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IPv6 Internet Protocol defines how computers communicate over a network. IP version 4 (IPv4), the currently prevalent version, contains just over four billion unique IP addresses, which is not enough to last indefinitely. IPv6 is a replacement for IPv4, offering far more IP addresses and enhanced security features. ARIN and the other RIRs have distributed IPv6 alongside IPv4 since 1999. So far, ARIN has issued both versions in tandem and has not advocated one over the other, though it has closely monitored distribution trends with the understanding that the IPv4 available resource pool would continue to diminish. With only 19% of IPv4 address space remaining with projected run out in 2010, ARIN is now compelled to advise the Internet community that migration to IPv6 is necessary for any applications that require ongoing availability of contiguous IP number resources. 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). Applications, however, usually need small changes and a recompile in order to run over IPv6. Larger address space 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. The larger address space avoids the potential exhaustion of the IPv4 address space without the need for network address translation (NAT) and other devices that break the end-to-end nature of Internet traffic. NAT may still be necessary in rare cases, but Internet engineers recognize that it will be difficult in IPv6 and are trying to avoid it whenever possible. It also makes administration of medium and large networks simpler, by avoiding the need for complex subnetting schemes. Subnetting will, ideally, revert to its purpose of logical segmentation of an IP network for optimal routing and access. The drawback of the large address size is that IPv6 carries some bandwidth overhead over IPv4, which may hurt regions where bandwidth is limited (header compression can sometimes be used to alleviate this problem). IPv6 addresses are harder to memorize than IPv4 addresses, although even IPv4 addresses are much harder to memorize than Domain Name System (DNS) names. DNS protocols have been modified to support IPv6 as well as IPv4. Stateless autoconfiguration of hosts IPv6 hosts can be configured automatically when connected to a routed IPv6 network. When first connected to a network, a host sends a link-local multicast request for its configuration parameters; if configured suitably, routers respond to such a request with a router advertisement packet that contains network-layer configuration parameters. If IPv6 autoconfiguration is not suitable, a host can use stateful autoconfiguration (DHCPv6) or be configured manually. Stateless autoconfiguration is only suitable for hosts: routers must be configured manually or by other means. Multicast Most environments do not currently have their network infrastructures configured to route multicast; that is — the link-scoped aspect of multicast (i.e., on a single subnet) will work but the site-scope, organization-scope and global-scope multicast will not be routed. IPv6 does not have a link-local broadcast facility; the same effect can be achieved by multicasting to the all-hosts group (FF02::1). The m6bone is catering for deployment of a global IPv6 Multicast network. Jumbograms In IPv4, packets are limited to 64 KiB of payload. When used between capable communication partners and on communication links with a maximum transmission unit larger than 65,576 octets, IPv6 has optional support for packets over this limit, referred to as jumbograms which can be as large as 4 GiB. The use of jumbograms may improve performance over high-MTU networks. Network-layer security IPsec, the protocol for IP network-layer encryption and authentication, is an integral part of the base protocol suite in IPv6; this is unlike IPv4, where it is optional (but usually implemented). IPsec, however, is not widely deployed except for securing traffic between IPv6 Border Gateway Protocol routers. Mobility Unlike mobile IPv4, Mobile IPv6 (MIPv6) avoids triangular routing and is therefore as efficient as normal IPv6. This advantage is mostly hypothetical, as neither MIP nor MIPv6 are widely deployed today.   Sample Ipv4 Our Primary DNS: 216.109.194.1 Sample IPv6 Our Primary DNS: 2610:90::81   Contact us today about getting ready for IPv6     References: Wikipedia ARIN

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