Re: [netmod] Changing an identity base

["Hartley, Jeff" <[e-mail]>]

Yes, bar's relationship to base identity foo is Backward-Compatible in both cases.  We've used the "multiple base" methodology in some of the recently-released BBF models, as one example.

The main potential concern is that (A) is a bit awkward (in my opinion), and whether your YANG tooling will handle that.  (B) is also likely easier to read for your end-users.  (YMMV).

Thanks;
-Jeff


From: netmod <[e-mail]> On Behalf Of Italo Busi
Sent: Friday, January 27, 2023 11:55 AM
To: [e-mail]
Subject: [netmod] Changing an identity base

According to section 11 of RFC7950, the following change is considered BC: o A "base" statement may be added to an "identity" statement. Since, as explained in section 7.18.2 of RF
External (italo.busi=[e-mail]<mailto:italo.busi=[e-mail]>)
  Report This Email<https://protection.inkyphishfence.com/report?id=Y29tbXNjb3BlL2plZmYuaGFydGxleUBjb21tc2NvcGUuY29tLzA0Njc2ZWNlMmFlNGM3OTQzOTFhMzZlNzNjOWQ5ZmY3LzE2NzQ4Mzg1MDEuMTM=#key=4a1d6108a6ce092fcc6b62878ef6f9d0>  FAQ<https://www.inky.com/banner-faq>  Protection by INKY<https://www.inky.com/protection-by-inky>

According to section 11 of RFC7950, the following change is considered BC:

   o  A "base" statement may be added to an "identity" statement.

Since, as explained in section 7.18.2 of RFC7950, the derivation of identities is transitive, my understanding is that replacing a "base" statement with new  "base" statement which is derived from the previous one is also a BC change.

Considering the example below, the NEW (A) change is BC according to section 11 of RFC7950. However, NEW (B) is equivalent to NEW (A), since the new baz is derived from foo, and therefore it is also a BC change.

Is my understanding correct?

Thanks, Italo

OLD

identity foo {}

identity bar {
  base foo;
}

NEW (A)

identity foo {}

identity baz {
  base foo
}

identity bar {
  base foo;
  base baz;
}

NEW (B)

identity foo {}

identity baz {
  base foo
}

identity bar {
  base baz;
}