On 27-mrt-2006, at 23:51, Austin Schutz wrote:
Your long term view is irrelevant if you are unable to meet short
term
challenges.
very true. but at the same time, it's not enough to meet short term
challenges without providing a path to something that is
sustainable in
the long term.
This is reasonable, but there is no realistic path to ipv6 that the
known world can reasonably be expected to follow.
Well, if you look at the rate at which the IPv4 address space is
being used up, something will have to give at some point. Last year
168 million IPv4 addresses were given out by the RIRs. That's about
4.5% of the 3706 million usable IPv4 addresses, with 60.2% gone as of
2006-01-01 and 1465 million addresses still available. (Give/take a /
8 because of inconsistent IANA/ARIN records.)
In the past 10 years, there have been several years where the growth
of the growth was less than the year before:
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
2.7 1.2 1.6 1.2 2.1 2.4 1.9 2.4 3.4 4.5
(The numbers represent the number of addresses used up in that year
as a percentage of the 3.7 billion total usable IPv4 addresses.)
Those years where the growth was smaller than the year before never
happened twice or more in a row.
This basically means that unless things take a radical turn, the long-
term trend is accelerating growth so that remaining 40% will be gone
in less than 9 years. Probably something like 7, as Geoff Huston
predicts.
When this happens, it will become extremely hard to find IPv4
addresses for new stuff, so many people/devices will have to share a
single address through NAT. Today, NAT mostly works because it's not
too hard to find someone who isn't NATed to coordinate the
communication. With IPv4 depleted that situation will change for any
new deployments, so NAT headaches will increase rapidly. (Bittorrent
with half the peers behind NAT is no problem. Bittorrent with all the
peers behind NAT is suboptimal. Bittorrent with everyone including
the tracker behind NAT makes you want to look up the meaning of
"sneakernet".) At that point, it becomes a no-brainer to add IPv6 to
bypass the IPv4 NAT and soon people who still have enough IPv4 space
will want to use IPv6 too because that gives them easier access to
people who don't have an IPv4 address.
At this point ISPs will want to provide IPv6 services too because
without that, IPv4-starved ISPs have a very hard time competing with
IPv4-rich ISPs. With IPv6 they're still not on an even footing but at
least the distance isn't as great.
In other words: even though we have significant NAT today, people who
need/want an unmolested IPv4 address today can have it without too
much trouble. When IPv4 addresses are gone, this will stop being the
case and IPv6 will start to look much more appealing.
It would also help if by that time all software would work over IPv6.
but the ipv6 vs. NAT battle is over in the marketplace.
For now. Even with NAT we need a constant supply of fresh IPv4
addresses, which we're not going to have forever.
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