Blaine Christian wrote http://www.faqs.org/rfcs/rfc3682.html I agree that it is not a panacea... But, you must admit, it provides an incredible level of comfort. It would be wonderful to only allow internally generated traffic to talk to the core of your network with a simple TTL filter. Versus anti-spoofing filters from hell.

That's not the way I see this at all. I look at it as a good complement to anti-spoofing filters as part of defense in depth, in case said filters get SNAFUed. My primary line of defense will remain ACLs. Michel.