I remember that what Remi said during the meeting, is that 4rd-u is a brand-new transport protocol which doesn't need to follow rfc6145 translation spec. If it is true, 4rd-u doesn't need to take care checksum consistency of any kind of L4 protocols. On the other word, 4rd-u can support transparency of original packet so not only the CNP, but also checksum recalculation are not required.
cheers, --satoru On 2012/03/28, at 11:02, Simon Perreault wrote: > On 03/28/12 10:48, Satoru Matsushima wrote: >>> On the contrary, there is a big difference. The difference is that you are >>> only concerned with L3. L4 can change: UDP, TCP, ICMP, STCP, DCCP, etc, >>> etc, etc. You need a lot of code to handle all existing transport >>> protocols, and you still can't handle future protocols that people might >>> develop. >>> >>> Checksum neutrality is a *big* advantage. >> >> Cool. How many protocols we should support for just a *transition* mechanism? > > The way I see it, IPv4-over-IPv6 (e.g. 4rd) has potential to be used for a > longer time than IPv6-over-IPv4 (e.g. 6rd). Operators will need to keep > providing clients with residual IPv4 for a potentially loooooooooooong time. > So we need to be really careful to get this right, because we'll be stuck > with what we design for a long time. > > So you have two options: > > a) checksum neutrality > - no code specific to each transport prototol > - supports all current and future transport protocols > b) checksum non-neutrality > - additional code necessary for each transport protocol > - limited set of supported transport protocols > > Less code, more transport protocols. I think the choice is easy. > > There's a reason NPTv6 and NAT64 chose checksum neutrality... > > Simon > -- > DTN made easy, lean, and smart --> http://postellation.viagenie.ca > NAT64/DNS64 open-source --> http://ecdysis.viagenie.ca > STUN/TURN server --> http://numb.viagenie.ca _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
