I am not sure you got Jonathan's idea. Running protocols on top of UDP does not mean that you don't have congestion control. Joel M. Halpern wrote: > I would disagree about "no drawback." > The constraints are: > don't invent new transports > have congestion control > > and, for an important part of the traffic, do not have retransmission or > significant transmission delay (i.e. perform congestion control by > dropping packets.) > > Now, we have SCTP modes and DCCP which can address those needs over IP. > We do not have a defined protocol that runs over UDP that meets those > constraints. > We could just use UDP. But the congestion sensitivity aspect was > actually an important part of the work. > And the scoping (very near, near, or anywhere) was defined in the > negotiation with the IESG to give us bounds on the work and a framework > for making these sorts of decisions. > > So ignoring the bounds would be quite inappropriate. And the problem is > not solvable within the waist you have defined. > Which leaves us with either getting the work done, using IP and suitable > transports, or extending a very long process much longer. > > Not a good choice. > > Yours, > Joel > > Jonathan Rosenberg wrote: > >> Well, if history is any guide, eventually people will in fact want to >> run this from someplace a little farther away, and then you're in big >> trouble. So, I think the advice remains the same. There is no drawback >> to having it over UDP to start with - it works when there are no NAT, >> and it can work when there are NAT. >> >> -Jonathan R. >> >> Joel M. Halpern wrote: >> >>> However, I would really like to reinforce the point from another note. >>> There are quite a few contexts where the ability to run a sensible >>> transport directly over IP is indeed very useful. For example, the >>> ForCES working group scope is limited (by chart) to the case where the >>> control element is near the forwarding element. I am not worried >>> about there being a NAT between those. So SCTP or DCCP over IP is >>> very relevant. >>> >>> Yours, >>> Joel M. Halpern >>> >>> >>> Jonathan Rosenberg wrote: >>> >>>> I wrote this because of a discussion that happened during behave at >>>> the last IETF meeting in Vancouver. There was a presentation in the >>>> behave working group on NAT ALG for SCTP - when run natively over IP >>>> - and I found the entire conversation surreal. The entire problem >>>> would have been moot if SCTP had been designed to run over UDP and >>>> not IP. >>>> >>>> So apparently its not obvious to everyone that you cannot design >>>> protocols natively ontop of IP. >>>> >>>> -Jonathan R. >>>> >>> _______________________________________________ >>> Ietf mailing list >>> Ietf@xxxxxxxx >>> http://www.ietf.org/mailman/listinfo/ietf >>> >>> > _______________________________________________ > Ietf mailing list > Ietf@xxxxxxxx > http://www.ietf.org/mailman/listinfo/ietf > _______________________________________________ Ietf@xxxxxxxx http://www.ietf.org/mailman/listinfo/ietf