Networking Protocols - TCP/IP and OSI Models

Today I'm going to cover Protocols and Standards within Computer Networking, more specifically, the TCP/IP and OSI conceptual models for communication. We're going to look at how they link together to form the framework for device-to-device communication over local and worldwide networks. 

There are a plethora of different types of Standards and Protocols in Computer Networking developed and worked upon by a variety of agencies. All with the striving goal of creating seamless, instantaneous communication. They are required, to govern systems and to ensure structure and reliability in the products available and the functions across multiple communicable platforms. In short, the conceptual model remains relevant whether a device, is running the latest Apple Operating System, Windows or Linux.

Network communications protocols can be split down into seven different layers using the OSI model. The OSI model was developed in 1984 by the International Organisation for standardisation (ISO) and remains continues to be the structure on which Network Protocols are based. 'OSI' is the abbreviation for 'Open Systems Interconnection Model'.

There are seven layers that make up the OSI model, and they can be remembered in a variety of different mnemonic phrases. for example;

• All People Seem to Need Data Processing

• Please Do Not Throw Sausage Pizza Away

Each layer actually provides a strict set of protocols and are represented below in corresponding order:

• Physical (Layer 1)
• Data Link (Layer 2)
• Network Layer (Layer 3)
• Transport Layer (Layer 4)
• Session Layer (Layer 5)
• Presentation Layer (Layer 6)
• Application Layer (Layer 7)

 The Physical Layer transfers data at the binary level. This means all data is translated into ones and zeroes before it is transferred along a network medium. Layer one also governs network media and signals; this includes network cabling and wireless transmissions of devices connected to the network.
At Layer 2 or the Data Link layer, bits are encoded/decoded and appropriate IP addressing information is added before the data frame can be sent across the network. If this wasn't done, the data wouldn't know its destination and would never arrive.
The Network Layer follows on from the Data Link Layer, and works on four basic principles to complete its job. It addresses and encapsulates the data before it is routed across the network, once it arrives at its destination, the packet is then de-encapsulated.
The Transport Layer opens up temporary communication between applications on a network, allowing the transference of data between the two applications.
The Session Layer opens up and controls the communication between several computers. Whilst it is active, it maintains and controls the temporary connections between multiple devices.
The Presentation Layer formulates the information that has been transferred over the network back into a readable/understandable format for the end-user.
The Application Layer is the system that provides the interface for the end-user to use. Application Layer protocols are used to exchange data between programs running on source and destination systems.

There is an equivalent set of standards to the OSI model and that comes in the form of the TCP/IP model.
TCP stands for Transmission Control Protocol, and it is a standard that defines how to create and maintain network communications. This includes everything from establishing communication with other devices, either on the same network or across vast distances. It also ensures all data is transmitted as quickly and efficiently as possible, with minimal to no errors.
The IP part of TCP/IP naturally stands for Internet Protocol. Internet Protocol can be viewed similar to that of a postal code, wherein without it, you wouldn't be able to send letters or packages. To put that in computing terms, you wouldn't be able to send and receive files or videos.
The TCP/IP model is broken down into four layers as opposed to the OSI model's seven layers.
Again, just like the OSI model, there is a mnemonic which can help you to remember the order of the Layers, and it is as follows. The best way to remember the TCP/IP model is with this sentence: 'TCP/IP comes in A TIN'

• Application
• Transport
• Internet Layer
• Network Access

The Application Layer represents and controls the functions of the Application, Presentation and Session Layers.
The Transport Layer represents its counterpart in the OSI model.
The Internet Layer represents the Network Layer, and the Network Access layer controls the combined functions of the Data Link and Physical Layers.

Thank you for reading the latest rambling of my blog. As always, if there is anything that you would like me to cover, either new topic or something in more depth, please let me know. Also, if I've made any mistakes in the writing of this topic, please inform me so I can make the necessary amendments.

Until Next Time!