IPv4 address exhaustion is making it harder to measure the size of the Internet, even as IPv6 deployment accelerates.
While IPv6 activity doubled in 2015 (to 400 million addresses by year-end), the vast majority of users are still on IPv4 addresses, mostly via dynamic assignment or behind carrier-grade Network Address Translation (NAT) boxes.
Akamai and MIT researchers say the growth in the IPv4 address space hit the ceiling in 2014 and is stagnant at a little over 800 million (each month), and 1.2 billion unique addresses for the whole of 2015.
At APNIC, lead author Philipp Richter of Akamai and the Technical University of Berlin writes: “The stagnant active IPv4 client address counts, despite ongoing Internet growth, mark a new era of the Internet: one in which Internet growth cannot be tracked by counting active IPv4 addresses anymore.”
In their paper at Arxiv, the researchers explain the importance of address-based metrics. As well as helping ISPs and regulators plan for the future, addresses are used for:
- Reputation-based security systems;
- Address geolocation; and
- Network troubleshooting.
The researchers also find that static IPv4 addressing (the endpoint's address is fixed rather than being dynamically assigned from the ISP's pool) is wasteful.
“We find that more than 75 per cent of statically assigned address blocks show less than a quarter of the contained addresses as active”, the paper states. “Most dynamic address blocks, on the other hand, show activity for most or all contained IP addresses.”
It's quite likely that as address value rises, more static addresses will be returned by the organisations that hold them. As the paper notes: “While network restructuring can be cumbersome, it could certainly provide significant IPv4 address space utilisation potential”.
Richter's co-authors are MIT's Georgios Smaragdakis, David Plonka of Akamai, and Arther Berger of Akamai and MIT. ®