The United States, however, is relatively flush with IPv4 address space. The American Registry for Internet Numbers (ARIN) has three /8 blocks of IPv4 address space left, which equals more than 50 million IPv4 addresses.
Many U.S. organizations also have large blocks of unused IPv4 addresses that they received at the dawn of the Internet, before anyone realized IPv4 addresses would become so valuable.
Peter Thimmesch, chairman of IPv4 address trading firm Addrex, says carriers around the globe continue to need IPv4 addresses for their dual-stack IPv6 deployments. "Carriers are taking a strategic view: they need to acquire enough IPv4 address space to support their customers for the many years it's going to take to deploy IPv6," he says. "It's about IPv4 and IPv6, not one or the other."
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