Some other points: On 7/26/2016 12:22 PM, Dino Farinacci wrote: > Now, let’s think about this. Why waste 4-bits or a byte for every single > packet when the UDP port number can be your version number. That UDP port > number has to be in every single packet anyways. > > Why keep the port number the same and change the version number when the same > cost of product change will occur. To save UDP port numbers? > > What if people wanted to filter v1 versus v2, doing it with a UDP port number > is a simpler and already deployed way to differentiate services. Now those > middle boxes have to look even deeper into the header?
Alternately, changing the port number then disables your protocol on all default-off configurations until it's opened up, which means V1 works but V2 doesn't. That can be very difficult to debug and track. In a nutshell, one of the reasons we're on a good track with the port number space is our conservative preservation. That includes requiring new assignments to support in-band versioning. The issue is "tragedy of the commons" - the cost of doing this "just for you" is low, but the cost to the community if everyone has permission *has already been deemed* too high. Finally, while I appreciate some of these considerations, they appear to be your opinion of the key aspects of IETF protocol design. They are not consistent with IETF BCPs, nor are they agreed as the best way to develop protocols that are useful *not only now* but in the future as well. Joe _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
