Thanks for writing draft-phelan-dccp-natencap-00.txt. In it, I noticed: For DCCP-NAT, the function of the DCCP-RAW generic header field Checksum is performed by the UDP Checksum field.
If the UDP Checksum field in a received packet is invalid or has a value of 0, that packet MUST be ignored as per the invalid checksum procedures of DCCP-RAW (i.e., the options in the packet MUST NOT be processed). I found this curious. I would have designed it the other way, so that if the UDP checksum is 0, you could use DCCP's checksum or DCCP's partial checksum. In this way, you would get one of DCCP's additional advantages (partial checksum) when you are forced to encapsulate DCCP over UDP. (By the way, there is a discussion relevant to DCCP-over-UDP, and DCCP with NATs, on the main IETF list, starting at about http://www.ietf.org/mail-archive/web/ietf/current/msg50256.html, Subject "[Fwd: I-D Action:draft-rosenberg-internet-waist-hourglass-00.txt]".) -d
