1.3. Why Do We Need IPv6?
For historic reasons, organizations and government agencies in the United States use approximately 60 percent of the allocatable IPv4 address space. The remaining 40 percent is shared by the rest of the world. Of the 6.4 billion people in the world, approximately 330 million live in North America, 807 million in Europe, and 3.6 billion in Asia. This means that the 5 percent of the world's population living in the United States has 60 percent of the address space allocated. Of the 3.6 billion people living in Asia, approximately 364 million have Internet access, and the growth rate is exponential. This is one explanation of why the deployment of IPv6 in Asia is much more common than in Europe and the United States. (All statistics are based on 2005 numbers.)
The IPv4 address space has a theoretical limit of 4.3 billion addresses. However, early distribution methods allocated addresses inefficiently. Consequently, some organizations obtained address blocks much larger than they needed, and addresses that could be used elsewhere are now unavailable. If it were possible to reallocate the IPv4 address space, it could be used much more effectively, but this process is not possible, and a global reallocation and renumbering is simply not practical. We also have to be aware of the fact that today, as the IPv4 address space approaches exhaustion, only about 14 percent of the world's population has Internet access. If we want to provide Internet access to only 20 percent of the world's population, we will need the IPv6 address space. And this calculation does not take into account that in the future we will need IP addresses for billions of devices. Vendors in all industries are developing monitoring, control, and management systems based on IP.
As the previous section shows, the IPv6 working group has done more than extend the address space. For many complex networks of today and tomorrow, and for the number of IP devices of all types, the autoconfiguration capability of IPv6 will be a necessity. The management of such services can't be accomplished with traditional addressing methods, and Stateless autoconfiguration will also help to reduce administrative costs for organizations.
The extended address space and the restoration of the original end-to-end model of the Internet allows for the elimination of Network Address Translation (NAT), in which a single or a few public IPv4 address(es) are used to connect a high number of users with private addresses to the Internet by mapping the internal addresses to the public address(es). NATs were introduced as a short term fix for solving the address space limitations with IPv4, since IPv6 was not ready yet (refer to RFC 1631; the original NAT specification was obsoleted by RFC 3022 in 2001). NATs have become pretty common in IPv4 networks, but they create serious disadvantages in management and operation: in order to do the address mapping, NATs modify end node addresses in the IP header. Very often, application level gateways (ALG) are used in conjunction with NAT to provide application-level transparency. There is a long list of protocols and applications that create problems when used in a NAT environment. IPsec and peer-to-peer applications are two well-known examples. Another known issue with NAT is the overlapping of private address space when merging networks, which requires either the renumbering of one of the networks or the creation of a complex address mapping scheme. The amplification of limited address space, the primary benefit of NAT, is not needed with IPv6 and therefore is not supported by design.
By introducing a more flexible header structure (extension headers), the protocol has been designed to be open and extensible. In the future, new extensions can easily be defined and integrated in the protocol set. Based on the fact that IPv4 has been in use for almost 30 years, the development of IPv6 was based on the experience with IPv4 and focused on creating an extensible foundation; you can expect it to last a long time.
Broadband penetration rates in countries such as South Korea, Japan, Germany, France, and the United States continue to accelerate and, in some cases, have reached 65 percent or more. In fact, a 2004 study done by Nielsen//NetRatings (http://www.nielsen-netratings.com) showed that the city of San Diego, California had a broadband penetration rate of 69 percent. This level of always-on connectivity with substantial bandwidth capacity (when compared to dial-up services) means that there is greater opportunity for devices to be connected. And many consumer electronic manufacturers have taken advantage of this. Online gaming is no longer the sole purview of games on PCs. Gaming stations, such as Sony's PlayStation 2, the Nintendo DS, and Microsoft's Xbox, have added capabilities to take them online. In Japan, many telecommunication carriers are providing television-type services (movies, audio content, etc.) over their IP networks. Even appliances, such as refrigerators, stoves, water heaters, and bathtubs are getting connected. While it may seem rather silly to network-enable a bathtub, many of these devices are being connected to facilitate things such as power management, remote control, and troubleshooting, and for telemetry/monitoring purposes. The end result of this network-enablement process is a greater number of devices that need addressing, many of which will not have standard user interfaces. In these cases, the IPv6 address space, coupled with features such as Neighbor Discovery, autoconfiguration, and Mobile IPv6, will help to usher in a new era of computerization in the home, but hopefully without the enormous deployment headache that it would cause if it were attempted with the current protocol.
The growth of the wireless industry (both cellular and wireless networks based on protocols such as 802.11x, 802.16, 802.20, UMTS, UWB, MIMO, etc.) has been nothing short of phenomenal. In some countries, such as Italy and Great Britain, the number of cell phones actually exceeds the number of people. In this world of continuous reachability and reliance on the ability to access information at any time, the mobility requirements for end users have become exceptionally important. From the carriers' perspective, especially those supporting multiple media access types (e.g. 3G and WiMax), leveraging IP as the method of transporting and routing packets makes sense. Cell phones and PDAs can already access the Internet, play games with other users, make phone calls, and even stream video content. Instead of supporting all of these functions using different transport protocols and creating intermediary applications to facilitate communications, it is far more efficient to leverage the existing network infrastructure of the Internet and a company's network. We will see later that from a technical perspective, Mobile IPv6 is very elegant in its design, supporting mobile users in a highly efficient manner and providing the overlay mechanisms for users to maintain their connections when moving between networks, even if those networks do not use the same type of media access.
For many of the reasons discussed here, much of the world is already adopting IPv6. There has been significant adoption in Japan and Korea, with production networks and consumers paying for IPv6-based services. China is spending millions of dollars (USD) developing a new backbone network that is reportedly going to be IPv6. The European Union (EU) has also spent millions for the research and development of IPv6 backbone networks and innovative services that leverage many of the beneficial features of IPv6. India, with a growing middle class and a strong presence in the world of IT, has demonstrated substantial interest in the deployment and use of IPv6. In June 2003 and then again in July 2005, the U.S. government mandated the adoption of IPv6. Other countries such as Australia, Taiwan, Singapore, England, and Egypt have all made similar announcements. So IPv6 is on its way, and it happened faster than we expected when we published the first edition of this book.
There still remain some questions about the value of IPv6 to the enterprise, and it is worth conceding that each organization needs to evaluate the benefits of IPv6 carefully for their own internal use and determine the best time for its introduction. In many instances, organizations can find clever ways to use IPv6 to solve "pain" issues without migrating their entire network. Adoption can occur in an incremental fashion with a plan that minimizes integration pain but also ensures that everything is ready when the time comes to "flip the switch." As the case studies in Chapter 10 show, well-planned introduction costs less than you would expect; the step-by-step introduction allows you to learn as you go, thereby saving a lot of money and headaches, and you can do it without putting the current IPv4 infrastructure at risk.
But with all these thoughts and considerations, let's not forget the most essential advantage of IPv6. With its new structure and extensions, IPv6 provides the foundation for a new generation of services. There will be devices and services on the market in the near future that cannot be developed with IPv4. This opens up new markets and business opportunities for vendors and service providers alike. The first-mover opportunities are substantial, as are the opportunities to extend current product lifecycles by refreshing their technology with IPv6. On the other hand, it means that organizations and users will require such services in the mid-term. It is therefore advisable to integrate the new protocol carefully and in a nondisruptive manner, by taking one step at a time to prepare the infrastructure for these new services. This protects you from having to introduce a business-critical application based on IPv6 with no time for thorough planning and unreasonably high cost.