Hi,
"Jason Sterne (Nokia)" <[email protected]> wrote: > Hi Martin, > > If a "description" of a leaf (without a default statement) changes from this: > > "the absence of this leaf causes the protocol to stay administratively > down" > > to this: > > "the absence of this leaf causes the protocol to go administratively up" > > (with no other changes in the YANG) then IMO it *is* an NBC > change. The behavior described in a "description" field is > considered part of the model/API (I've seen many references & > examples of this over the years in NETMOD/NETCONF discussions). Absolutely. But that's not what we disuss in this case. In this case we have a leaf that shows "unknown bits", and neither the type nor the leaf (including descriptions) change during the upgrade. /martin > > Maybe it becomes more subtle if that behavior change isn't documented in the > "description" statement (I'd argue it is still NBC if the server changes that > behavior and they should be publishing a new revision of the YANG model/API), > but I was proposing that it should in this case. > > Jason > > > -----Original Message----- > > From: Martin Björklund <[email protected]> > > Sent: Friday, April 14, 2023 4:39 AM > > To: Jason Sterne (Nokia) <[email protected]> > > Cc: [email protected]; [email protected] > > Subject: Re: [netmod] Unknown bits - backwards compatibility > > > > > > CAUTION: This is an external email. Please be very careful when clicking > > links or > > opening attachments. See the URL nok.it/ext for additional information. > > > > > > > > Hi, > > > > I am quite confused after reading this thread, so I had to go back to > > this first message: > > > > "Jason Sterne (Nokia)" <[email protected]> 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. > > > > > > /martin _______________________________________________ netmod mailing list [email protected] https://www.ietf.org/mailman/listinfo/netmod
