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Re: Important IPv6 Policy Issue -- Your Input Requested

  • From: Joe Abley
  • Date: Mon Nov 08 15:09:53 2004

On 8 Nov 2004, at 14:53, Leo Bicknell wrote:

In a message written on Mon, Nov 08, 2004 at 02:36:21PM -0500, Joe Abley wrote:
Just out of interest, why do you think 1918-style space for v6 is
I think people have found many good uses for IPv4 1918 space, and
that it is likely they would want to migrate those applications as
directly as possible to IPv6.
I don't know of any applications that require RFC1918 addresses to be deployed. (Clearly, this is not to say there are none.)

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.

There is some value in RFC1918 addresses being used in v4 in cases where an extensive internal infrastructure is expensive to renumber, and PI addresses are not available. It is not clear that RFC1918 addresses are the only solution to this problem, though.

Since supporting that sort of migration
does not require a huge amount of address space or burden on the
addressing processes, I see no reason not to have 1918 space in
This sounds like a direct path to IPv6 NAT.

However, both of these proposals go well beyond how 1918 space works
today, and both make promises of "global uniqueness" that are at
best inappropriate, at worst a road to disaster.
Agreed, the proposals (as you outlined; I haven't read them) sound like they are full of holes.

However, I worry about any natural assumption that RFC1918-like addresses are required for v6, simply because they are used in v4: it seems to me that the major reason to deploy v6 is to eliminate the very address scarcity that RFC1918 addresses are used to mitigate.

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 ;-)