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@xxxxxxxx http://www.ietf.org/mailman/listinfo/ietf