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IPv4 or IPv6—Myths and Realities

Chapter Description

Is IPv4 running out of addresses? Does IPv6 support multihomed sites? Does IPv6 provide increased security? The authors answer these questions and more.


The key takeaway of this chapter is that IPv6 represents an evolution of IP, not a revolution. Its development reflects the lessons learned from IPv4 and the requirements of today's Internet. The primary benefit comes from increased resources, not from radical protocol changes, as sometimes claimed. The original design goals of the new protocol were also very specific about enabling a smooth transition over the years and facilitating a long-term coexistence of IPv4 and IPv6. The commonly asked questions related to IPv6 that were answered in this chapter are summarized in Table 2-4. They provide a realistic perspective on the protocol.

Table 2-4. Summary of Commonly Asked IPv6 Questions



Is IPv4 running out of addresses?

Yes. Current estimates indicate this will occur between 2010 and 2012.

Are NAT benefits lost when moving to IPv6?

No. Even though NAT is not available, its true or perceived benefits can be implemented in IPv6.

Is IPv6 improving routing?

No. Routing protocols for IPv6 are equivalent to their IPv4 counterparts.

Will the size of the Internet routing table be a problem for networking equipment?

No. New generations of routers can handle the growth of the Internet routing tables.

Does IPv6 support multihomed sites?

Yes. At protocol level, IPv6 can implement multihoming in the same way as IPv4. Challenges might be due to allocation policies.

Does IPv6 deliver plug-and-play autoconfiguration?

Yes. IPv6 offers unique autoconfiguration mechanisms.

Does IPv6 offer better QoS?

No. At this time, the IPv6 and IPv4 QoS implementations are similar.

Is IPv6 required for mobility?

No. However, IPv6 does implement improvements to the Mobile IP protocols.

Does IPv6 provide increased security?

No. Most security threats and mitigation policies are similar to IPv4.

Is renumbering easier with IPv6?

Yes. Some IPv6 features simplify renumbering; however, they do not address all aspects of renumbering.

As discussed, the IPv4 address space cannot sustain the growing number of Internet users and the many new ways in which the Internet is facilitating today's communications. This evolution was not envisioned by the initial developers of the TCP/IP protocol suite. The only real option to address the growth pressures faced by IP is IPv6, and the case for its adoption is made in this chapter. Although IPv6, similar to IPv4, is a live and evolving protocol, it has already reached the level of maturity needed for safe, large-scale deployments. In recognition of a need for IPv6, organizations worldwide are already deploying it or aggressively planning its deployment.