Quote from <IPv6 Essentials Second Edition>:
For historic reasons, organizations and government agencies in the United States use
approximately 60 percent of the allocatable IPv4 address space. The remaining 40
percent is shared by the rest of the world. Of the 6.4 billion people in the world,
approximately 330 million live in North America, 807 million in Europe, and 3.6 bil-
lion in Asia. This means that the 5 percent of the world’s population living in the
United States has 60 percent of the address space allocated. Of the 3.6 billion people
living in Asia, approximately 364 million have Internet access, and the growth rate is
exponential. This is one explanation of why the deployment of IPv6 in Asia is much
more common than in Europe and the United States. (All statistics are based on 2005
numbers.)
The IPv4 address space has a theoretical limit of 4.3 billion addresses. However,
early distribution methods allocated addresses inefficiently. Consequently, some
organizations obtained address blocks much larger than they needed, and addresses
that could be used elsewhere are now unavailable. If it were possible to reallocate the
IPv4 address space, it could be used much more effectively, but this process is not
possible, and a global reallocation and renumbering is simply not practical. We also
have to be aware of the fact that today, as the IPv4 address space approaches exhaus-
tion, only about 14 percent of the world’s population has Internet access. If we want
to provide Internet access to only 20 percent of the world’s population, we will need
the IPv6 address space. And this calculation does not take into account that in the
future we will need IP addresses for billions of devices. Vendors in all industries are
developing monitoring, control, and management systems based on IP. |
发表于 26-8-2010 15:44:06
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