Understanding Internet Infrastructure and Protocols
Chapter 1: Internet Foundations
- Funding the Internet: Primarily by governments, agencies, and large organizations like NASA. The American government, for example, founded the Internet2 project.
- Regional Networks: Provide internet access within a specific geographic area, often formed by smaller networks connected together.
- Registrars: Private companies responsible for registering internet domains.
- InterNIC: A main registrar and information center responsible for maintaining domains.
- Internet Service Providers (ISPs): Companies that sell internet access to individuals and organizations (e.g., Batelco and Zain in Bahrain).
- Internet Society: A nonprofit private organization dedicated to the internet and its users, providing knowledge, policies, standards, and education.
Chapter 2: Network Communication
- How Networks Communicate:
- Application Layer: Converts message data into bits and identifies the sender and receiver.
- Presentation Layer: Translates the message into a language the receiver’s computer can understand (encoding).
- Session Layer: Establishes a connection and determines if data will be sent in half-duplex or full-duplex mode.
- Transport Layer: Protects data by checking for errors and breaking it into segments.
- Network Layer: Transforms segments into packets.
- Data Link Layer: Supervises transmission, confirms checking, and manages packet addresses.
- Physical Layer: The receiving point.
- How Networks Link to the Internet:
At home, you can connect to the internet through DSL provided by an ISP. To send data, you need a router, which acts like a traffic controller. The router determines the fastest path for each data packet based on the destination, sending packets to the next router, and so on. Routers also connect networks to each other.
Other methods include ISDN and DSL. Data can also be transferred via satellite.
Networks in a geographic area connect to form a regional network, and routers pass information between them. Regional networks are then connected to each other via high-speed backbones.
Chapter 3: TCP/IP Protocols
- How the Internet’s Basic TCP/IP Protocols Work: (Keywords: Breaking Data, Packets, Reassembling, Checksum, Sending End, Receiving End, Retransmit, IP Envelopes, Router, Route)
When data is sent over the internet, it is broken into small packets. A series of switches called routers sends each packet across the network. Upon arrival at the receiving computer, the packets are reassembled into their original unified form.
The Transmission Control Protocol (TCP) breaks the data into packets and recombines them on the receiving computer. It also performs a checksum to ensure data integrity.
The Internet Protocol (IP) routes the data across the internet using IP envelopes that contain information about the sender and receiver addresses.
A Router checks the IP envelopes, examines the addresses, and sends the packets along different paths based on internet traffic, forwarding them to the next router until they reach the endpoint.