> On Apr 14, 2023, at 04:39, Martin Björklund <mbj+i...@4668.se> wrote: > > Hi, > > I am quite confused after reading this thread, so I had to go back to > this first message: > > "Jason Sterne (Nokia)" <jason.ste...@nokia.com> wrote: >> Hi Jeff, >> >> One topic that came up during the IETF 116 NETMOD meeting was >> backwards compatibility. >> >>> From what I understand, a leaf (e.g. unknown-flags) that uses the >>> unknown-bits typedef would never change its definition in YANG. It >>> would always be defined as unknown-bits with all 64 bit definitions >>> even as more and more bits become "known". *But* the system would >>> suddenly stop reporting bit-0, then bit-1 in that unknown-flags leaf >>> as those bits become known. >> >> Strictly speaking, that should probably be considered an NBC change > > Nothing has changed in the data model, so there is no way to mark the > _data model_ as NBC. > > The server follows the data model, and reports which bits it doesn't > understand. With software updates, this may change over time. This > is simply the semantics of this state leaf.
I agree. Removing the definition of the unknown bit in the second leaf for unknown bits is not backward compatible but that isn’t being proposed. Also, one can define a new bit in an unused position in an augmentation - correct? Thanks, Acee > > > /martin > > _______________________________________________ > netmod mailing list > netmod@ietf.org > https://www.ietf.org/mailman/listinfo/netmod _______________________________________________ netmod mailing list netmod@ietf.org https://www.ietf.org/mailman/listinfo/netmod
