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IPV6: The Next generation of IP Adressing

The main improvement brought by IPv6 (Internet Protocol version 6) is the increase in the number of addresses available for networked devices, allowing, for example, each cell phone and mobile electronic device to have its own address. IPv4 supports 232 (about 4.3 billion) addresses, which is inadequate for giving even one address to every living person, much less for supporting the burgeoning market for connective devices. If one considers that the need to account for network topology in assigning addresses means that some are not available for use in practice, it becomes apparent that the shortage is greater than this simple reckoning would indicate; it is, however, lessened somewhat by the use of technologies such as network address translation. IPv6, however, supports 2128 addresses; this is approximately 5×1028 addresses for each of the roughly 6.5 billion people alive today.

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		IPV6: The Next generation of IP Adressing The main improvement brought by IPv6 (Internet Protocol version 6) is the increase in the number of addresses available for networked devices, allowing, for example, each cell phone and mobile electronic device to have its own address. IPv4 supports 232 (about 4.3 billion) addresses, which is inadequate for giving even one address to every living person, much less for supporting the burgeoning market for connective devices. If one considers that the need to account for network topology in assigning addresses means that some are not available for use in practice, it becomes apparent that the shortage is greater than this simple reckoning would indicate; it is, however, lessened somewhat by the use of technologies such as network address translation. IPv6, however, supports 2128 addresses; this is approximately 5×1028 addresses for each of the roughly 6.5 billion people alive today.
		By the early 1990s, it was clear that the change to a classful network introduced a decade earlier was not enough to prevent the IPv4 address exhaustion and that further changes to IPv4 were needed[1]. By the winter of 1992, several proposed systems were being circulated and by the fall of 1993, the IETF announced a call for white papers (RFC 1550) and the creation of the "IPng Area" of working groups[1] [2]. IPng was adopted by the Internet Engineering Task Force on Jul 25, 1994 with the formation of several "IP Next Generation" (IPng) working groups[1]. By 1996, a series of RFCs were released defining IPv6, starting with RFC 2460. (Incidentally, IPv5 was not a successor to IPv4, but an experimental flow-oriented streaming protocol intended to support video and audio.)
		Features of IPv6
		To a great extent, IPv6 is a conservative extension of IPv4. Most transport- and application-layer protocols need little or no change to work over IPv6; exceptions are applications protocols that embed network-layer addresses (such as FTP or NTPv3; NTPv4 supports IPv6). However, most applications need small changes or at least need to be recompiled with IPv6 supporting libraries. High level scripts and some well designed applications might work unchanged. The main feature of IPv6 that is driving adoption today is the larger address space: addresses in IPv6 are 128 bits long versus 32 bits in IPv4. IPv6 was designed to allow the bottom 64 bits to be set to the MAC address of the network card of the computer and the top 64 bits would be used for routing purposes. The top 64 bits are divided into four 16-bit groups, allowing for four levels of address delegation, for example from IANA to ISPs to companies to departments. These large blocks make administration easier and avoids fragmentation of the address space, which in turn leads to smaller routing tables. Since each host on a network segment can use the bottom 64-bits of the IPv6 address, the minimum allocation to companies or users will be a /48, leaving 16bits-worth of subnets; that is, each "enterprise" will have ~64k LANs to allocate as they see fit. Larger companies and ISPs will be allocated /32 or larger blocks. The larger address space avoids the potential exhaustion of the IPv4 address space without the need for NAT and other devices that break the end-to-end nature of Internet traffic. The drawback of the large address size is that IPv6 is less efficient in bandwidth usage, and this may hurt regions where bandwidth is limited. Another advantage of the larger address space is that it makes scanning certain IP blocks for vulnerabilities significantly more difficult than in IPv4, which makes IPv6 more resistant to malicious traffic. This apparent advantage is somewhat blunted by distributed attack techniques and access to the very techniques that will enable users and devices to connect in IPv6 — with such things as all hosts multicasts and Directory Service tables which will list which IPv6 addresses in the range actually have machines attached. Similarly, when new spoofing techniques are invented it will be much harder to track down rogue malware machines, especially if they are unlisted. Original Article here Other usefull IPV6 links: O'Reily Network: IPv6: Revitalizing the Internet Revolution: here



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Features of IPv6