North American Network Operators Group

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Re: Someones being naughty again...

  • From: Phil Howard
  • Date: Sat Mar 14 04:10:49 1998

> Offhand, I can't think of any other problems but I really discourage
> people from using internal address space for this purpose because it:
> 	- breaks stuff like path MTU discovery, etc. when filtered.

You also discourage people from filtering the ICMP packets this uses.

> 	- prevents easy identification of links, whose they are, etc.
> 	  because you can't have reverse DNS and the addresses don't
> 	  belong to you.

Not a problem if it is entirely inside an enterprise, as valid addresses
before and after it would be the same enterprise.  But as links between
I would see a problem.

> 	- causes confusion when multiple networks that are using such
> 	  addresses are merged or interconnected in the wrong (right)
> 	  way.

Private addressing is not the ideal solution, but when networks are built
with lots of links to lots of places, address allocating authorities
prefer you to use private addresses where feasible.  It maybe be a gray
and fuzzy line determining that, but many cases clear work fine with
such addresses (for example having a consisent MTU).

> I like the idea behind why you would do it, but... can't justify it.

I don't have so many links that I can't get them all in a /24.  But much
beyond that and I will be using private addresses.  I do run some private
address LANs, but they end in private addresses and you should never see
them (but if you are my customer you will be able to).

Phil Howard | [email protected] [email protected] [email protected]
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