On 2010-04-23 06:40, Rémi Després wrote: > Le 22 avr. 2010 à 19:31, Steven Blake a écrit : > >> On Thu, 22 Apr 2010 10:08:34 +0200, Rémi Després <remi.desp...@free.fr> >> wrote: >> >>> Le 21 avr. 2010 à 23:17, Brian E Carpenter a écrit : >>> >>>> On 2010-04-21 20:50, Rémi Després wrote: >>>>> Hi Brian, >>>>> >>>>> I wonder what you think of what I answered to James on another >>>>> discussion thread. >>>> I agree. I think that particular SHOULD in the RFC is an error. It >>>> "SHOULD" >>>> have said something like: >>>> >>>> "The source node MUST select new Flow Label values by a method that >>>> prevents unintended Flow Label value reuse." >>> Yes, that's more appropriate. >>> >>> Suggesting in addition that a 5-tuple hash can be an easy way to set >>> flow-label values, because it is stateless, would IMHO improve chances >> that >>> host really set them. >>> Wold you agree on this too? >> My reading of "The source node MUST select new Flow Label values by a >> method that prevents unintended Flow Label value reuse." would preclude use >> of a 5-tuple hash, which could result in coincidental selection of a flow >> label value already in-use by another flow. > > Well, "unintended" may be taken as permitting the hash (its intent of the > hash that two different 5-tuples give in general two different values, with > only statistically rare exceptions), but better words may also be proposed. > In any case, explicitly permitting the 5-tuple hash is IMHO desireble.
Yes. And if that produces identical hashes for two different 5-tuples, then the lawyer in me says that's "intended" so does not break the MUST. This needs to be carefully wordsmithed, but I think we are in agreement. Brian > > Regard, > RD > > >> Do we really want/need to specify a MUST here? What is wrong with >> low-probability, coincidental flow label reuse between flows with different >> source/destination address pairs, so long as the values are otherwise >> uniformly distributed and unpredictable? >> >> >> Regards, >> >> // Steve > > -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
