections between the local and remote application. Here it handles all the important log-on or password validation.

Presentation Layer:

Presentation layer allows you to describe the form in which the data is to exchange between the two communicating entities. It helps to handles the data compression and data encryption.

Application Layer:

Application layer interacts with an application program,is the highest level of OSI model. The application layer is the OSI layer, which is closest to the end-user. It allows users to interact with other software application. Example is an application such as file transfer, remote login, etc.

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