【Table of contents】

1. 1. Overview
2. 2. What is AWS?
3. 3. What is OSI reference model?
   • a) Different layers of OSI reference model
4. 4. Conclusion

• 1. Overview

  The OSI reference model, which is known as one of the basic knowledge in networking, is an important basic knowledge that you need to know when building various web services.
  You can run a web service without knowing the overview, but if you are looking for better form and efficiency, learning about the OSI reference model is one way to improve it.
  Especially when using AWS, knowing about the OSI reference model can lead to a more optimal use of the service.
  Check out the OSI reference model and AWS together to get more insight into the network.

• 2. What is AWS?

  AWS is a cloud computing service provided by Amazon.com, a leading online retailer.
  By using AWS, you can add various benefits to the web services provided by each company and add more environment to your content than ever before.
  A wide range of industries, not just specific businesses, can create better IT environments with AWS functions, which will be a tailwind for companies that want to develop full-scale IT businesses.
  If you want to start a new business or improve your existing business to fit the current Internet system, AWS is recommended.

  AWS is already being used by companies around the world and is the backbone of their business.
  For example, there are many benefits that can be obtained by using, such as safety that meets all security standards around the world, fault tolerance and high availability that supports continuation of services, and improvement of services that make use of rich developer and user information. Support is also available during the implementation process, so you can sign a contract while confirming the specific services that your company needs.

  Using AWS, businesses can enrich the following areas in particular.

  ・ Improve the system and development speed of web content.
  ・ Get backups of the critical data.
  ・ Construction of a robust system that can operate in the event of a disaster
  ・ Analysis of Big Data
  ・ Application to next-generation services such as IoT and AI

  The benefits of AWS are great, not only for businesses that mainly operate these services, but also for businesses that want to apply other services as their axis.
  Establishing an IT infrastructure for each business is essential to make your job run smoothly, so it's worthwhile to start using AWS now.

  In AWS, there are logically separated virtual networks called VPCs (Virtual Private Clouds), which make it possible to finely customize network settings.
  In order to utilize VPC, it is essential to have a basic knowledge of networking, so it is recommended that you have a basic knowledge.
  There are other services in AWS that may be easier to operate if you know the basics of networking, so take this opportunity to learn about the OSI reference model.

• 3. What is OSI reference model?

  The OSI reference model is a standard model defined by the International Organization for Standardization (ISO), which defines the functions of computers and other communication devices.
  The background is to provide an OSI reference model to make it easier to understand how the network works and to make communication standards common around the world.

  The goal was to provide uniformity in a network that could communicate in various ways, but as a result, the OSI reference model is no longer used and the basic rules, now called TCP/IP, help to build the network.
  Therefore, there are many people who do not know about the OSI reference model, and there is an opinion that it is not necessary to have it as knowledge in the first place.
  Knowing the OSI reference model, however, will help you understand the basics of networking and allow you to learn how it works in a smart way.

  Understanding the OSI reference model won't directly speed up the progress of your business or create a better work environment right away, but it may be an opportunity to improve it.
  The OSI reference model has a hierarchical representation that is easy to understand at a glance, making it easy to learn even for network beginners.

  • a) Different layers of OSI reference model

    The OSI reference model is characterized by dividing the points that a network should possess as features into seven levels.
    This table will help you understand what features you need in your network and what form it should take to build them.

    Layer	Name
    Layer 7	Application layer
    Layer 6	Presentation layer
    Layer 5	Session layer
    Layer 4	Transport layer
    Layer 3	Network layer
    Layer 2	Data link layer
    Layer 1	Physical layer

     

    Application layer
    It is layer 7 application layer that is closest to human behavior.
    It is characterized by its application-level processing functions, such as displaying search results from information put into the Web browser and sending them to an email address.
    The role of the seventh layer is to transform the results sought by humans so that they can be processed by the network.

    Presentation layer
    The presentation layer is the one that checks the character code, compression format, etc., and converts the data into a common form.
    For example, processing garbled text and mis-displayed images so that they don't become garbled is one of the tasks of the presentation layer, which is to convert them into a common form.
    Its role is to support and communicate with each other so that different computers can view the same content.

    Session layer
    It is the role of the fifth session layer to determine the start and end of the communication.
    It establishes sessions and supports logical connections between applications that use the system.

    Transport layer
    It is the fourth transport layer that ensures the reliability of the communication.
    Various controls are used to add information to the communication data and make the communication reliable.

    Network layer
    The role of the network layer is to enable data to be exchanged between networks with different communication partners.
    It identifies a network based on an IP address, called a logical address, and defines it by adding the information necessary for transmission.

    Data link layer
    The job of the data link layer is to determine which computers in the network to communicate with and to support the exchange of data.
    In the data link layer, the MAC address of the physical address is used to identify the destination of the data.

    Physical layer
    It is the first physical layer that specifies the physical specifications needed to send the data to the communication line.
    By determining physical factors such as connector shape, cable type, and communication speed, data can be exchanged between various models.

    Based on these hierarchies, the processed information is encapsulated in the hierarchy as a header, and eventually it is transmitted as an electrical signal.
    The receiver then does the reverse, removing the processed data in the process of transmission and decapsulating it into the original data.
    The OSI reference model defines the network as being based on this flow, so you can understand the basic structure of the net by understanding the overall picture.

• 4. Conclusion

  By understanding the OSI reference model, the network is much easier to understand. For example, it will be easier to understand which layer the AWS ELB (load balancer) corresponds to, and you will be able to make a better choice of services.
  Why don't you take this opportunity to understand the flow of communication and the role of hierarchy?