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Frequently Asked Questions on IPv6 adoption and IPv4 exhaustion

There have been several calls to action for organisations to plan actively for the widespread deployment of the new version of the basic Internet Protocol, IPv6, which is designed to supplement and eventually replace the 25-year-old IPv4 protocol. The Internet Society strongly supports such calls for action.

If deployment is delayed, the future growth and global connectivity of the Internet will be negatively impacted. The information below is intended to assist in answering some of the frequently asked questions associated with exhaustion of the IPv4 address pool and the adoption of IPv6.

This list of FAQs is intended to be a “living document.” It will continue to be updated and expanded.

Is the Internet about to run out of IP address numbers?

Yes and no. For the version of the Internet Protocol that underpins the Internet today (IPv4) there is a limited amount of unused space remaining. While estimates vary, based on recent trends it is anticipated that the current pool of unallocated IPv4 addresses will be consumed sometime around 2010 - 2011.

However, an enormous amount of IP address space exists under IPv6. IPv6, in fact, was specifically designed to fix the address limitations of IPv4. IPv6 addresses have been available for allocation since 1999 and the RIRs, ICANN, ISOC and others are encouraging network operators to apply for IPv6 addresses and implement IPv6 in their networks. Refer to the following announcements from:


What is IPv6?



Who created IPv6 and how long has IPv6 been available? Is it new?



What happened to IPv5?

Version 5 of the IP family was an experimental protocol developed in the 1980s. IPv5 (also called the Internet Stream Protocol) was never widely deployed. Since the number 5 was already allocated, this number was not considered for the successor to IPv4. Several proposals were suggested as the IPv4 successor, and each was assigned a number. In the end, it happened that the one with version number 6 was selected.


How does IPv6 solve the problem of IPv4 address exhaustion?





What happens when IPv4 address pool is finally depleted?

Existing devices and networks connected to the Internet through IPv4 addresses will continue to work as they do now. In fact, IPv4-based networks are expected to co-exist with IPv6-based networks at the same time.

However, for network operators and other entities that rely on Internet numbering allocations, it will become increasingly difficult and expensive (and eventually prohibitively so) to obtain new IPv4 address space to grow their networks. The cost and complexity associated with keeping track of and managing remaining IPv4 address space efficiently will also increase.

Therefore, network operators and enterprises will need to implement IPv6 in order to ensure long-term network growth and global connectivity.


When will IPv4 addresses actually run out?

The final allocations to the Regional Internet Registries (RIR) will soon be allocated. At current rates of consumption, the RIRs IPv4 address pools are likely to be depleted in approximately one year. The U.S. likely has less than a year left before *all* new networks will have to use IPv6 address space. Ahead of that date, the Internet Society and many global IT organizations are encouraging adoption of IPv6 and sponsoring World IPv6 Day in order to ready the industry for this necessary transition.


What’s the difference between IPv4 and IPv6? Will users be able to tell the difference?






Are there other advantages to IPv6 besides increased address space?



I've heard some people say IPv6 is more secure than IPv4, while others say it is less secure than IPv4. What is this about?

Debates concerning IPv4 versus IPv6 security often focus on different aspects of network deployment.

It has been said that IPv6 supports improved security because the specifications mandate the inclusion of the IP Security (IPsec) suite of protocols in products. In IPv4, including IPsec is optional, but it is commonly available. Because the IPsec protocol suite is designed to be indifferent to IP versions, the technology works generally the same way in both IPv4 and IPv6. In this way, the benefits of using IPsec are similar in either environment.

The increased address space provided by IPv6 does eliminate the need to use NAT devices, which are pervasive in many IPv4 networks. Broadly speaking, security is harder to deploy and troubleshoot when NATs are present in a network as they disrupt IP layer traceability and therefore security audit trails. In addition, the address rewriting that NAT performs is considered by some security protocols to be a security violation. Thus, with the increased address space eliminating the need to use NATs, IPv6 potentially facilitates deployment of end-to-end security.

Many of the IPv6 security issues reported today have to do with vulnerabilities in individual products, not the IPv6 protocol. IPv4 is widely deployed and individual IPv4 products have gone through the recurring cycle of discovering and fixing security vulnerabilities and other bugs. Because IPv6 products are comparatively new, they have not benefited from similar experience. Consequently, security vulnerabilities in IPv6 products will need to be discovered and repaired, just like for other products.

Also, the operational practices built up over many years for IPv4 networks will have to be adapted for IPv6. New practices will need to be developed for the dual stack IPv4 and IPv6 environment. This will be accelerated as more network operators deploy IPv6 and continue to exchange information about experience and best practices through established operators groups, the IETF Operations area, and other forums.

Overall, maintaining network security will continue to be a challenging undertaking in both IPv4 and IPv6 contexts. Neither protocol provides a simple solution to the complexities associated with securing networks. Like with IPv4, network operators should become educated on IPv6 security practices and keep up-to-date with developments as they plan for and deploy IPv6.


Is IPv6 ready for deployment now?

There are three basic aspects involved in the deployment of IPv6: the protocol, the products, and the operational practices.

The IPv6 Protocol

IPv6 has benefited from over 10 years of development within the Internet Engineering Task Force (IETF). The core standards have been stable for many years and deployed in both research and operational contexts. In addition to the core specifications, IPv6 includes a large number of individual standards that have a more limited applicability and are only needed in specialised environments. Additional development work will continue in these areas as new issues are discovered in response to deployment-specific scenarios. Like the continuing evolution of IPv4, there will always be updates and additions to IPv6 in response to deployment experience. Thus, even though the core IPv6 specifications are stable, there will continue to be ongoing work on IPv6-related specifications.

IPv6 Products

The core IPv6 specifications are becoming increasingly available as a standard part of products and service offerings. However, not all products are fully IPv6 capable at this time and some significant upgrade gaps remain, especially in low-end consumer equipment. Similarly, while many software applications and operating systems (especially in open source code) have already been updated for IPv6, not all products (including some from major vendors) are fully IPv6 ready. It is best to check with specific vendors on the IPv6 readiness of their individual products and services. In addition, in-house application software or custom code that interfaces with the network will likely need updating for IPv6.

IPv6 Operational Practices

Operational practices built up over many years for IPv4 networks will have to be adapted for IPv6. There is growing experience in the deployment of IPv6 in research networks and R&D projects, while some production networks (primarily in Japan and Korea) have been running IPv6 for a number of years. IPv6 traffic today, however, remains small in comparison to IPv4. As more network operators deploy IPv6 and continue to exchange information about experience and best practices through established operators groups, the IETF, and other forums, the community knowledge level will grow.

In summary, IPv6 is ready for deployment, but additional effort is needed to make its use pervasive. The IETF, equipment vendors, application developers, network operators and end users all have roles to play in ensuring the successful wide-spread deployment of IPv6.


So why has it taken so long for IPv6 to be implemented?


Has IPv6 been added to the root servers yet?



How much will the transition to IPv6 cost?




I have enough addresses today. Why should I bother implementing IPv6?




Is there a specific date when everything needs to be upgraded to IPv6?




Will IPv6 addresses run out eventually?



When will I need to turn off IPv4?

Possibly never. The purpose of deploying IPv6 is to ensure network growth and continued interconnectivity when IPv4 address space becomes depleted and difficult to obtain. In addition, as the global Internet continues to expand, it is likely that some Internet sites will only be available via IPv6.

To avoid problems, one should be fully IPv6-enabled by the time IPv6-only sites start appearing. However, in practice, it is only the public (or user) facing part of an enterprise's infrastructure that needs to be IPv6 enabled at the outset. The back-end infrastructure - which users do not interact with directly - can continue to be based entirely on IPv4, so long as that is the most cost-effective approach. (Enterprises may determine that it is more cost-effective to progressively turn off IPv4 in parts of their network once it is no longer needed or in significant use.)

One should expect, however, that it might never be cost-effective (or possible) to upgrade certain legacy systems. Thus, it will likely be a decade or more before enterprise sites find themselves in a position to consider completely turning off IPv4. In practice, there is no need to turn it off so long as IPv4-only applications still remain in use.


What does the IPv4 address depletion mean for enterprises and users? Should they panic?

There is absolutely no reason to panic. The existing IPv4 Internet will continue to function exactly as it does today.

There has already been considerable progress made - we have seen concrete progress from service and content providers to support IPv6. They know they are the ones to lead the charge and they are setting a great example for enterprises and other entities. We anticipate that adoption of IPv6 will accelerate so users do not notice the impact of IPv4 depletion. If migration decelerates, U.S. users might notice the impact within 12-18 months, but again, the momentum around this indicates we are well positioned to embrace IPv6 going forward. You can test your IPv6 readiness.


Will IPv4 address depletion mean that services will get switched off?


How long do you think we will have the IPv4 and IPv6 protocols active at the same time?



Isn’t address sharing the answer? We introduced NAT last time addresses were becoming scarce.


The sharing will be implemented at the service provider level in the form of large scale NATs. This means that users will find that they are sharing their IP address with a few hundred of their network neighbours at the same time. This will result in reduced performance and capabilities for end users, and higher costs and management complexity for service providers. The wide range of issues that address sharing creates have been documented by the IETF here:


I've been using NAT on my home network for years and it doesn't give me any problems. What's different this time?



Without NAT, won't my network be less secure?



What, specifically, still needs to happen for the industry to effectively transition to IPv6?

The transition to IPv6 will require collaboration across the Internet industry:



What’s going to happen on World IPv6 day?

Testing deployment readiness is a little bit of a chicken and egg issue – websites can’t test effectively without the networks and equipment vendors being ready and vice versa. World IPv6 day is the opportunity for the whole industry to test their readiness and to identify any areas for improvement during a 24 hour test flight.

IPv6 is extensively used in many large networks, but it has never been enabled at a global scale. IPv6 Day will help industry players work together to support the new protocol on an accelerated timeline. With major Web companies committing to enable IPv6 on their main Web sites, there are strong incentives for other industry players to ensure their systems are prepared for the transition.


For more information, including how to take part in World IPv6 day


How will IPv6 Day impact Internet users?



I run an ISP with a block of IPv4 address space. Can I just convert that into IPv6 space?




I run IT services. What should I be doing now to get ready?

Plan for IPv6 as you would for any major service upgrade.

Do an audit of your current IPv6 capabilities and readiness. Assess the level of IPv6 technical knowledge within your staff and make plans for staff development and training that will support IPv6 implementation.

Think about which of your services will lose business if they are only accessible to IPv4-users and make them a priority for IPv6 capability. For example, you may plan to implement an IPv6-enabled front-end Web server immediately, before converting your internal network.

Remove obstacles to enabling IPv6 including identifying any legacy systems that can not be upgraded, and choose a solution for them (most likely, the solution will be an application level proxy that can support both IPv4 and IPv6 for the remaining lifetime of that system). Plan upgrades and purchases so that you don’t find yourself needing to deploy and enable IPv6 but discover at a late stage that you are not ready because a key system dependency is not IPv6 capable.

Contact your vendors to find out about IPv6 support in their current products and future releases and ask your ISP about their plans to support IPv6.