BCP38 exceptions for RFC1918 space

[randy at psg.com (Randy Bush)]

> What's the current consensus on exempting private network space from
> source address validation?  Is it recommended?  Discouraged?
> 
> (One argument in favor of exceptions is that it makes PMTUD work if
> transfer networks use private address space.)

and this is a good thing?  

rfc1918 packets are not supposed to reach the public internet.  once you
start accommodating their doing so, the downward slope gets pretty steep
and does not end in a nice place.

randy