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TCP/IP Tutorial and Technical Overview - IBM Redbooks

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9.1 <strong>IP</strong>v6 introduction<br />

9.1.1 <strong>IP</strong> growth<br />

Internet Protocol version 6 (<strong>IP</strong>v6) is the replacement for version 4 (<strong>IP</strong>v4). This<br />

section discusses the exp<strong>and</strong>ed address space capabilities of <strong>IP</strong>v6 <strong>and</strong> includes<br />

a brief feature overview.<br />

The Internet is growing extremely rapidly. The latest Internet Domain Survey 1 ,<br />

conducted in January 2006, counted 395 million hosts (374,991,609 hosts to be<br />

exact).<br />

Figure 9-1 The total number of <strong>IP</strong> hosts growth<br />

The <strong>IP</strong>v4 addressing scheme, with a 32-bit address field, provides for over 4<br />

billion possible addresses, so it might seem more than adequate to the task of<br />

addressing all of the hosts on the Internet, since there appears to be room to<br />

accommodate 40 times as many Internet hosts. Unfortunately, this is not the<br />

case for a number of reasons, including the following:<br />

► An <strong>IP</strong> address is divided into a network portion <strong>and</strong> a local portion which are<br />

administered separately. Although the address space within a network may<br />

be very sparsely filled, allocating a portion of the address space (range of <strong>IP</strong><br />

addresses) to a particular administrative domain makes all addresses within<br />

that range unavailable for allocation elsewhere.<br />

1 Source: Internet Software Consortium (http://www.isc.org/)<br />

328 <strong>TCP</strong>/<strong>IP</strong> <strong>Tutorial</strong> <strong>and</strong> <strong>Technical</strong> <strong>Overview</strong>

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