Today, most Internet traffic is served by Akamai, Google, Meta, and Netflix. These hypergiants deliver most of the content through globally distributed servers. These servers can be on-nets (within the hypergiant’s network) or off-nets (hosted in other networks, typically ISPs).
Off-net servers benefit both hypergiants and ISPs. For ISPs, they reduce user latency and enable them to cut costs as less traffic now crosses network boundaries. Hypergiants generate revenue and minimize bandwidth demand on on-net servers. Studying off-net deployment strategies is crucial as they alter traditional Internet traffic flows and could be vital for next-generation technologies like 5G that require low latency.
While off-net deployments have been relatively well studied in the IPv4 Internet, their IPv6 footprint has remained unclear until recently. With IPv6 deployment gaining traction, a similar study in the IPv6 Internet was necessary. To address this, I and researchers from TUM, LAAS-CNRS, and IPinfo performed a first-of-its-kind study of IPv6 off-nets for 14 hypergiants, including major players such as Google, Meta, Netflix, and Akamai, and compared their deployment over IPv4.
We found IPv6 off-nets in 2,000 networks, compared to the more than 6,000 off-net networks for IPv4. Google, Facebook, and Netflix have the largest off-net footprints, deploying servers in as many as 1,300 IPv6 networks alone. Moreover, most IPv6 off-net deployments are in networks that have already deployed IPv4 off-nets.
As a whole, we found that instead of choosing to exclusively deploy IPv6 off-nets in ISPs where there are no IPv4 ones, hypergiants are trying to match their IPv4 deployments.
What Fraction of Networks per Continent Deploy Off-nets?
We studied the top three hypergiants’ IPv6 off-net deployment per continent based on their off-net footprint (see Figure 1).
Our findings show North America has the highest fraction of IPv6 off-net covered networks for Google and Netflix, with around 20% of all IPv6 networks serving users in the region. Meta has the highest IPv6 network coverage in South America, with more than 30% of the networks covered.
For all top-three hypergiants, the worst IPv6 coverage, with 5%–13%, is in Africa. IPv6 outpaces IPv4 quite often, being the most prominent in Africa. As an exception to the IPv4 dominance, Meta has a higher IPv6 coverage in four continents, demonstrating Meta’s resolve to push IPv6 adoption.
Interestingly, we found the most networks, nearly 700 for IPv6 and more than 1500 for IPv4, deploying off-nets for these hypergiants in South America. Our findings reveal that this aggressive off-net deployment in South America stems from an underwhelming on-net presence of these hypergiants on the continent.
What Fraction of Internet Users Have ‘Access’ to Off-nets?
Although the number of networks covered by off-nets for a region might be small, the Internet user base served in the region can still be substantial if the off-nets are deployed optimally, that is, in networks that cater to a larger fraction of the user population.
For Google (see Figure 2), while IPv6 user population coverage is exemplary in Oceania and Europe and above average in the Americas, they can substantially improve it in Asia and Africa.
Meta’s coverage is smaller than Google’s in most regions (see Figure 3). For instance, Russia is largely underserved by Meta’s IPv6 off-nets, which are present in only two Russian networks—Vimpelcom, hosting IPv4 and IPv6, and AS Rostelecom, hosting only IPv4 off-nets. These have a collective market share of less than 1% in IPv6 and IPv4. Deploying IPv6 off-nets in networks such as Baxet and MTS can improve IPv6 coverage in Russia by more than 50%.
In regions such as China and Iran, known for censoring Facebook and Google, we found off-nets in less than 7% of the networks. In contrast, countries such as the US and those in Scandinavia had off-nets in up to 41% of the networks. Interestingly, we also found 40% of Chinese networks with off-nets for the Chinese hypergiant— Alibaba.
How Does IPv6 Off-net Performance Compare to IPv4?
We also evaluated and compared IPv4 and IPv6 off-net performance through latency-based measurements to reveal if IPv6 off-net deployments are at par with IPv4 ones, are catching up, or if significant room remains for improvement (see Figure 4).
Our findings reveal that the top hypergiants exhibited similar IPv6 and IPv4 performance for their off-nets, with most latency differences being under 5 ms.
Challenges and Future Work
Although we uncover IPv6 off-net deployments of several hypergiants, we acknowledge that our numbers for off-net hosting networks are a lower bound. This is owing to the vast number of IPv6 addresses, which makes a total address space scan infeasible.
In the future, we intend to curate a more representative list of IPv6 addresses to test more IP addresses for off-nets, potentially uncovering more networks with off-nets.
Finally, we intend to continue tracking the growth of hypergiants’ IPv6 off-net footprint and perform a longitudinal study in the future.
To learn more about this work, read our ACM CoNEXT 2024 paper, A First Look At IPv6 Hypergiant Infrastructure.
Fahad Hilal is a Doctoral candidate at MPI-INF focusing on Internet measurements in the IPv6 Internet.