Internet Layer: IP

Aka Internet Protocol address

IPv4

• An address consists 32 bits (8 bits x 4 octets)
• A 8-bit octet can represent a decimal value from 0 to 255 (2^8 = 256 values)
• Total Addresses: 256^4 = 4,294,967,296 ~= 4.3 billion

IPv6

• An address consists 128 bits (16 bits x 8 blocks)
• A 16-bit block can represent
  • a hexadecimal value from 0000 to FFFF
  • a decimal value from 0 to 65535 (2^16 = 65535 values)
    • F in hexadecimal is 15 in decimal
    • FFFF is (15 * 16^3) + (15 * 16^2) + (15 * 16^1) + (15 * 16^0) = 65535 in decimal
• Total Addresses: 65535^8 = (2^16)^8 = 2^128 ~= 340 undecillion

Transport Layer: UDP

Aka User Datagram Protocol

• No Handshakes (cheap, low latency)
• No resent mechanism (Not reliable)
• Application Layer using UDP
  • WebRTC (Streaming, it uses both TCP and UDP)
  • VoIP (Audio Streaming, Voice over IP)
  • DNS
  • DHCP (Router)
  • NTP (Clock, Network Time Protocol)

Transport Layer: TCP

Aka Transmission Control Protocol

• 3-Way Handshake (expensive, high latency)
• 2-Way Connection (Both side can Send and Receive)
• It has resent mechanism