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The Internet “Nuts and Bolts view”

• The components of the Internet:
  • At the edge of the network are the devices which we use to connect to the Internet, these devices are often called Hosts or End Systems.
  • Then, there are devices that build the structure of a network which are Packet Switches which forward packets (chunks of data) between each others and between hosts and end devices → Packet switches are two types: Routers & Switches
  • Then, there are communication links that connects all the previous
  • Finally, All these are assembled into networks each network is owned by some entity.
• The presence of these multiple networks leads us to the definition of the internet which is the Internet is the network of networks. (Interconnected ISPs) → ISP: Internet Service Provider
• The sending and receiving of the data across the routers, switches and hosts is controlled by Protocols. (e.g., HTTP, streaming video, Skype, TCP, IP, Wi-Fi, 4G, Ethernet)
• Protocols typically defines a standard way of doing things and for the internet there are standards too, which are:
  • RFC: Request for Comments
  • IETF: Internet Engineering Task Force

The Internet “A Service View”

• As a service platform, the internet provides an interface that applications can use to send and receive information to each other
• So, the definition of the internet from a service point of view: the delivery of information from one point in a network to another
• Under the hood there are some distributed applications - provided through a programming interface- that:
  • contain “hooks” that allows sending an receiving data to connect
  • use internet transport devices
  • provides service options analogous(similar) to postal devices

What is a Protocol?

• Protocols define:
  • the format and order of messages sent and received among network entities
  • actions taken on message transmission and receipt
• All communication activity in Internet are governed by protocols

→ In the next sections, we are going to look more on the nuts and bolts point of view of the internet