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Re: A simple question

2003-04-19 12:28:12
On Sun, 20 Apr 2003 01:32:46 +0700, Robert Elz said:
    Date:        Sat, 19 Apr 2003 07:07:19 -0700
    From:        Dave Crocker <dhc2(_at_)dcrocker(_dot_)net>
    Message-ID:  <16890640984(_dot_)20030419070719(_at_)brandenburg(_dot_)com>

  | site local is, in fact, an addition to the IP architecture and that is
  | what is causing the controversy.

No, it isn't.   It is a cleaned up replacement for 1918 addresses.

Unbfortunately, I don't see where the biggest problems with 1918 addresses
were cleaned up for site-local.  Addresses will still leak out, and it
still has scoping problems.  You're still left wondering "Is this address
I was just handed an in-scope address from another part of my own network,
or is it a bogon I was handed by somebody else from part of THEIR net?"

The problems with 1918 space were well understood at the time:

   A major drawback to the use of private address space is that it may
   actually reduce an enterprise's flexibility to access the Internet.
   Once one commits to using a private address, one is committing to
   renumber part or all of an enterprise, should one decide to provide
   IP connectivity between that part (or all of the enterprise) and the
   Internet.  Usually the cost of renumbering can be measured by
   counting the number of hosts that have to transition from private to
   public. As was discussed earlier, however, even if a network uses
   globally unique addresses, it may still have to renumber in order to
   acquire Internet-wide IP connectivity.

   Another drawback to the use of private address space is that it may
   require renumbering when merging several private internets into a
   single private internet. If we review the examples we list in Section
   2, we note that companies tend to merge. If such companies prior to
   the merge maintained their uncoordinated internets using private
   address space, then if after the merge these private internets would
   be combined into a single private internet, some addresses within the
   combined private internet may not be unique. As a result, hosts with
   these addresses would need to be renumbered.

Unfortunately, people seem to want to forget about those two paragraphs. I'm
afraid that unless site-local includes a 'MUST renumber' requirement for *BOTH*
cases, it's a complete and total non-starter in my book.

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