BCP38 exceptions for RFC1918 space

David Freedman david.freedman at uk.clara.net
Mon Aug 16 10:42:41 UTC 2010

Florian Weimer wrote:
> 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.)

IMHO, operators who number infrastructure out of RFC1918 and then permit
internet traceroutes over it are misguided and should consider avoiding
TTL decrement (i.e using mpls without internet TTL propagation) as a
less stressful (for us) alternative to simply filtering.


David Freedman
Group Network Engineering
Claranet Group

More information about the NANOG mailing list