Perry Lorier wrote:
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.
Yes, many IT depts will probably do that. IMO, that's fine. The IT
folks I know may not be fully versed in all the details of what NATs
break, but they know they break some things, and they know how to gather
enough information to make a decision about what's best for their
business. So IMO, if they think NATs are best for their situation,
that's fine. Often they don't want their users to have end-to-end
connectivity, and while I would be most upset if my ISP made that
decision for me, I can only really get upset about my employer doing it
if it negatively impacts my productivity somehow.
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.
The other possibility is that a heterogeneous corporation may decide to
use ULA-G space internally, NAT it at the edge, and also assign PA space
via DHCP or RA's wherever it's easy to do. If they can give 80% of
their users public IPs with only 20% of the effort, they can probably
just NAT the other 20% and be fine. As always, we have to just give
people the tools and the documentation about how to use them, and then
trust that they'll make a good decision for their particular situation.
-Scott
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