Problem observed with a NETCONF device using RFC7950/YANG1.1 modules from  Broadband Forum, like YANG Module "bbf-l2-forwarding@2020-10-13.yang". This module contains submodules via include.  

Via apidoc/explorer via RESTCONF (rfc8040) ietf-yang-library:yang-library list is provided correctly by server and delivered by ODL.

During connect ODL is not loading the submodules of bbf-l2-forwarding@2020-10-13, using ietf-yang-library (cache-schema does not contains this modules)

ODL seems to use the "netconf-state xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring"" schemas to request during startup the YANG modules from device modules.

Versions:

• SDNC Version Istanbul 2.2.3 (Silicon SR1)
• ODL Versions: Aluminium SR3, Silicon SR1, Phosphosrus SR0+SR1

netconf-server:

• The server does not exposes the submodules into the list of netconf-state xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring" schemas.
• According to rfc8525/rfc7950 the YANG1.1 modules are not listed in hello message.
• Server is providing yang-library in hello
  • with rfc8525 content-id and not using module-set-id module-set-id

  • <capability>urn:ietf:params:netconf:capability:yang-library:1.1?revision=2019-01-04&amp;content-id=82</capability>

Problem: 

• Module "bbf-l2-forwarding@2020-10-13.yang" and all  YANG1.1 modules, using submodules are marked as unavailable.

Expected behavior

According to RFC7950 last paragraph of chapter 1.1. Summary of Changes from RFC 6020:
The following changes have been done to the NETCONF mapping:

o A server advertises support for YANG 1.1 modules by using
ietf-yang-library [
RFC7895
] instead of listing them as
capabilities in the <hello> message.
ODL should use the ietf-yang-library/RFC8525 function to load and process YANG1.1 module and submodule information.

Workarround

Force netconf-server to provide all schema information via ietf-netconf-monitoring schema list - including submodules.

SDNC Version: Istanbul 2.2.3 (Silicon SR1)

Observed with ODL Versions: Aluminium SR3, Silicon SR1, Phosphorus SR0+SR1