Re: Who does source address validation? (was Re: what's that smell?)

[Sean Donelan]

On Wed, 9 Oct 2002, Joe Abley wrote:
> What services require transport of packets with RFC1918 source
> addresses across the public network?
>
> I can think of esoteric examples of things it would be possible to do,
> but nothing that a real-world user might need (or have occasion to
> complain about).
>
> Do you have experience of such breakage from your own customers? It
> would be interesting to hear details.

Check the archives, its been covered every time this issue has come up...

   a. Intra-provider links using RFC1918 addresses and MTU changes/PMTU
discovery
   b. Traceroutes TTL exceeded packets across RFC1918 intra-provider links

People used to have lots of problems with @Home customers trying to access
their websites if their filtered RFC1918 addresses using large MTU
connected servers (i.e. non-ethernet).  Ok, so @Home is out of business,
but I'm sure there are other similar cases which would break.