Private use of non-RFC1918 IP space

Valdis.Kletnieks at Valdis.Kletnieks at
Mon Feb 2 17:38:47 UTC 2009

On Mon, 02 Feb 2009 12:20:25 EST, "D'Arcy J.M. Cain" said:
> On Mon, 02 Feb 2009 18:03:57 +0100 (CET)
> sthaug at wrote:
> > > What reason could you possibly have to use non RFC 1918 space on a
> > > closed network?  It's very bad practice - unfortunately I do see it done
> > > sometimes....
> > 
> > There are sometimes good reasons to do this, for instance to ensure
> > uniqueness in the face of mergers and acquisitions.
> How does that help?  If you are renumbering due to a merger, couldn't
> you just agree on separate private space just as easily?

They don't renumber, they end up just double-NAT or triple-NAT betweem the
merged units.  I think one poor soul posted here that they had
quintuple-NAT'ing going on due to a long string of mergers....

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