TCP IP Model

Detailed TCP/IP Layer Breakdown

Sending the Request (Client to Server)

1. Application Layer (Client Side): The client application (browser, API client, etc.) initiates the request for a service or resource.
2. Protocol Choice: The application decides the protocol (HTTP, HTTPS, FTP, etc.) and breaks the URL into components (protocol, host, port, etc.).
3. TLS Security: If using HTTPS, the data is encrypted using TLS.
4. Transport Layer (Client Side): The data is segmented using TCP or UDP, depending on the service.
5. Internet Layer (Client Side): IP headers are added for routing.
6. Link Layer (Client Side): The data is framed for local network transmission.

Client LAN Router to Internet

1. Client LAN Router: The router forwards the frame to the internet.
2. Router to Router Over the Internet: Data is routed through multiple internet routers.

Server Side Processing

1. Destination Network Router (Server Side): The data is forwarded to the server network.
2. Link Layer (Server Side): The data is framed again for the server network.
3. Internet Layer (Server Side): The data is processed for local network routing.
4. Transport Layer (Server Side): The data is reassembled, and TLS decryption occurs if necessary.
5. Application Layer (Server Side): The server processes the request and generates a response (headers and body).

Receiving the Response (Server to Client)

1. Application Layer (Server Side): The server generates a response (e.g., HTML, JSON) formatted for the client.
2. Transport Layer (Server Side): The data is segmented and encrypted with TLS (if applicable).
3. Internet Layer (Server Side): The data is routed towards the client.
4. Link Layer (Server Side): The data is framed for transmission across the server's local network.

Server to Client Routers

1. Router to Router Over the Internet: Data is routed back through the internet to the client.
2. Destination LAN Router (Client Side): The router forwards the data to the client device.

Client Side Processing

1. Link Layer (Client Side): The data is framed for local network transmission.
2. Internet Layer (Client Side): The data is processed and routed to the appropriate client application.
3. Transport Layer (Client Side): The data is reassembled, and TLS decryption occurs if necessary.
4. Application Layer (Client Side): The client application processes the data and presents it to the user.

Note: Higher protocols such as HTTP or FTP rely on lower protocols like TCP/UDP for transmission. TLS works primarily at the transport layer for security but may also interact at the application layer depending on the implementation.