Summary

  • draft-ietf-netmod-yang-ver-selection-00 proposed choosing a named schema-set at NETCONF session start or through a RESTCONF schema-specific path; the server retained control over what could be selected and which combinations could coexist.
  • Acceptance of that view proves neither that another client sees equivalent semantics nor that a write was authorized, isolated, committed, applied to operational state, forwarded, or produced the intended business result.

A controller opens two sessions to the same device. One negotiates the current schema. The other asks for an older schema that keeps a legacy client alive. Both receive syntactically successful replies. It is tempting to treat the two green sessions as interchangeable windows onto one machine. Revision 00 makes the opposite lesson available: the window is part of the evidence.

The proposal defined a schema-set as a named collection of datastore schemas. Each datastore schema was a union of compatible YANG packages, carrying module revisions, enabled features and deviations. Servers, not clients, would decide which schema-sets existed, which were selectable, and which could be used at the same time. Some sets could appear automatically; others might require configuration. A server could permit different views concurrently, or permit only one global selection and disconnect sessions using the old default when it changed.

NETCONF selection was fixed during the capability exchange at session start. The client supplied an ordered list; the first item also advertised by the server won. No intersection ended the session, while a client that did not ask used the default. RESTCONF used a schema-specific root path, so the selection belonged to the request path rather than a durable client identity. In either case, an accepted name located an interpretation context. It was not a certificate of equivalence.

That distinction matters because revision 00 also allowed a normally writable datastore such as running to be exposed as read-only under a particular schema-set. A successful read can therefore coexist with a deliberate inability to write. Even where writes are exposed, RFC 8341 access control still decides whether the authenticated principal may invoke the operation and touch the requested nodes. RFC 6241 then supplies separate protocol and datastore procedures. An <ok> response is not a packet trace, a FIB inspection, or proof that another client interpreted the same underlying configuration identically.

RFC 8525 adds a stronger inventory receipt by identifying datastore schemas, module sets, revisions, features and deviations. It does not turn a server declaration into a universal digest, and RFC 8342 keeps intended and operational state distinct.

The defensible chain therefore records server identity and time; advertised selectable sets and default; the exact selected name; the package and module closure; feature and deviation state; YANG Library snapshot; authenticated identity and NACM decision; transaction and concurrency history; pre/post datastore fingerprints; rollback result; intended and operational observations; forwarding evidence; and the bounded service outcome.

The status of the proposal is equally bounded. Revision 00 is dated 17 March 2020 and said it would expire on 18 September 2020. Datatracker now labels it an Expired Internet-Draft, Expired & archived, WG Document, and IESG Expired; its structured Intended RFC status is empty. The draft header said Intended status: Standards Track, but that was an authorial target, not approval. Datatracker also preserves a six-error, zero-warning YANG validation run. Those errors describe one 2020 tool and dependency closure; they do not prove either implementation failure or operational adoption.

Later work on YANG packages, module versioning, requirements and semantic versioning remains active in newer revisions. That subsequent activity does not revive schema-selection revision 00 or show that its protocol extensions were deployed. It merely confirms that versioned schema composition and client selection are different problems.

Sources

Primary record: revision 00, current status, and history. Protocol and evidence boundaries: RFC 6241, RFC 7950, RFC 8040, RFC 8341, RFC 8342, RFC 8525, and RFC 8526. Analytical framing: Minimum Initial Specification, Reality Layers, and Running-Code Primacy. Dependency and successor record: YANG 1.1, packages revision 03, module versioning revision 01, versioning requirements revision 02, semantic versioning revision 01, instance-file format revision 08, and the current Datatracker records for packages, module versioning, versioning requirements, and semantic versioning.