IPv6, ULAs and FreeBSD

Mark Tinka mark.tinka at seacom.mu
Fri May 27 05:54:34 UTC 2016

On 27/May/16 06:11, Kevin Oberman wrote:
> There are a lot of excellent reasons to avoid ULAs. There are a very few
> good, or even so-so reasons to use them. The most commonly cited reason is
> security which is almost always wrong. In almost 20 years of working with
> IPv6 I have yet to see any valid security reason for using ULAs. There are
> any number of excellent papers on this.
> The most valid use is when you can only get a /64 from your provider. RFCs
> recommend a minimum assignment to residential customers of a /56 but many
> providers seem to have missed this, so there is no choice. prefixes longer
> than /64 are effectively not possible. IPv6 does not care, but the
> supporting protocols , make a /64 or shorter assumption. More intractable
> is that hardware also often make similar assumptions. As you learned, you
> really, really don't waste your time trying to make it work.
> I really guess all of this needs to be in the handbook so people don't
> waste time trying to do things that are documented to either not work or
> not work effectively. And, unless you are really, really sure you need
> ULAs, They mostly just break things.

Fully agree.


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