It's seems we're always confusing NAT with PAT (or NAT overload, or whatever else you want to call it). One to one NAT rarely breaks stuff. NAT-PT would need to follow that model, otherwise, yes, things will break. It seems like an IPv6-only ISP would need to operate the NAT-PT boxes, and dedicate a block of v4 addresses the size of the expected concurrent online users to the NAT-PT box. Keep in mind that a v6 ISP with 1 million customers won't need a million v4 addresses, for obvious reasons. It's going to be considerably less than if each customer got a v4 address. NAT-PT does seem like a viable short term solution. I'm not sure though how to get current v4-only content providers to dual-stack their stuff. Increased domain fees maybe for v4-only domains... Chuck -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Iljitsch van Beijnum And then you'll see your active FTP sessions, SIP calls, RTSP sessions, etc fail.