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Network Protocols

Dec 24, 2024, 2 min read

Network Protocols

A protocol is an agreed-upon set of rules for communication. Clients and servers communicate via various existing protocols.

IP (Internet Protocol)

  • Yes, this is what the IP in IP Address stands for
  • Data sent from one machine to another is sent via IP packets at it’s most basic level
  • These packets contain a header & data:
HeaderPayload
Source IP
destination IP
size of packet
IP version - IPv4 or IPv6		Arbitrary data

(Ignore the scaling of the diagram - in reality, the payload is much larger)

  • These packets are bytes maximum - this isn’t a lot of data! Therefore a great many packets have to be sent across the wire
  • IP does not guarantee ordering
  • IP has no way of confirming that the recipient received anything
  • No error correction

TCP (Transmission Control Protocol)

  • To address the shortcomings of IP, TCP was created
  • This has a way to see if data was received and guarantees the correct ordering
  • Allows you to send arbitrarily long pieces of data
HeaderTCP HeaderPayload
Source IP
destination IP
size of packet
IP version - IPv4 or IPv6		Info about payload
Ordering data		Arbitrary data
  • For a client and a server to communicate, a TCP connection is made and this connection is held open until a timeout or the client or server requests to end the connection
  • This connection is opened via a handshake

HTTP (HyperText Transfer Protocol)

Requests

  • host -> adambennett.dev
  • port -> typically 80 or 443
  • path -> /posts
  • method -> GET, POST, PUT, DELETE
  • headers -> content-type: application/json, content-length: 51
  • body -> arbitray data, typically JSON

Responses

  • status code -> 200, 404, 500 etc
  • headers -> content-type: application/json, access-control-allow-origin: 'https://adambennett.dev'
  • body -> arbitray data, typically JSON

For more, see REST API Design.

Summary

graph LR
	IP --> TCP
	TCP --> HTTP

Graph View

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