IPv4 address shortage facts for kids

Internet Protocol version 4 (IPv4) uses a system of numbers to give every device connected to the internet a unique address. Think of it like a phone number for your computer or phone! There are about 4 billion IPv4 addresses. The problem is, there are now more than 4 billion devices that want to connect to the internet. This means we are running out of these unique IPv4 addresses.

How Are We Solving This?

The Future: IPv6

The best long-term solution is to switch to a newer system called Internet Protocol version 6 (IPv6). IPv6 has a huge number of addresses – trillions of trillions! This is enough to give every device in the world its own unique address, even far into the future.

However, moving to IPv6 isn't always easy. It's mostly different from IPv4, so internet companies (ISPs) and even homes sometimes need to update their equipment, like routers. Not all ISPs offer IPv6 yet. But there are special ways, like Protocol 41 and Teredo, that let an older IPv4 device connect to the newer IPv6 internet.

Sharing Addresses: NAT

Network Address Translation (NAT) is a way to share one public IPv4 address among many devices in a home or small office. Imagine a big apartment building that has one main street address, but each apartment inside has its own private number. NAT works similarly: your router uses one public IPv4 address to connect to the internet, but all your devices (like your phone, tablet, and computer) get private IPv4 addresses behind that router.

This is seen as a short-term fix because it usually makes it harder for other devices on the internet to start a connection directly to your devices without some special setup.

ISP Sharing: CGNAT

Carrier-grade Network Address Translation (CGN or CGNAT) is like NAT, but it's done by your Internet Service Provider (ISP). This means many customers of the ISP share just one public IPv4 address. It's another short-term solution to help ISPs connect more customers than they have public IPv4 addresses for.

Why CGNAT Can Be Tricky

The main problem with CGNAT is that it makes it very difficult or impossible for incoming connections to reach your devices. Because many customers share one public address, the ISP's system doesn't know which customer an incoming connection is meant for. This can cause issues if you want to:

• Host your own website or file server.
• Play certain online games that need direct connections.
• Use online security cameras or other smart home devices that need to be accessed from outside your home.
• Use file-sharing programs like BitTorrent.

Most home internet providers (land-line ISPs) don't use CGNAT yet, but many mobile internet providers do. Sometimes, ISPs that use CGNAT will offer you a dedicated public IPv4 address if you ask for one. They might offer it for free, for a one-time fee, or for a monthly charge. As IPv4 addresses become even scarcer, these public addresses might become more expensive or harder to get.

Images for kids

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  This chart shows how experts predicted IPv4 addresses would run out in different parts of the world.

See also

In Spanish: Agotamiento de las direcciones IPv4 para niños