{"id":1774,"date":"2020-11-16T09:58:00","date_gmt":"2020-11-16T09:58:00","guid":{"rendered":"https:\/\/sectigostore.com\/blog\/?p=1774"},"modified":"2020-11-13T23:59:39","modified_gmt":"2020-11-13T23:59:39","slug":"how-osi-model-network-communication-layers-work","status":"publish","type":"post","link":"https:\/\/sectigostore.com\/blog\/how-osi-model-network-communication-layers-work\/","title":{"rendered":"How the OSI Model & Network Communication Layers Work"},"content":{"rendered":"\n

The internet isn\u2019t an abstract idea but has real physical existence. Let\u2019s explore how computers and other devices communicate via networks\u2026<\/strong><\/h2>\n\n\n\n

Not so long ago, sending messages to someone living on a different continent required significantly more effort than rolling out of bed and hitting send on your email client. Today, it\u2019s possible to communicate almost instantaneously with our coworkers and buddies. But how exactly does data travel from your colleague\u2019s laptop or your friend\u2019s phone to your device? This is where the OSI model comes into play.<\/p>\n\n\n\n

The OSI model and network communications are all about the layers.<\/p>\n\n\n\n

What Is the OSI Model?<\/h2>\n\n\n\n

The Open Systems Interconnection Model<\/a> (or OSI model) is a framework given to us by the International Organization for Standardization (ISO). Its purpose? To standardize communication protocols and agree on network standards for multi-vendor interoperability. In other words, it enables various devices manufactured by different vendors to communicate in a uniform way. It also serves as a way for people to break down different parts of network systems based on their functions for network communications.<\/p>\n\n\n\n

Network Layers: OSI Model vs TCP\/IP<\/h3>\n\n\n\n

Besides the OSI model, the TCP\/IP reference model with its four layers is also used as an industry standard. Now, you may be wondering, isn\u2019t the OSI model the same thing as the TCP\/IP model? Yes and no. They\u2019re related but still separate.<\/p>\n\n\n\n

TCP\/IP, which stands for transmission control protocol\/internet protocol, is a protocol suite that traditionally consists of four layers \u2014 application, transport, internet, and link. Layers 5, 6, and 7 of the OSI model are mapped to the TCP\/IP model’s application layer. The OSI network layer is referred to as the internet layer in the TCP\/IP model. Layer 4 of the OSI model is mapped to the corresponding transport layer, while layers 1 and 2 are clubbed into the TCP\/IP model’s network access layer. This suite was created almost a decade before the OSI model came into existence.<\/p>\n\n\n\n

Dummies.com<\/a> really clarifies the difference between the two nicely:<\/p>\n\n\n\n

\u201cThe OSI Model isn\u2019t itself a networking standard in the same sense that Ethernet and TCP\/IP are. Rather, the OSI Model is a framework into which the various networking standards can fit. The OSI Model specifies what aspects of a network\u2019s operation can be addressed by various network standards. So, in a sense, the OSI Model is sort of a standard\u2019s standard.\u201d<\/em><\/p><\/blockquote>\n\n\n\n

Familiarizing yourself with the OSI model network layers helps you understand how telecommunication systems work in a granular sense. This can help you identify or resolve issues facing your network. It also helps you see the bigger picture of how data flows between interconnected devices over a network.<\/p>\n\n\n\n

\"osi
A visual breakdown of the four- and five-layer TCP\/IP models in relation to the OSI model layers.<\/figcaption><\/figure>\n\n\n\n

Breaking Down Network Layers: A Look at the 7 OSI Model Layers<\/strong><\/h2>\n\n\n\n

The OSI model is more of an interoperability guideline for manufacturers and developers than a strict representation of how the network looks. Instead, it gives an overview of how the data flows across the network. There are seven layers in this model, each with its own set of functionalities and protocol suite. The layers are typically listed in descending order \u2014 starting with layer seven and making their way down to layer one.<\/p>\n\n\n\n

Let\u2019s consider how this would work in a two-party connection \u2014 say, between your computer and a friend\u2019s computer. The seven layers exist on both host devices, and each layer exchanges data with its corresponding counterpart independently of the other layers below. This means that if you send data from your computer to your friend, data on your device\u2019s OSI layer 2 would exchange directly with your friend\u2019s layer 2. Your layer 3 would exchange data with their layer 3, etc.<\/p>\n\n\n\n

However, there\u2019s one key bit of info we need to touch on. As the data travels down from the application layer of your computer, additional information gets added to the data before it is passed on to the layers below. This process is called data encapsulation<\/strong> because it involves adding protocol information to the beginning (header) and\/or end (trailer) of the data. <\/p>\n\n\n\n

At the recipient\u2019s end, data decapsulation takes place where the incoming data is unpacked as it moves up the layer till finally, at the application layer, all the additional headers and\/or trailers added are stripped off.\u00a0<\/p>\n\n\n\n

\"a
The OSI Model Layers: Data Encapsulation & Decapsulation<\/figcaption><\/figure>\n\n\n\n

Since data moves from the top down when leaving the sender to transmit to the recipient, it seems fitting that we start with seventh layer of the OSI model and work our way down. Let\u2019s explore the OSI model layers!<\/p>\n\n\n\n

OSI Layer 7: Application Layer<\/strong><\/h3>\n\n\n\n

The seventh layer of the OSI model is called the application layer. As the name suggests, it deals with software and applications that run on our computers, such as the web browser you\u2019re using to read this web page. Basically, this layer interacts with end-users through those apps and provides an interface between them and the underlying network connections. Some of the primary protocols used at the application layer are HTTP, DNS, FTP, SMTP, etc.<\/p>\n\n\n\n

The application layer forms the human-computer interaction interface that focuses on end-user services. We rely on the application layer whenever we:<\/p>\n\n\n\n