Mysterious missing DHCPv6 feature, was Re: How does one obtain an IPv6 DNS server when VPNing to an ASA?

[Doug Barton]

On 5/27/2010 12:14 PM, Ted Mittelstaedt wrote:
>
> On 5/27/2010 6:53 AM, Gert Doering wrote:
>> Hi,
>>
>> On Mon, May 24, 2010 at 12:42:30PM -0700, Doug Barton wrote:
>>> I'm talking internal networks here. Lots of 1918 space available.
>>
>> I wonder why there's so much address collisions between VPN sites and
>> at enterprise mergers and acquisitions...
>>
>
> Because everyone uses 192.168.1.X since that's the default on
> most translators.

Right-O. Or 10.0.0.0/24, or what have you. At $SEVERAL_JOBS_AGO when we
were talking about setting up subnets for an isolated internal project I 
suggested using 172.16/12 since we weren't using any of that space at
the time, and I wanted the new thing to be clearly identifiable as
"other." I was told that we couldn't do that because those were public
addresses. Another time we were dealing with reorganizing some internal
networks for local and remote offices I suggested that we _start_ our
organizational plan at 10.200 and give each site their own /16. They
looked at me like I had 3 heads.

> The solution - renumbering - isn't going to go away after IPv6.
> When you have a merger you may get away with not immediately
> renumbering as a result of IPv6 but you almost certainly are going
> to be changing ISP's used at the acquired entity, and when you
> do that you will have to renumber the inside network.

... or it's just easier to have everyone under the same prefix, etc.
I've been on both sides of the M&A equation, so I think I understand the 
issues there pretty well.

My point being that IPv6 doesn't magically fix the renumbering problems
(such as they are) that exist in IPv4 today. It does make some things
easier, but it comes at a cost. The important thing is to do a
_realistic_ assessment of both the costs and the benefits.


Doug

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