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cisco ccna badge.23.1.1 Scaling IssuesIn the early to mid 1990s, there was a growing concern about the imminent exhaustion of IPv4 addresses. An expedient solution to this problem was proposed, which was to set aside a space of addresses known as private addresses, in which addresses could be used by anyone on an internal network. As stated in Chapters 6 and 22, these addresses are defined in RFC 1918, and they are 10.0.0.0/8, 172.16.0.0.172.31.255.255, and 192.168.0.0.192.168.255.255. To access the public network, private addresses must be converted to public addresses using address translation: to allow external users to access internal services, network address translation (NAT) is typically used; to enable internal users to access external networks, port address translation (PAT) is typically used OHowever, the market has changed so much that soon address translation will not solve the problem either, and there will be no public addresses available for translation. Some companies are beginning to migrate to IPv6 for the following reasons. . Currently, more than 3 billion users are connected to the Internet; in emerging markets such as China and India, the number of people with Internet access is growing exponentially. . More than 2 billion mobile devices, such as smartphones and tablets, now provide common data services such as email and Web browsing; this number is expected to grow as more and more enterprises implement mobile applications. . The number of consumer products, such as cars and appliances, and industrial equipment that provide data services is growing, and the number of these devices is expected to grow into the billions.Clearly, the question is not whether and when the public address will run out, but how quickly that day will come. Some have predicted that IPv4 addresses will run out in 2008 or 2009, others in 2013, and now in 2014, IANA has very few IPv4 addresses available for manual allocation. Some countries have already moved to migrate to IPv6 o For example, as early as 2003, the U.S. Department of Defense mandated that all new network equipment must support IPv6; countries such as Japan and China are rapidly adopting the new standard IPv6 oChapter 23 IPv6 611Consider the technological changes that have taken place in the last decade: TV channels can now be switched via mobile phones and microwave ovens can be turned on remotely, and TV programs can be transferred to PCs and then stored on networked storage devices accessible by the TV; and these are just the beginning of such changes. To be able to communicate, all of these devices must have addresses, and most companies use TCP/IP to do so. Sony, for example, mandated in 2005 that all of its products must support IPv6o23.1.2 Characteristics of IPv6Clearly, to meet the growing demand, an alternative to IPv4 must provide a sufficient number of addresses,, but must also be easy to use and configure, more secure, and able to interoperate with IPv4 to ease the transition. Here are some of the features of IPv6.. Large address space: IPv6 has a large address space to meet growing global demand; easy aggregation of routing prefixes in routing updates; easy connectivity to multiple ISPs using a single address space; automatic configuration of addressing information, including MAC addresses in IP addresses and plug-and-play options, which simplifies address management; easy re-addressing and no need for Address translation to convert private addresses to public addresses is not required.. Security: IP security (IPSec) is built-in in IPv6, while it is a plug-in in IPv4. When using IPv6, two devices can automatically negotiate security parameters and establish a secure tunnel between them without user intervention. . Mobility: Mobile devices such as smartphones and tablets are increasingly able to roam between wireless networks without disrupting their connections.