Important IPv6 Policy Issue -- Your Input Requested

Leo Bicknell bicknell at ufp.org
Mon Nov 8 20:20:21 UTC 2004


In a message written on Mon, Nov 08, 2004 at 03:08:13PM -0500, Joe Abley wrote:
> I don't know of any applications that require RFC1918 addresses to be 
> deployed. (Clearly, this is not to say there are none.)

By "applications" I did not mean "software programs" but rather
"methods of designing networks".

> I know of lots of networks that use RFC1918 addresses because of a 
> (perceived, whatever) scarcity of IPv4 addresses, but presumably that 
> argument doesn't necessarily follow for v6 networks, where ever 
> customer site gets a /48.

A company may change providers often and want to use 1918 style space
to not have to renumber part of the network, or may choose IPv6 NAT
as superior to overlay networks.  Indeed, I suspect overlay networks
are going to be hugely unpopular.

> This sounds like a direct path to IPv6 NAT.

While I do not encourage IPv6 NAT, anyone who thinks IPv6 will put the
NAT Genie back in the bottle is smoking some serious crack.  Lots of
people like NAT for lots of reasons, and I am 100% positive there will
be IPv6 NAT used by a lot of people.

One obvious use if these proposals pass is to use your non-routable
global unique prefix internally and NAT at the borders.  Since a lot
of people think this is effective security, I think it will be a common
configuration.

> Perhaps the non-availability of RFC1918 addresses would provide a 
> useful incentive for future v6 network architects to install 
> globally-unique addresses on all hosts? Perhaps I am the only one that 
> thinks that would be a good thing ;-)

Many people share your opinion, and I think it is a good one to
voice.  That said at the end of the day most engineers are going
to treat IPv6 as "IPv4 with bigger addresses".  I know most of the
IPv6 proponents just wrote me off as a loon by saying that, but I
do believe it's reality and you need look no further than the
existing test networks to see that it's the case.  People who have
become used to CIDR, and NAT and such aren't going to forget those
idea's because someone told them "rigid boundaries are good" and
"you don't need private space anymore".

-- 
       Leo Bicknell - bicknell at ufp.org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/
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