Credit Flickr user @mjb (Licensed under CC BY-NC-ND 2.0)

A proposal could free up “hundreds of millions” of internet addresses, buying a little more time in the move to IPv6. Seth Schoen (pictured) points to four types of address that are reserved for special purposes that may no longer be needed.

IPv4 uses 32-bit addresses, which allow for four billion possibilities. Just like counting views of Gangnam Style on YouTube, that once seemed an almost unimaginably large number that eventually proved insufficient.

Over the past few decades, that’s been one of the key reasons for switching to IPv6, which uses 128-bit addresses and allows for four quintillion addresses. While use of IPv6 is growing steadily, Google estimates that only a little over a third of connections it receives use the protocol.

Schoen, formerly of the Electronic Frontier Foundation, thinks it might be useful to find some extra room for IPv4 addresses for now. He says the key could be blocks of addresses that were reserved for special use cases when IPv4 was developed, namely:

• The lowest address in each of the IPv4 subnets, currently used as a duplicate.
• 240/4, except 255.255.255.255
• 0/8, except 0.0.0.0
• 127/8, except 127/16

Schoen notes the lowest address category could be unreserved without problems. The others would require some coding changes.