What Is and How the Internet Works
Tags: webdev, computerscience, network, discuss
Published: 2021-04-02 15:20:42

Hi Devs! If you are a developer before putting our hands-on code it's better to know how the Internet works and if you are experienced you can brush up on the concepts.

Without delay let's Dive in

# Different Views of Internet

- ***The Internet: Nuts And Bolts view***
    - Computer Network → (Example: Connection between two computers through LAN cable)
    - Internet → Network of Networks

![Internet - nuts and bolts view](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/zdk5mrimhwo49owqeotu.png)  


- In Packet Switches
 circle → Routers
 square → Switch
 Router → Connects *devices across multiple networks* . Finds the shortest path for a packet. *Network* Layer
 Switch → Connects *various devices in a network* . *Data Link Layer*.
Modem → Connects *various devices such as PC, Desktop to the Internet.* *Data Link Layer*.

    - Difference between Routers & Switch
![Alt Text](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/z3r6zhz0gvr1omdomhwz.png)
    - Difference between Routers & Modem
![Alt Text](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/qlk83d8u0oapbsiat0vc.png)

- ***The Internet: Services view***

    ![Internet - services view](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/bh2n4szjhmouh7oo3zqc.png)


    - Example for Using the Internet as a Service in applications
        - Streaming Video from Datacenter (content Provider network) to mobile network
        - Using HTTP protocol from Datacenter (content Provider network) to enterprise network
        - Skype calls between mobiles use the Internet
- ***Internet Structure***
    - **Network edge** → Clients & Servers

        Clients → end-user requesting www.google.com

        Server → serving [www.google.com](http://google.com) page  (often in data centers)

    - **Access network & Physical Media →** wired, wireless communication links

        The connection between our mobile, laptop to the routers(end host to Router(ISP))

        - To connect end systems to edge router(router at the edge of our network)
            - Residential access nets

                Access Networks: Home Networks

                ![Alt Text](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/ie8lvsoq83nefu8q3ng8.png)

                Wireless Access Networks

                ![Alt Text](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/2cbm2oisehrk60ftwhel.png)

            - Institutional access network(school, company)

                ![Alt Text](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/g911w8pbrzzairt1wqi9.png)
            - Mobile access networks(WiFi, 4G/5G)
    - **Network core → mesh of interconnected routers**, ISP's, network of networks
        - Connection between multiple routers
        - Packet-switching ⇒ Hosts break the application layer messages into packets

            Network forwards packets from one router to next, across links on a path from source to destination(here algorithms are used to find the best path)

            ![Alt Text](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/a60xkc3tmnm8yrc3vtxe.png)

- ***Internet Flow when we hit [www.google.com](http://www.google.com) in our browser***

    Flow from our host to google data center (Content Provider) which is in the US

    > Host ⇒ Router ⇒ ISP ⇒ Network of Regional ISPs ⇒ Network of global ISP's ⇒ content Provider Datacenter

*Reference - Computer networking - A Top-Down Approach by Kurose Ross*