On Mon, Jun 13, 2016 at 5:57 PM, Carles Gomez Montenegro <[email protected]> wrote: >> >>> A TCP window size of one segment follows the same rationale as the >>> default setting for NSTART in [RFC7252], leading to equivalent >>> operation when CoAP is used over TCP. >> >> IMHO, it does not matter because if the application has only a short >> message to send, the de facto effective cwnd will be ONE. > > I understand that what you point out may happen in many cases... However, > a device, in some cases, might want to send e.g. two (or more) packets > back to back to the same destination. In those, the window size of one > would make a difference. > > By the way, currently the phrasing in the draft is that a window size of > one 'MUST' be used. This keeps a behavior equivalent to that of CoAP for > confirmable messages in RFC 7252, and dramatically simplifies > implementations. However, I wonder if some more freedom should be offered, > and maybe the 'MUST' could become a 'SHOULD', at the expense of opening > the door to greater complexity... I personally tend to prefer the first > approach, but it would be great to receive more feedback on this!
Which way is better in this case, sending two and sleep, or sending one followed by another? Sometimes the former will be better for constrained nodes. > > >>>3.3. RTO estimation >>> challenges of CNNs, in contrast with the RFC 6298 RTO. Therefore, as >>> per this document, CoCoA RTO SHOULD be used in TCP over CNNs. >>> Alternatively, implementors MAY choose the RTO estimation algorithm >>> defined in RFC 6298. One of the two RTO algorithms MUST be >>> implemented. >> >> Is the RTO estimation algorithm link-specific? For example, I knew you >> have some work on CoCoA over GPRS. Is it always better than the >> competitor? > > These are crucial questions. In our work with CoCoA (e.g. [1]), we have used: Thanks a lot for the reference and clarification, a nice measurement paper indeed! Cheers, Zhen > > - GPRS/UMTS emulation > - GPRS testbed experiments > - IEEE 802.15.4 (with and without L2 reliability) simulation > - IEEE 802.15.4 testbed experiments > > > Carles > > [1] Here is our most mature paper on the topic: > https://www.researchgate.net/publication/297989374_CoAP_Congestion_Control_for_the_Internet_of_Things > > >> Cheers, >> Zhen > _______________________________________________ Lwip mailing list [email protected] https://www.ietf.org/mailman/listinfo/lwip
