Hi, I've been aware of this draft for a while, and have begrudgingly felt that if any form of address translation is going to occur in IPv6 then the method described in this I-D was a good way to do it, as it avoids many of the drawbacks of many of the IPv4 NAT and NAPT methods. One area where I think there could be further discussion is the consequences of end-nodes not knowing their global address(es). There is mention about applications having trouble because of not being able to do referrals, as that is a well known problem in commonly deployed IPv4 NAPT. One of the high barriers in IPv4 NAPT for this to occur was the absence of a 1-to-1 mapping between external and internal addresses, as well as the absence of knowledge of which external ports are currently mapped to internal ports and vice-versa. This draft removes both of these significant limitations in IPv6 translation. I've only recently realised that what is really happening with address translation is that end-nodes lose their ability to know their global identity at the network layer (losing their ability to know their global addresses is the symptom, losing their ability to know their "global identity" is the consequence). If two end-nodes don't have global identities, they are forced to communicate, at least initially, via an intermediary which does have a global identity. End-nodes behind translators can't have a true peer-to-peer relationship at the network layer or above it if they don't know their own global identities. Yet my understanding is that a true peer-to-peer property of the network layer is one of the fundamental architectural design goals of the Internet's network layer protocols. While IPv4 NAT/NAPT limited that significantly, my hope has been that IPv6 restore that the network layer's true peer-to-peer nature, which requires end-nodes to know their own global identity. I think two other cases could be mentioned were trading of global identities are occurring at the transport layer, rather than the application layer - SCTP and multipath-TCP - and that their reliability and performance goals will also be effected by IPv6 prefix translation. There also might be one possible saving grace worth mentioning. If protocols and mechanisms to separate the locator and identifier become wide spread, then I think true end-node peer-to-peer communications should return to being commonly available. Apologies for the late comments, I've only recently been thinking a bit more about "global identities" after seeing SCTP behavior in more detail as well as a IPv6 sip client incorrectly picking a ULA address instead of a global address for an incoming media stream. Best regards, Mark. (Please CC me, I'm not subscribed. Thanks.) _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf