I support Scott Brim's position, I understanding as: End-to-end transparency (the packet received is identical to that sent, including its source and destination addresses, but not including hop limit etc.) is a major component of the Internet's flexible and open-ended nature. We would need extraordinarily strong arguments to eliminate this from IPv6 - or to remove other such basis which may facilitate the development of applications we cannot yet imagine. Christian Vogt wrote: > Feynman is absolutely right, and certainly a network should enable > future, unknown applications. But your conclusion that end-to-end > locator transparency is a requirement to build such a network does not > convince me. I am not sure what "end-to-end locator transparency" means. "End-to-end transparency" is defined here: http://tools.ietf.org/html/rfc4924#section-1 in terms of "data" in the packet, but my definition involves the source and destination addresses, since these are typically important for how each host interprets the packet. I fully support: http://tools.ietf.org/html/draft-iab-ipv6-nat-00#section-4.1 We believe that providing end-to-end transparency, as defined above, is key to the success of the Internet. While some fields of traffic (e.g., Hop Limit) are defined to be mutable, transparency requires that fields not defined as such arrive un-transformed. Currently, the source and destination addresses are defined as immutable fields, and are used as such by many protocols and applications. My definition of end-to-end transparency is not affected by some function between the hosts which tunnels the packet to some intermediate device at "locator" address as part of efficiently forwarding it to the destination host. Any system such as NAT which changes the source or destination addresses of packets between hosts adds complexity and restrictions to what would otherwise be a clean, open, network. This was forced upon us with IPv4. If such changes to packets as seen by hosts is proposed as part of a scalable routing solution for IPv6, I think there would need to be robust arguments why any other scalable routing approach which preserved end-to-end transparency was impractical or for some very strong reason undesirable. The Richard Feynman quote is from "What Do You Care What Other People Think?: Further Adventures of a Curious Character (1988)". http://en.wikiquote.org/wiki/Richard_Feynman - Robin _______________________________________________ Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf