In association with heise online

10 May 2008, 05:12

The mega network

Dusan Zivadinovic

IPv6 is becoming a reality

IPv6, the new version of the internet protocol, has existed side by side with IPv4 on popular PC operating systems since the advent of Windows Vista. This should herald the slow but timely demise of the IPv4 era, as IPv6 offers a number of advantages.

The development of Internet Protocol version 6, (IPv6), began in 1995, as it had already become obvious by then that the address space provided by the current standard (IPv4) would get tight. Early IPv6 implementations for PC operating systems appeared at the turn of the millennium (BSD), and IPv6 eventually made it into Mac OS X, Linux and finally into Windows. Vendors such as Cisco that manufacture routers for internet backbones have also long offered it as part of their product range. Some providers offer IPv6, and free PPP drivers for accessing providers are also available.

However, much to the disappointment of IPv6 enthusiasts, the protocol has so far failed to become mainstream. Backbone operators and providers both in the US and in Europe have hardly felt a need to rush – in these countries, most providers can access far more IP addresses than they have clients, which explains some of the lethargy which has so far prevented the general adoption of the protocol.

Deficiency ...

At the beginning of the internet era there was no need to worry about address space availability; the IPv4 specification offers 232 - that's about 4.3 billion - addresses, which seemed more than sufficient at the time. Nearly 640 million addresses were reserved for special purposes, and the rest were dished out very generously. The University of California in Berkeley (UCB), for example, was allocated about 16.8 million IP addresses which will hardly ever all be used.

As a consequence, large areas of these address spaces have been left unused but would be too cumbersome to reorganise. In addition, this would create only marginally more room - after all, IPv4 doesn't even provide enough address space to allocate at least one address to every human being. The shortage can already be felt in South America or Asia, where demand is currently increasing strongly, but only distinctly smaller address spaces are available. Therefore, various techniques are used to alleviate the problem, for example Classless Inter-Domain Routing according to RFC 1518 and RFC 4632 or various NAT varieties according to RFC 3022 and RFC 1918.

Zoom Enough space for every MP3 player and every washing machine: The IPv6 network boosts the address space to more than 340 sextillion IP addresses.

However, these are only small drops in the ocean. If the various forecasts are to be believed, the top level Internet Assigned Numbers Authority IANA will have distributed its last available IP addresses to regional associations on various continents within a few years' time; one of the most higly regarded studies predicts exhaustion in 2011. According to the study, regional IANA associations will have allocated all their address spaces to the providers by that time. Then, at the latest, internet users will begin to feel the consequences: when all IPv4 addresses are in operation at the same time, users without fixed IP addresses will have to wait until an IP address from the dynamically allocated space becomes available before they can access the internet. This should affect the vast majority of DSL surfers, but also users with modem, ISDN and mobile internet access.

... versus abundance

IPv6 defines a far greater address space of 2128 or 340 282 366 920 938 463 463 374 607 431 768 211 456 addresses, that's about 340.28 sextillion (in British units). This would be enough to pave every single square millimetre of the earth's surface including the oceans with about 600 quadrillion addresses. Since there is no reason to economise it is not only possible to furnish mobile telephones, vehicles or household appliances with their own IP addresses, but also to keep administration to a minimum by allocating addresses on the fly.

Many providers have quietly started to get ready for IPv6 - many ISPs already own IPv6 address space, although not all of them offer it to the general public or to private customers yet.

Among the big advantages of the IPv6 specification are, for example, IP auto-configuration via MAC address, renumbering for easier transfer of entire corporate networks between providers, jumbo programs for packet sizes up to 4 GBytes, faster routing, point-to-point IPSec encryption as well as retaining the same address across different networks (Mobile IPv6). These technologies will be explained in detail later.

The Multicast and Quality of Service technologies which were developed for IPv6 but later also integrated into IPv4 will be discussed in separate articles. Multicast replaces Broadcast technology and allows more efficient utilisation of bandwidth for video and audio streaming to more than one user. Quality of Service is used for prioritising data streams to prevent packet loss for time-critical applications. This is used, for example, in IP telephony to prevent delays or interruptions.

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