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The IPv4 stock is running out

Since April, ARIN, the American Registry for Internet Numbers is digging through their last IPv4 addresses, with fewer than 17 millions IP addresses left. The same point that has been reached by the APNIC (Asia-Pacific) three years ago already, and the RIPE NCC, in Europe, less than two years ago. All the registries – except AfriNIC – are restricting the distribution of IPv4 addresses blocks.

For some years now, we have been multiplying the number of devices accessing the internet. The use of ADSL and the “always-on” internet, the multiplication of computers and other devices at home, and the ever growing number of connected devices were many steps that led to the current situation: we need more and more IPv4 addresses. Unfortunately, we don’t have an infinite number of addresses to give, and the stock is running out.

In its first version, the IPv4 addressing was split into classes: classes were subdivisions of the whole IP space – 5 in total, and the class an IP belonged to determined the number of networks and the number of computers. The system worked well as long as there were not too many computers. But soon, we noticed that the system was far from perfect: we needed more IPs, and the class subdividing made no sense with too many big blocks to be able to share addresses efficiently. So, just before it became a real problem, we set up classless routing, suppressing the classes and allowing to create smaller IP blocks, already trying to solve the problem of the limited number of IPs.


We already set up a solution to brake the consumption of IP addresses: NAT. NAT allows multiple computers to be on a “private” network, all sharing the same public address. This way, a single home will have one IP address, whatever the number of devices are connected. Unfortunately, even if it slowed down the phenomenon, it didn’t stop it. So ISPs are thinking of deploying CGNs, a NAT at the ISP level, grouping multiple houses in a “private” network. This way, your devices may be behind multiple layers of NATs. If this solution solves the problem of addressing, it also creates technical difficulties for the access of services. In fact, NATs are no problem when you connect to the external world, but it make it difficult to get connections from the external world, and each layer makes it even harder. Massive deployment of CGNs may break many applications. Actually, deployment of CGN already began.

The other solution to the exhaustion of IPv4 addresses is called IPv6. IPv6 is a new way of addressing devices based on a longer address. The 128-bit long address will push the limit away, maybe forever, even when giving each device a public IP. This will also remove the need for NAT, making easy again to connect to the internet, whenever the connection goes in and out.

The current problem with IPv6 is that some ISPs are slow to deploy it. Some of them don’t want to deploy it yet. Devices are IPv6-aware for a long time now, but the network is not adapting yet. Nowadays more and more devices are using IPv6 already, but it’s not currently enough. But the internet need it now, as it currently gets to its limits.

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