IPv4 Limitations and RFC 1918

Overview

This lecture covers the limitations of IPv4 address space, the introduction of non-routable address spaces via RFC 1918, and their significance in network design.

IPv4 Address Limitations

• IPv4 uses a 32-bit address, allowing for 4,294,967,295 unique addresses.
• By 2017, the global human population exceeded available IPv4 addresses.
• Data centers and businesses require many more IP addresses than IPv4 alone can provide.

RFC 1918 and Non-Routable Address Space

• RFC 1918, published in 1996, established standards for private, non-routable IP address spaces.
• Non-routable address space refers to IP ranges that cannot be routed over the public internet.
• Devices using non-routable addresses can communicate locally but not directly with the wider internet.

Purpose and Use of Non-Routable Addresses

• Not every device needs to directly communicate with all others on the internet.
• Non-routable addresses are commonly used for internal networks and are not globally unique.
• Any organization can use these non-routable address ranges without risk of conflict on the internet.

The Three RFC 1918 Address Ranges

• The three main non-routable IPv4 ranges are:
  • 10.0.0.0/8
  • 172.16.0.0/12
  • 192.168.0.0/16

Future Topics

• Network Address Translation (NAT) allows devices in non-routable spaces to communicate with the internet (to be covered in a future module).

Key Terms & Definitions

• IPv4 — Internet Protocol version 4, uses 32-bit addresses for network identification.
• RFC (Request for Comments) — A formal document from the Internet Engineering Task Force defining internet standards.
• Non-Routable Address Space — IP address ranges that cannot be routed on the public internet.
• RFC 1918 — The standard defining private non-routable IPv4 address spaces.
• NAT (Network Address Translation) — A method for remapping IP addresses to allow private addresses to access the internet (future topic).

Action Items / Next Steps

• Review the three RFC 1918 non-routable IP address ranges.
• Prepare for upcoming module on Network Address Translation (NAT).