IP4 Space

Dave Israel davei at otd.com
Wed Mar 24 09:49:32 CDT 2010

On 3/23/2010 10:59 PM, Mark Newton wrote:
> On 24/03/2010, at 4:10 AM, Christopher Morrow wrote:
>> it seems to me that we'll have widespread ipv4 for +10 years at least,
> How many 10 year old pieces of kit do you have on your network?

Are you kidding?  I'm in state education these days.  I probably still
have one or two 2500 series routers hiding in my network. 

> Ten years ago we were routing appletalk and IPX.  Still doing that
> now?

Ten years ago we were routing ipv4, which was going to die of address
exhaustion  and/or be replaced by ipv6 within two years.   Fifteen years
ago we were running ipv4, which was going to die of address exhaustion
and/or be replaced by OSI within two years.  I remember a (telco)
engineer, after a presentation on MPLS in the late 90s, saying that it
was all very interesting, but all this IP stuff was a fad, and
everything was going to be ATM in the near future.

> I'd expect that v4 will still exist in legacy form behind firewalls, 
> but I think its deprecation on the public internet will happen a lot
> faster than anyone expects.

You may be right; past experience is not always correct in predicting
future behavior.  But there has to be a reason why it will be different
this time.
>> I agree that v6 deployments seem to be getting
>> better/faster/stronger... I think that's good news, but we'll still be
>> paying the v4 piper for a while.
> Only until v4 becomes more expensive (using whatever metric matters to
> you) than v6.
> After you pass that tipping point, v4 deployment will stop dead.

Sure.  But the key phrase is "whatever metric matters to you."  You're
going to find people whose "expense" metrics are neither dollars nor sense.

1) For some people, that might mean what you think it means: "Hey, to
deploy ipv4, we have to pay for this expensive translator box.  Lets do

2) On the other hand, there'll be "Hey, we already bought the translator
box, because we had an emergency and had to deploy it.  So let's stick
to v4, because it is what we know." 

3) In a lot of places, there will be "Everything I want is v4. v6 is the
expensive option, because it means deploying new router software and/or

4) For others, it will be "I know v4, and not v6.  My management knows
nothing, and buys what I tell them."

5) Because of groups 2-4, there will be plenty of "Everybody else is
still doing v4, and so v4 is what I need to reach them."

6) And finally, there will be a lot of "I need to talk to people in
groups 2-5, so I need to deploy v4 regardless."

Remember, a new protocol is a lot harder to sell than a new hack that
makes the old protocol live longer.  And all the protestations of "It
can't keep going on like this" ignores history again.  Just because we
don't *want* NAT to be "fixed" to support more people doesn't make it
un"fix"able.  If you want v6 deployed, you cannot expect to sit around
and wait for everybody to admit you're right; you must make deploying v6
easier/cheaper/less painful than pumping life into v4.


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