Is IPv6 inevitable?

No. NATs could be used to solve the problem. I just hope that they aren't. I think we will have a better Internet if we go to IPv6 rather than NAT upon NAT. IPv6 is happening in China, Japan and Korea. The U.S. Defense Department is going to IPv6. I think you'll know that IPv6 is reaching the tipping point when content providers make their stuff available on both IPv4 and IPv6. When the content providers tool up for an IPv6 population that will help with [building a critical mass.] I will be very interested to see which content providers are accessible tonight. Google has publicly accepted the challenge to support IPv6 by the time they host our IETF meeting in Minneapolis in November. We haven't heard from Yahoo or MSN. We will see tonight if their sites are accessible on IPv6.

What's the risk for a company or government agency that doesn't switch to IPv6 soon?

In the next two years, probably nothing. After that, it's going to get harder to get the IPv4 addresses they need to grow their networks and that's when the economics will kick in. Do they spend money to obtain additional IPv4 address space by buying it from others? Or do they spend money investing in IPv6? IPv6 will be a one-time cost whereas as IPv4 gets scarcer and scarcer, it's going to continue to cost more and more each time they need more addresses.

If you were giving a speech to a room full of CIOs, what advice would you give them about IPv6?

Deploy it sooner so you can have it installed and it will be robust and your people will be trained before it's a crisis. The timeframe for that is two to two-and-a-half years. There's a capital expense to get the equipment to do IPv6 versus an operational expense to buy additional IPv4 address space. You're going to pay one way or the other. The capital expense for IPv6 will move you to a place where Internet addresses are plentiful.

Why is the IETF leadership so much more serious -- panicky even -- about IPv6 today than it was a few years back?

We're concerned because we're getting closer to the place where the IPv4 spigot runs dry. A very small percentage of the people here think that IPv4 trading will delay the need for IPv6. If that path comes to happen, the per-packet cost of the Internet will go up and the lack of plentiful Internet addresses will make it harder for places that don't have infrastructure such as Africa or South America to get involved in the Internet. Describing us as panicky is fair.