> 2020/01/27 午前11:59、Lou Berger <lberger@xxxxxxxx>のメール: > > okay, will leave it - Sounds good — > but we generally don't provide the motivation for every tradeoff / design decision in IETF standards. > though this is not what was asked :-) RFC 4385 says: To provide consistency between the designs of different types of PW, it SHOULD also use the following preferred format: So explaining why not following a SHOULD from the relevant PS seems appropriate. I agree, it would be counterproductive to provide the motivation for every tradeoff or design decision made. Please do not. The CW format, though, was asked a couple times. Carlos. > Lou > > On 1/27/2020 10:08 AM, Carlos Pignataro (cpignata) wrote: >> Hi, Lou, >> >>> 2020/01/27 午前9:41、Lou Berger <lberger@xxxxxxxx>のメール: >>> >>> Hi, >>> >>> Balázs thank you for the clarification -- see below for one comment. >>> >>> On 1/10/2020 8:56 AM, Balázs Varga A wrote: >>>> Yes, but why not the Preferred CW? >>>> >>>> <Balazs>/<Stewart> Sum of mailing + proposed fixing: >>>> The PCW only supports a 16bit sequence number and it has the skip zero auto-signaling of active S/N feature. >>>> This was a problem for DetNet because: >>>> - We were worried about S/N rollover frequency in some applications and so we wanted the option of a larger S/N. >>>> - We wanted to have the option to propagate the S/N from the payload to the transport to simplify the implementation >>>> in some cases. These applications have a non-skip zero S/N. Skip zero is an irritation to implement and we should probably >>>> have signaled in in PWs. >>>> As you note in is only a preferred design for PWs, DetNet is not constrained by that and there were good reasons to adopt >>>> this alternate approach. >>>> We assume to fix this with adding above information to the text. >>>> NEW text to be added in section 4.2.1: >>>> "This format of the d-CW was created in order (1) to allow larger S/N space to >>>> avoid S/N rollover frequency in some applications and (2) to allow non-skip >>>> zero S/N what simplifies implementation." >>> While I completely agree with the rational and validity of the good question, I don't think such motivation belongs in the document. We generally don't document every design decision in a specification. I don't feel strongly about this so if others do, I'll defer to their opinion... >>> >>> Balázs, Carlos, Do you think it should stay? >>> >> I have no strong feelings either way, but I believe if this is a departure from a “preferred” format from a BCP, then a one-liner explanation would not hurt. I’d leave this one in. >> >> Thanks, >> >> Carlos. >> >>> Thanks, >>> >>> Lou (as contributor) >>> -- last-call mailing list last-call@xxxxxxxx https://www.ietf.org/mailman/listinfo/last-call
