[126112] in North American Network Operators' Group
Re: the alleged evils of NAT,
daemon@ATHENA.MIT.EDU (David Conrad)
Sat May 1 00:06:34 2010
From: David Conrad <drc@virtualized.org>
In-Reply-To: <B2B53111-1438-403F-9A81-C70BA19F6B13@delong.com>
Date: Fri, 30 Apr 2010 21:05:36 -0700
To: Owen DeLong <owen@delong.com>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Owen,
On Apr 30, 2010, at 7:04 PM, Owen DeLong wrote:
> Ideally, in the vast majority of cases, resolv.conf is populated by =
dhcpv6 or it's successor.
:-). I haven't been following the religious war against DHCPv6 -- is it =
now acceptable to get DNS information via DHCPv6? I note that MacOSX =
still doesn't appear to support DHCPv6. Does Win7?
> IPv6 also has the convenient concept of preferred and valid lifetimes =
on addresses facilitating a convenient overlap period while both =
prefixes still work, but, new flows should be universally originated =
from the specified prefix.=20
I'm aware of this. It would be interesting to see how many applications =
actually take advantage of this (rant about the socket API model =
deleted).
> There is a non-zero cost associated with renumbering. However, it is =
much closer to zero than in IPv4.
I agree that it can or at least has the promise to be.
> There is also a non-zero cost to NAT.
Yes.
> Unfortunately, the costs of NAT are more on the toxic polluter basis, =
where you must pay your own tab for renumbering.=20
End users must pay the cost of renumbering in both cases. With NAT, =
renumbering is done on the NAT box. Without NAT, renumbering must be =
done within the entire network. NAT can have an additional initial =
capital cost (although most CPE support NATv4 at no additional cost) and =
can have a potentially non-obvious additional opex cost associated with =
debugging network problems, application support, etc. =20
In the end, it would be nice if it was a simple business decision. In =
reality, I suspect most folks getting IPv6 prefixes from their ISP will =
follow the same model they use with IPv4 because that's what they know =
and it works for them. Hopefully, we'll see.
Regards,
-drc
