A Brief History of Non-Routable Address Space

🕰️ The Dawn of IPv4: A Growing Internet

Even in 1996, it was clear that the internet's growth was unsustainable. The original IPv4 standard defined an IP address as a single 32-bit number, capable of representing 4,294,967,295 unique addresses. While this seemed like a vast number, by 2017, the estimated human population on Earth had reached 7.5 billion. This meant that IPv4 didn't even have enough addresses for every person on the planet, let alone the countless devices and data centers required for modern technology.

💡 RFC 1918: Defining Non-Routable Address Space

In 1996, RFC 1918 was published to address this growing concern. RFC stands for "Request for Comments" and is a long-standing mechanism for internet stakeholders to agree on standard requirements. RFC 1918 outlined a number of networks that would be defined as non-routable address space.

🔒 Understanding Non-Routable Address Space

Non-routable address space is exactly what it sounds like: ranges of IPs set aside for use by anyone that cannot be routed to. This means that computers within these networks can communicate with each other, but no gateway router will attempt to forward traffic to them.

🌐 NAT: A Bridge to the Internet

While non-routable address space might seem limiting, a future module will cover Network Address Translation (NAT), a technology that allows computers on these networks to communicate with other devices on the internet.

🏘️ The Three Primary Ranges of Non-Routable Address Space

RFC 1918 defined three ranges of IP addresses that will never be routed by core routers:

• 10.0.0.0/8

• 172.16.0.0/12

• 192.168.0.0/16

These ranges are free for anyone to use for their internal networks. It's important to note that interior gateway protocols will route these address spaces within an autonomous system, but exterior gateway protocols will not.

🎉 Congratulations!

We've covered a lot of ground in this module. Congratulations on sticking with it!