Stephen Sprunk wrote:
Thus spake "Perry Lorier" <[EMAIL PROTECTED]>
Stephen Sprunk wrote:
One of the arguments by the anti-ULA crowd is that if someone is
unable to also get PI space, they will NAT their ULAs to PA space
rather than assigning the PA space to hosts directly, because NAT is
perceived as less hassle than renumbering every few months.
Except with v6 you can quite easily have multiple prefixes on an
interface. So you can have your ULA prefixes for your internal
services (dns servers, smtp servers, whatever) and use your globally
routable IPv6 addresses for IPv6 connectivity.
The fact that one _can_ assign both ULAs and PA space to hosts is
irrelevant; I'm well aware of that. NAT is perceived by IT folks as
less hassle than renumbering hosts. PA space implies frequent
renumbering. Therefore, many (most?) IT depts who cannot get PI space
will use NAT rather than assign PA space to hosts.
However in IPv4 you can have PA xor PI space, you can't have both at the
same time. With IPv6 you can have PA+"private PI" (aka ULA) space.
My router can dish out some different PA space every time my dialup
modem reconnects if my internal network is all using ULA internally.
I'm not really sure that situation really is "renumbering" in the
traditional sense even tho I'm not using NAT nor am I using public PI space.
Changing your PI space every time your modem dials up is perhaps a bit
extreme, but it shows that you can ""renumber"" your network rapidly in
some situations. Problems occur for externally facing services, but
that doesn't seem insurmountable for an organisation that's likely to
only change PI space at most every year or so.
If your choices are PI vs PA then yeah NAT does look very attractive,
but if you can have PA and "private"-PI (aka ULA) then things look a lot
less blurred (IMHO).
Not having ULA space won't stop people from randomly picking address
ranges to use. Not having NAT boxes easily available for v6 however
might make people rethink their assumptions.
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