IPv6 mistakes, was: Re: Looking for an IPv6 naysayer...

Steven Bellovin smb at cs.columbia.edu
Thu Feb 17 10:24:54 CST 2011


On Feb 17, 2011, at 9:44 04AM, John Curran wrote:

> On Feb 17, 2011, at 9:32 AM, Valdis.Kletnieks at vt.edu wrote:
> 
>> On Thu, 17 Feb 2011 08:08:50 EST, John Curran said:
>> 
>>> Rather than saying 240/4 is unusable for another three years, perhaps the
>>> service provider community could make plain that this space needs to be
>>> made usable
>> 
>> In other words, you're going to tell Granny she needs to upgrade to Windows 8
>> and/or replace her CPE because you couldn't get your act together and deploy
>> IPv6 - even though her friends at the bridge club who are customers of
>> your clued competitor didn't have to do a thing.
> 
> Not, what I'm saying is that we've been considering this matter for more than 
> 10 years, and as old as her machine is, it would have been patched once since
> then if we had bothered to note that "Reserved for Future Use" should be treated
> as unicast space.  
> 
> The same argument applies now: unless there is a reason to save 240/8, it should
> at least be redefined to be usable in some manner so that we don't repeat the 
> same argument 5 years from now.
> 
John, my usual rule of thumb for something like this is 8-10 years -- 3-5 years
for the next major version of Windows, plus (at least) 5 for enough old machines
to die off.  There are just too many machines that don't listen to Windows Upgrade;
you can't roll out a major change that way.  We won't even talk about things like
home NATs and cable/DSL/fiber modems, which tend to be longer-lived.

If we'd started this 10 years ago, as you suggest in a later note, maybe it would
be present in Windows 7, possibly even Vista.  So we'd be set -- Windows XP is
gone by now, right?  Oh, yeah, it isn't...  And as Valdis points out, it just
doesn't buy us that much time.

It might be worth doing for ISP backbones, and for things like tunnel endpoints.
For anything else, it's not worth the effort -- and I suspect never was.


		--Steve Bellovin, http://www.cs.columbia.edu/~smb









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