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Is the OSI Model Still Relevant?

For decades the OSI Model has been the standard framework to understand how data flows. Will it survive as new internet models emerge? 

 By Michael Sumastre
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Perhaps one of the bones of contention in the halls of IT is whether the OSI model is dead. Some pundits believe that what is universally known may not die at all; instead, they evolve. On the other hand, a number claim that the internet models are more suitable in this day and age.  

But to know where the answer lies is to understand what the OSI model is. How does it work, and why has it become popular through the years? 

What Is the OSI Model?

Also known as the open systems interconnection, it is a conceptual or visual model of how networking systems communicate. Most IT experts think about it as a vertical structure composed of seven layers, stacked one after the other. 

The 7 layers of the OSI model include:

  • Physical layer (layer 1) – This refers to the physical manner in which networks connect. Think of cables, wires, and bitstreams. 
  • Datalink layer (layer 2) – This features two sublayers called media access control (MAC) and logical link control (LLC). This is similar to the first layer, except that it involves data transfer between two devices within the same network. In other words, the communication is node to node. It also corrects errors that may occur in the physical layer.
  • Network layer (layer 3) – One of the most popular components under the network layer is the router. The purpose of this layer is to determine the most efficient route for data to take. This information may still come from the servers located miles away.
  • Transport layer (layer 4) – The transport layers coordinate the transfer of data from hosts to end systems or users. These include the rate of data transfer, the path taken, etc. Here, one of the well-known internet models called TCP/IP is involved. While IP contains information about the data, TCP is the protocol that facilitates the movements of messages between computing devices.
  • Session layer (layer 5) – In the OSI model, the session layer controls the opening or closing of a session, which is the communication between two devices. The best example of this is the transfer of files from one PC to another. Another use of the session layer is to efficiently use the available network resources. 
  • Presentation layer (layer 6) – The presentation layer focuses on at least three vital processes that make data more presentable and understandable by an application. These are compression, encryption, and translation.
  • Application layer (layer 7) – Of all the OSI model layers, this is the layer that most end users often interact with. The application or software itself doesn’t form part of the application layer, but instead, they are managed by layer 7. It helps present more meaningful data. Think of it as the protocol that processes content requests and displays content in an ideal format. 

Also read: New Momentum for IPv6 Deployment

Why Do IT Pros Like the OSI Network Model?

It was in the 1960s when companies began using computers, such as mainframes. As IT evolved and allowed various computing devices to communicate with each other, even when they’re not in the same area, the OSI model became the standard framework to understand how data flows. Because of this, many IT operators prefer the OSI model for the following reasons:

  1. When they need to troubleshoot, they don’t have to go through all layers of the network. For instance, if a PC loses an internet connection, they can begin their inspection in layer 1 to check that all cables are properly attached. They may then proceed to layer 3 to see if the networking components like routers are receiving information properly.
  2. The OSI model may help mitigate cybersecurity risks. The issue of cybersecurity remains the biggest concern among enterprises, particularly to small businesses. One hit may lead to bankruptcy and shutdown of the company within 6 months.
    With OSI, a DDoS attack may hit any layer; but with prompt monitoring and implementation of security measures including zero trust, an IT administrator can quickly isolate the problem before it spreads to the other layers. On the other hand, an attack on an app usually limits it only to the application layer. This way, it’s easier to isolate and resolve. 
  3. IT operators also like the fact that they can specialize. For example, if they want to design apps, they can focus solely on learning more about the application layer.

Also read: Understanding the Zero Trust Approach to Network Security

If It’s Vital, Why Do Others Consider the OSI Model Obsolete?

In 2019, the 451 Alliance, a group of networking and IT professionals, published an article saying that the OSI network model is dead. According to them, the OSI model may not work in this day and age of IT because:

  1. The “internet models” are here, and it’s vastly different from the OSI model. Unlike the latter, the internet models only have four layers. These include network access, internet, transport, and application. They are less rigid, so they are more flexible and easier to adjust to meet the networking needs or demands of a business. 
  2. The internet models seem to be more focused on the integration of various components and applications. As stressed by the 451 Alliance article, companies need not buy a full stack of platforms from one or a few vendors. Instead, they can source out what they need from various sellers and companies. In turn, they can choose platforms that are not only cost-effective but also efficient.  
  3. The “bureaucracy” that exists in the OSI network model may be its downfall. The 7 layers of the OSI model are highly dependent on one another. If the lower layers fail, then there’s a good chance the higher ones will also not work. The internet models, such as TCP/IP, provide a more flexible architecture

What is OSI's Future?

With these changes, what’s the future of the OSI model? Perhaps the answer is simple: like everything else, it will also go through massive evolution. The original idea of the OSI model may no longer exist within the next few years. However, the core of it, which is how it defines data transmission within a network, may still help thousands of IT experts develop tech that makes their systems more efficient and reliable.

Read next: Taking the Unified Threat Management Approach to Network Security

This article was originally published on Mar 5, 2021
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