Re: Can a prefix be never routed on Internet but used only for source address in IP packets?

[Bill Woodcock via NANOG <nanog () lists nanog org>]

Sure. A large American mobile operator did that with a lot of their DNS traffic for a couple of months.  :-)

Of course you may be talking about doing it _intentionally_.  I don’t know of a reason to do it, but sure, it can be 
done. It’ll get dropped by anybody running uRPF. 
    
                -Bill


> On Aug 19, 2025, at 18:35, Sriram, Kotikalapudi (Fed) via NANOG <nanog () lists nanog org> wrote:
>
> Question:  Can a prefix be never routed on the Internet but used only one-way for source address in IP packets?
>
> That is. a user owns an IP prefix. They never advertise a route to it in BGP on the Internet. But they use the prefix 
> solely for source address in IP traffic from a source to a destination (sink).  In this set up, the destination 
> server obviously cannot/doesn't return any acknowledgements etc. to the source.  Anyone aware if there is any such 
> known application in use on the Internet - even if it is rare? Thanks.
>
> Sriram
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