Extranet with Overlapping Addresses

The idea to write an article describing how you can use MPLS VPN-enabled NAT to implement flexible extranets that allow participants to retain their existing (and sometimes overlapping) IP address space has been sitting in my to-do list for over a year.

After I’ve finally written it (without even hinting what I’ve been working on), I got several e-mails from my readers asking the questions this article answers, so it looks like the topic has suddenly become very hot. Do you have any ideas why that would be the case?

You’ll find the original article somewhere in this list.


  1. Growing awareness of IPv4 address exhaustion?
  2. This has nothing to do with IPv4 address exhaustion ... apart from the fact that we're all using private IP addresses internally, resulting in almost guaranteed address overlap when you have to join numerous independent private networks into an extranet.
  3. This comment has been removed by the author.
  4. mergers and acquisitions happening around..?
  5. It might be so that something that was considered a major network design flaw (overlapping IP addresses) now doesn't look so terrible and can be fixed with a standard (industrial) solution.
  6. Acquisitions in a battered economy.
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