Lecture Notes: Internet Protocols and Addressing

Introduction to Internet Connected Devices

• Estimated total number of devices connected to the internet: 20 billion
• Current challenge: IP version 4 (IPv4) supports only 4.29 billion addresses
• Network Address Translation (NAT) is used to manage limited IPv4 addresses

Limitations of IPv4

• IPv4 addresses are exhausted; no new IPv4 addresses available
• NAT helps connect multiple devices to the internet using few IPv4 addresses
• Some applications face complexities with NAT

Transition to IP Version 6 (IPv6)

• Solution: IPv6 with a larger address space
• IPv6 addresses are 128 bits long, compared to IPv4's 32 bits
• Visualization: Every grain of sand on earth could have 45 quintillion unique IPv6 addresses

Differences Between IPv4 and IPv6

• IPv4: Decimal numbers and periods (e.g., 192.168.1.1)
• IPv6: Hexadecimal values and colons (e.g., fe80::5d18:652:6ffd:8f52)
• IPv6 allows for both full-length and compressed address forms

Compressing IPv6 Addresses

• Rules for Compression:
  • Replace groups of zeros with a double colon (::)
  • Remove leading zeros in each group
• Example:
  • Full IPv6: 2600:dddd:1111:0000:0000:0000:0000:0001
  • Compressed IPv6: 2600:dddd:1111::1

Communication Challenges Between IPv4 and IPv6

• IPv4 and IPv6 are incompatible; cannot directly communicate
• Solutions:
  • Tunneling: IP traffic tunneled within the other protocol
  • Dual-stack configuration: Devices handle both IPv4 and IPv6
  • Translation: Converting between IPv4 and IPv6 addresses

Methods to Bridge IPv4 and IPv6 Networks

• 6to4 Tunneling:
  • Sends IPv6 over IPv4 networks
  • Limited by lack of NAT support
• 4in6 Tunneling:
  • Sends IPv4 over IPv6 networks
• Dual-Stack Routing:
  • Uses both IPv4 and IPv6 simultaneously
  • Allows applications to choose the appropriate version

Network Address Translation for IPv4 and IPv6

• NAT64: Translates between IPv4 and IPv6
• Requires a specialized NAT64 router
• DNS64: Special DNS server that translates DNS requests between IPv4 and IPv6

Example Process of NAT64

• IPv6 client communicates with an IPv4-only server
• DNS64 server facilitates DNS resolution
• NAT64 router performs translation between IPv4 and IPv6 addresses

Summary

• IPv6 is essential to address the limitations of IPv4 due to the increasing number of internet-connected devices
• Transition methods like dual-stack routing and NAT64 are crucial for current network interoperability
• Long-term goal: Move to a pure IPv6 environment for seamless communication

These notes cover the key points and technical details from the lecture on addressing the limitations of IPv4 and transitioning to IPv6, including methods to bridge the gap between the two protocols.