Important IPv6 Policy Issue -- Your Input Requested

Mon Nov 8 20:08:13 UTC 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
>> needed?
>
> 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
> IPv6.

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 ;-)

Joe