Early Review of draft-ietf-teas-yang-path-computation-11
review-ietf-teas-yang-path-computation-11-yangdoctors-early-bjorklund-2020-12-17-00

o  General

  The language is called "YANG", not "Yang".


o  1.2. Tree Diagram

  The text says:

    A simplified graphical representation of the data model is used in
    section 6.1 of this this document.  The meaning of the symbols in
    these diagrams is defined in [RFC8340].

  Tree diagrams are used also in chapter 5.  I suggest:

    Tree diagrams used in this document follow the notation defined in
    [RFC8340].


o  Tree diagrams in general

   You can use pyang -f tree --tree-line-length 68 ... in order to
   avoid long lines in the RFC.


o  6.1

  This section presents a fully expanded tree diagram of the module.
  Tree diagrams are mainly used to give an overview of a module's
  structure.  The tree diagram in this section spans 13 pages and is
  quite hard to read.

  I also note that a majority of the nodes in this tree diagram come
  from the expansion of groupings that aren't defined in this
  document.  Hence, I suggest that you might want to run:

    pyang -f tree --tree-line-length 68 \
      --tree-print-groupings --tree-no-expand-uses


o  There are a number of groupings that are used only once, and do not
   seem to be defined to be reused by other modules, e.g.,
   "requested-info", "requested-state", "svec-metrics-bounds" and more.

   If they are intended to be reused, it should be made clear in their
   description statements.  If not, I think they should be inlined and
   removed.


o  grouping svec-exclude

   This grouping has an ordered-by user list.  Why is this list user
   ordered?  If the order matters, it should be explained how it matters.

   Also, the index leaf has this description:

     "XRO subobject index"

   What is "XRO"?  Is this description sufficiently clear?


o  path-request

   In the path-request, there is construct for path-refs:

                   list primary-reverse-path-ref {
                     key index;
                     min-elements 1;
                     description
                       "The list of primary reverse paths that
                        reference this path as a candidate
                        secondary reverse path";
                     leaf index {
                       type uint32;
                       description
                         "The index used by the
                          primary-reverse-path-ref list";
                     }


  What is this index?  Is it only used as an arbitrary index, or
  something else?  If it is an arbitraty index, it should be explained
  in the descriptions.

  Also note that lists in rpc input don't need an index.


o  Validation

   The module fails YANG validation, but that is really due to errors
   in ietf-te@2020-07-12.yang.  Specifially, the leafref in the
   grouping "path-compute-info" must have prefixes in its path.
   Without prefixes, the path refers to nodes in the module that uses
   the grouping.  (same for other groupings in that module).


o  Layout

  I suggest you run the module through

    pyang -f yang --yang-canonical --yang-line-length 68

  in order to have the module indented and formatted consistently.

  This will make the RFC editor's job easier.
  


/martin