This time to IETF list; As I wrote: > The problem, however, is that the review comment are so > surprising that the result of SEMI workshop is very simply > proven (see below) to be "incorrect and incomplete". are there anyone who argue against the proof? To explain it less formally without the end to end argument, According to RFC3424 written by IAB: o Shipping NATs often contain Application Layer Gateways (ALGs) which attempt to be context-sensitive, depending on the source or destination port number. The behavior of the ALGs can be hard to anticipate and these behaviors have not always been documented. but, CFP of SEMI2015 says: Can common transport functionality and standardization help application developers to implement and deploy such approaches in today’s Internet? which means SEMI2015 has, quite seemingly, a prejudice to focus only on "common" and/or standardized, thus, well known, functionality of ALGs, ignoring undocumented ones. As such, it is obvious that such approach won't work for ALGs with undocumented functionality. Then, there is no point to have SEMI2015 only to harm the Internet community by having an IAB authorized workshop report containing wrong approaches. Still, one might argue that, with incremental approach by making the mechanisms more and more complicated, at some point, we might finally be able to make it complete and correct. Those who can enjoy the formalism of the end to end argument can recognize that the argument is the simple and straight forward proof that it is impossible. Masataka Ohta