IPv6 is an upgrade to the Internet's main communications protocol, known as IPv4. IPv6 is needed because IPv4 is running out of addresses. However, IPv6 is not backward-compatible with IPv4. So network operators must run the two protocols side-by-side in what's called dual-stack mode or translate between them, which adds cost and latency to their operations. Because of these complications, IPv6 has suffered from a slow adoption curve. That's why Internet policymakers are promoting IPv6 through events such as World IPv6 Launch Day.
In addition to driving up IPv6-based Web traffic, World IPv6 Launch Day also saw a bump in IPv6-based email, with Google opening up Gmail to IPv6 and Comcast allowing some customers to send and receive email over it, too.
Comcast enabled its email infrastructure to support IPv6 in conjunction with Cloudmark, which reported that the first IPv6 email that Comcast received was spam. Cloudmark is pitching to ISPs a new way of filtering spam for IPv6 that involves tracking legitimate email senders rather than blacklisting spammers.
"Yes, our first IPv6 message was spam," Brzozowski said. "Deep down, I was hoping that it wouldn't be. Sadly, we had to wait a little while for a bona fide message that came over IPv6. ... We've taken our first step with IPv6-enabled mail with every intention that we will expand it over time."
Despite these increases over the last 24 hours, IPv6 represents a tiny share of overall Internet traffic.
Arbor Networks, which is monitoring IPv6 traffic across 15 service provider networks for World IPv6 Launch Day, said native IPv6 traffic rose to 0.1% of all Internet traffic in the first few hours of the event, which represented a 20% increase. Arbor said that IPv6 traffic has almost doubled in the year leading up to World IPv6 Launch Day.
"World IPv6 Launch Day is a starting point for providers to offer IPv6 services permanently going forward," explained Scott Iekel-Johnson, product manager for Arbor Networks. "The long-term trend is slow-and-steady increases since last year with native IPv6 traffic, which is what we want to see. The reason we didn't see a dramatic increase today is that the increase has been happening throughout the last week, the last month, the last year. That's why today is a relatively small bump."
Arbor did see a bigger bump for email, with 2.5% of all email going over IPv6 on Wednesday.