General question on rfc1918

Joe Abley jabley at
Tue Nov 13 15:10:26 UTC 2007

On 13-Nov-2007, at 10:08, Drew Weaver wrote:

>        Hi there, I just had a real quick question. I hope this is  
> found to be on topic.
> Is it to be expected to see rfc1918 src'd packets coming from  
> transit carriers?

You should not send packets with RFC1918 source or destination  
addresses to the Internet. Everybody should follow this advice. If  
everybody did follow that advice, you wouldn't see the packets you are  

The cynical answer, however, based on observation of real-life  
networks, is "yes" because people are naturally messy creatures.

> We have filters in place on our edge (obviously) but should we be  
> seeing traffic from and et cetera hitting our  
> transit interfaces?
> I guess I'm not sure why large carrier networks wouldn't simply  
> filter this in their core?

I can think of lots of things that large carrier networks (as well as  
smaller, non-carrier networks!) do that seem on the face of it to defy  
explanation, of which this is just one example :-)


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