On 19/03/2010, at 4:07 AM, Stan Barber wrote: > 1. Almost all home users (not businesses) that are connected to the Internet > today via IPv4 are behind some kind of NAT box. In some cases, two NATs (one > provided by the home user's router and one provided by some kind of ISP). > There is no need for this using IPv6 to communicate with other IPv6 sites.
There are a large number of users, here in NZ at least, but I imagine in other places, that have a single ethernet port "ADSL Modem" which terminates PPP, does IPv4 NAT, DHCP, etc. and then a "Wireless Router" which has its ethernet "Internet" plug connected to the "ADSL Modem", and does IPv4 NAT, DHCP to end hosts, etc. This means that they have double NAT inside the home, and then in the future a potential third NAT. We did some looking at packets, and 17% of outbound packets from customers at an ISP had TTLs that indicated two L3 hops in the home - which for the majority of cases would mean double NAT. In NZ the most popular ADSL deployment is PPPoATM, so the ADSL unit the ISP ships (either loaned, or included in the install cost) is an IPv4 router terminating a PPPoATM connection, not a bridge or anything. -- Nathan Ward
