V6 has been around
for quite a while. The IETF [Internet Engineering Task Force]
standardized it some time ago, but it hasn't rolled out in any
production sense, because the people who consume Internet resources
-- the ISPs and their customers -- have not been beating up on the
equipment vendors, demanding V6.
So, Cisco (CSCO)
was very reluctant to spend a lot of time and energy trying to get
the production of V6 going until they heard an ISP saying, "I need
it, I will pay for it, I won't buy your stuff anymore if it doesn't
So I finally went over to Cisco, not too long ago, at the
invitation of their CTO, and we just sat down and we all talked
about what the situation was, where VG6 was, what the pressure
points were, and why this was an issue for me. I came away feeling
as if I had officially raised the attention. They said, "Nobody's
asking for this," and I said, "I am. I'm an ISP and I'm asking."
UpsideToday: What must happen for V6 to be deployed?
Cerf: It's deployed in experimental form or sort of a test
form in a number of places. We run it in something called the VBNS,
which is a very high performance backbone network service. We built
that for the National Science Foundation in October 1994. That
network caters to mostly the R&D and university communities.
So we run V6 in that network using Cisco software. A number of
other vendors and ISPs are participating in something called the
Six-Bone, which is sort of a spin-off of the M-Bone. The M-Bone is
the multicast backbone and the Six-Bone is the IPV6 backbone. So a
bunch of us have been running V6 for a while.
But it's one thing to run V6. It's something else to figure out a
transition strategy that actually lets people run in mixed modes,
lets V4 and V6 interwork, and lets you spread more and more V6 as
time goes on.
I've asked my engineers to start working on transition strategies
and interoperability tests to see how well we can actually handle
the V4 to V6 exchanges. Much to my surprise, in June of last year,
the Internet Architecture Board invited a group to look at IP
Version 6 and to see what the scenarios might be in the future.
UT: Is one service provider going to have to step forward and
say, "We're going to do this. We're going to go to V6."
Cerf: I think that there's going to have to be one of
those. Everybody's standing around waiting for somebody to jump in
the pool, and I think that the pressure will build.
The thing that's going to push us over the hump, I think, will be
cable set-top boxes and cell phones that are Internet-enabled, you
know. When Nokia starts cranking out 80 million cell phones, and
then somebody else starts cranking out 80 million set-top boxes, and
they all want to be IP-enabled, where are they going to get the
Even if they don't run out, the guys who hand out IPV4 address
space are really parsimonious about it, because the IETF community
has given them a set of guidelines that allows them to be
parsimonious, so we don't run out of address space too quickly.
So what's the natural reaction? Well, ICANN [Internet Corp. for
Assigned Names and Numbers], the organization that oversees this
whole domain name and IP address allocation process, has officially
turned on IPV6 allocations, so now you can go and get a V6 address
space allocation, which we've done, for example, for VBNS. So the
process has begun.
There's a group called the IPV6 Forum that is trying to sound the
alarm, so to speak, to say it's time to get busy preparing for IPV6.
So at some point the vendors will hear that, and, I hope, will start
releasing production-quality V6 code.
And I hope that Microsoft will go beyond its current experimental
implementation of V6 in an NT framework and go all the way to
Windows, I don't know what, 2001 or 2002 production implementation
of V6. And of course many other people will have to do the same
thing. I believe that it's inescapable that we have to do something.
UT: Will people wait until it's more difficult than it need
Cerf: It's hard to say. I think that if you wait, you just
increase the long period of time over which you have to do
translations back and forth.
UTe: If all the ISPs are competing for address space, won't
ISPs that want to offer always-on DSL or cable modem have a business
incentive to go to V6?
Cerf: That's a good point, and I hadn't thought about
making that point to the ISPs in fact, but that's a good one. You
know, generically it's clear that you use up more address space with
all these on. But it didn't occur to me until you just mentioned it
that maybe that would be a good way of persuading other ISPs to go
UT: So, hypothetically, if one of them says, "We've made a
commitment to V6, so we're in a better position to support broadband
Cerf: Yeah. It's fair to point out, though, that if you've
got a V6 address and you want to be able to talk to anyone on the
Internet, somewhere the V6 address has to convert into V4. So the
ISP may be motivated, as you say, but the customer may have to buy
or the ISP may have to supply an NAT [network address translation]
box to be compatible with everybody else.