OSI Model: What is it, what is it for and what is its importance in computer network protocols?

Network protocols are different from each other depending on the characteristics assigned by their developer or manufacturer. The question would be how do those programmers manage to design a network that can connect and exchange data blocks with others? The answer is easy: “because they comply with the OSI layer model”.

In this article we will explain how the standards established by the International Organization for Standardization (ISO) they ensure greater compatibility and improve operation between different types of network technology.

we will show you how information travels from programs to an applicationthrough a network medium, to other programs located on different computers on the network regardless of their geographical area.

What is the OSI layer model for computer network protocols?

The OSI model “Open System Interconnection”, are standards that were created for open systems. These universal standards or norms were launched by the International Organization for Standardization, ISO (in English “International Organization for Standardization”).

The model studies the protocols that open networks must comply with so that reliable interconnections can exist. between those networks, especially those that were created by different technological developers. That is, for a network to be identified by another, they must comply with the standardized parameters of the OSI layer model.

But before moving forward we will have to know some data that is necessary to be able to definitively understand what these standards for network protocols are about.

Source

Between the 60s and 70s networks with monolithic architecture began to have a very important growth, since companies realized the advantages offered by technology in managing their data.

This started to cause a major problem.the technologies of the different companies could not communicate with each other, since their protocols with which they were developed were not the same, generating incompatibility between them.

Many companies solved this problem designing a third network that it could read the protocols of both original networks, but it also did not solve the problem definitively because that network was also incompatible with other open networks from other manufacturers.

These problems became bigger and bigger and many companies began to pressure the US government to start taking action on the matter.

History

It was only in 1984 when the OSI model definitively emerged.which had its acceptance in the ISO standards with the number ISO/IEC 7498-1which attributes 7 levels to be able to comply with the OSI model.

It establishes the rules or universal language that all network protocols must have. so that it can be considered as such, thus guaranteeing affinity with other networks.

Evolution

After the acceptance time of the OSI model, more flexible protocols began to existas the model itself does not hold so exactly in reality and the layers are not as different as the model indicates.

Although it is a model that works perfectly for teaching networksit is also one that manufacturers are most inclined to when developing their network protocols, without being entirely exact as indicated by its model.

What are the advantages of devising a computer network with the ISO model?

Among the advantages proposed by devising a computer network with the ISO model, we can name the following:

• The OSI reference model can be used to establish a framework that can make it easier to understand how information travels on a network.
• It allows to visualize how the data packets or Blockchain travel from the application programs through a specific network medium and reaches another program, located on another computer also on the same network, even when the one that sends and the one that receives that information have different types of network media.
• It allows to divide the existing communication in the network into simpler parts And small.
• Standardize different hardware and software of a network so that they can communicate with each other.
• They standardize the components that a network has allowing the development and support of the different products offered by manufacturers.

What are the layers of the model and what is their function within the network?

As we told you before, the OSI model establishes standards for universal communication between different network protocols, analyzing how data blocks travel through the network, helping to understand the action that occurs between communication from one computer to another.

To do this, the model has divided the work into 7 different levels or layers, each of which has a specific mission.

We will show you each of them from the highest to the lowest:

App

The application layer is the closest to the usercharacteristics that do not provide services to any other layer of the OSI model, but only serve to provide network services to the applications that the user has.

An example of this would be an Excel spreadsheet or Internet browsers.

Presentation

It is the layer that is dedicated to the representation of data.that is, it guarantees that the information issued by layer number 7, that is, the application layer, is read.

This layer is dedicated to translating between various established formats the data used in a common format so that it can be understood by the receiver allowing the data to be compressed and encrypted.

Session

When two hosts are communicatingthis layer is the one dedicated to establishing, managing and ending the session between them. The layer aims to offer different arrangements for efficient data transfer and service classes.

Transportation

The Transport layer is dedicated to end-to-end connections., that is, it transports the data trying to isolate the upper layers of the implementation details. This layer properly establishes, contains, and terminates all virtual circuits providing reliable service.

Net

The so-called network layer is that it provides the connectivity and selects the path between two host systems.regardless of whether they are located on geographically different networks.

In this layer is where the routers are located, whose mission is to route the functions, fragment the data and later reassemble them.

This layer is divided into three parts:

• Access
• Convergence
• Convergence Independent

data link

The OSI Data Link model layer, Its function is to provide reliable transit through physical links.. That is, it deals with the physical addressing, the access that the network may have, its topology and flow control.

It is divided in turn into:

• sublayer of logical link control (LLC)defines how the data blocks will be transmitted.
• sublayer of medium access control (MAC)its mission is to act as controller of the network adapter, that is, the underlying hardware.

Physical

The first layer defines all those technical specifications, whether mechanical, electrical, functional, to activate or deactivate a physical link between end systemsAmong other functions.

It is also dedicated to everything related to voltage, voltage timing changes, physical data speed, physical connectors and any other attribute that is defined as a physical specification.

List of the main protocols that work between the 7 layers of the OSI model

There are different protocols that work as a set of rules and procedures between two or more computers that belong to a network, and since we are dealing with the analysis of the OSI model, we want to show you the most important ones that you can find in said model.

Next, we detail them:

IP

Of English “Internet protocols”, data is sent over the network through blocks that we call packets or datagrams and differ in size. belongs to the layer “Net” of the OSI model.

This protocol does not guarantee whether or not a datagram reaches its destination correctly, since they can arrive duplicated, broken, or in a different order than they left, or they simply do not arrive.

TCP

The transmission control protocol named for “Transmission Control Protocol”it is one of the most used protocols on the Internet.

It is responsible for managing the flow of data that comes from the lower layer of the OSI model or goes to that layer. Its mission is that two computers that are connected to the network can control the transmission of data.

This protocol belongs to the layer “Transportation” of the OSI model.

NetBIOS

The network protocol created to provide services such as:

• name servicewhich records the names of computers, applications, and any other identifiable devices connected to the network.
• package servicesfacilitates the sending and receiving of data packets from a network.
• session serviceis similar to the TCP protocol, this allows to generate the establishment of connections between two or more points that belong to a network.

The NetBIOS protocol belongs to the layer “Session” of the model.

Wifi

Wireless Fidelity is a set of standards for wireless networks which are based on IEEE 802.11 specifications. It is also used for Internet access.

This protocol belongs to the stage “data link”.

HTTP

This protocol used for Internet access belongs to the “App” of the OSI model. They are logical links which are responsible for processing and responding to all the requests we make to view a web page.