Since there's no economic incentive to being the first to invest in revamping your protocol support, many hardware and service providers stood on the sidelines and waited for momentum to build.
For enterprises, it made no sense to upgrade to IPv6 if their ISPs were still running IPv4. As John Brzozowski, fellow and chief architect for IPv6 at Comcast Cable, puts it: We had a chicken-and-egg problem. "Service providers didn't want to implement IPv6 because the content providers weren't there, and content providers didn't want to implement it because the service providers weren't there."
Plus, there were ways to avoid having to face the IPv6 music. One common technique is carrier-grade network (CGN) address translation (NAT), which translates private IP addresses within a carrier's network to a smaller number of public IP addresses in much the same way that ordinary NAT lets individuals and organizations use multiple internal IP addresses.
However, CGN brings with it a number of issues that limit its appeal. For one thing, it's expensive for carriers, and the money they spend on it could be more productively applied to IPv6-ready hardware. For another, a great deal of Internet infrastructure relies on the premise that a single public IP address uniquely identifies a carrier subscriber. CGN breaks that assumption, which means that it breaks geolocation services and impedes law enforcement organizations' ability to identify users.
Carriers can also purchase surplus IP addresses from other carriers. ARIN has a well-defined process that lets organizations transfer IPv4 addresses. Some organizations have also transferred addresses without ARIN approval — what some have called a black market in IPv4 addresses.
ARIN is also helping to ease the pain by reclaiming unused addresses from, say, ISPs that have gone out of business, although that number is relatively small and won't materially affect the date upon which all IPv4 addresses are gone. ARIN is also now parceling out smaller and smaller blocks of IPv4 numbers and tightening the criteria for approval of new addresses.
But IPv4 workarounds will only last for so long and most organizations are recognizing that fact and moving, if grudgingly, to IPv6. Roberts says, "There's a light at the end of the tunnel."
Where are we headed?
Comcast recently announced that it now has the world's largest IPv6 deployment. In a post on Comcast's site, Brzozowski said, "Today, over 25 percent (and growing) of Comcast's Xfinity Internet customers are actively provisioned with native dual-stack broadband Internet service. Native IPv6 support has been deployed to over 75 percent of our broadband network, and our goal is 100 percent in early 2014."
Not all service providers have been as proactive, however. According to Internet Society measurements, Verizon shows no IPv6 presence.
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