The Internet

Networks, IP, TCP

An overview of IP and TCP

Local Area Network (LAN)

Connect a small group of devices

Internet Service Provider (ISP)

Connect customers to The Internet

Tier 1 Networks

Tier 1 networks form the backbone of the Internet

Data Centers Power Apps

It's all Cables!

How do we use these cables?..

Internet Protocol

Internet Protocol (IP) Address

• Every device has an IP Address
  • Use this address to send messages to that device
  • Ex: 172.217.12.211
• Use DNS (Domain Name Server) to lookup IP address by domain name

Data is sent over the Internet in packets/datagrams

• Each packet contains headers containing information about the packet

• Large messages are sent in multiple packets

Routing Packets

• To route a packet through the Internet, a router will
  1. Check the destination IP address of the packet
  2. Send the packet to the next router on its path
  3. Fuhgettaboutit

The Internet is Unreliable

Many factors cause packets to be dropped

Transmission Control Protocol

Transmission Control Protocol (TCP)

• Makes the Internet reliable
• Detect and resend dropped packets
• Adds port numbers to identify specific programs
• Connect to a port number/IP address combination (TCP/IP)
  • 127.0.0.1:8080

TCP/IP in CSE312

• Use libraries to do all this for us
• Assume TCP/IP works and that we have reliable communication over the Internet
• Freely send and receive messages (As bytes)
• Your code (HW) will start with HTTP
• Much deeper TCP/IP coverage, and more, in CSE489: Modern Networking Concepts

Further Reading

• IP (Wikipedia)
• TCP (Wikipedia)