do that many networks really allow spoofing? i used to think so, based on hearsay, but rob beverly's http://spoofer.csail.mit.edu/summary.php suggests things are a lot better than they used to be, arbor's last survey echos same. are rob's numbers inconsistent with numbers anyone else believes to be true? i think you unfairly characterize UW's work, but i also think you make questionable inferences regarding the extent of spoofing, which seems more relevant to nanog. k On Fri, Sep 05, 2008 at 05:22:27AM +0000, bmanning@vacation.karoshi.com wrote: seems that some folks in the R&E community, with institutional support from Cisco, Google, and the US NSF, are exploiting our inability to take even rudimentary steps toward providing a level of integrity in routing by teaching students that spoofing IP space is ok. This whole thing works at all because so few people use/deploy/maintain BCP-38 compliance. This was an eye-opener for me. http://www.caida.org/workshops/wide/0808/slides/measuring_reverse_paths.pdf --bill