Re: [netmod] WG Last Call: draft-ietf-netmod-sub-intf-vlan-model-05

Martin Bjorklund <mbj@tail-f.com> Thu, 22 August 2019 20:14 UTC

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Subject: Re: [netmod] WG Last Call: draft-ietf-netmod-sub-intf-vlan-model-05
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Hi,

Here is my (late) review of draft-ietf-netmod-sub-intf-vlan-model-05.

o  1

  The YANG module names are not correct; they are listed as:

      if-l3-vlan.yang - Defines the model for basic classification of
      VLAN tagged traffic to L3 transport services

      flexible-encapsulation.yang - Defines the model for flexible
      classification of Ethernet/VLAN traffic to L2 transport services

   Should be "ietf-if-l3-vlan" and "ietf-flexible-encapsulation".

   Or "ietf-if-l3-vlan" and "ietf-if-flexible-encapsulation".

   But I also wonder if these names should somehow be changed.  What
   is a "l3-vlan"?  And "flexible-encapsulation" sound a bit too
   generic.


o  1.1

  The text says:

   Sub-interface: A sub-interface is a small augmentation of a regular
   interface in the standard YANG module for Interface Management that
   represents a subset of the traffic handled by its parent interface.

  I think the augmentation is the YANG-realization of a sub-interface,
  but it is not what a sub-interface is.  Also, this definition is
  mis-leading; it doesn't mention that a sub-interface has its own
  interface type and is represented as one separate entry in the
  interface list.  I think it is better to import this term from
  draft-ietf-netmod-intf-ext-yang (section 3.6)

o  3

  The text says:

   The L3 Interface VLAN model provides appropriate leaves for
   termination of an 802.1Q VLAN tagged segment to a sub-interface based
   L3 service.

  There is a comment in the YANG model that says the same thing.

  But the YANG model itself augments not only to sub-interface-based
  interface, but also to ethernet-like interfaces.


o  YANG modules

  Both modules lack the IETF Trust Copyright statement.

  We don't list WG Chairs anymore.

  The revision statements should be on the form: "RFC XXXX: <title>"

  Many descriptions are full sentences w/o the ending ".".

  The modules should be indented properly; a starting point can be
  pyang -f yang --yang-line-length 69


o  ietf-if-l3-vlan

  There is a comment:

    /*
     * Matches a single VLAN Id, or a pair of VLAN Ids to classify
     * traffic into an L3 service.
     */

  This should be moved into a description clause.

o  ietf-if-l3-vlan / container dot1q-vlan

  The must statement has:

     count(../../if-cmn:forwarding-mode) = 0

  This can be changed to not(../../if-cmn:forwarding-mode) which is
  more direct imo.

  The must statement's description statement seems to be a
  copy-and-paste error.


o  ietf-if-l3-vlan / container dot1q-vlan

  The descriptions talk about "matching frames" and "classifying
  traffic", but it is not described anywhere how the matching and
  classifying is used.

  (also applies to ietf-flexible-encapsulation)


o  ietf-if-l3-vlan / outer-tag / second-tag

  These names are a bit inconsistent.  The description describes them
  as "outermost tag" and "second outermost tag".  Perhaps use these
  names instead?

  (same names are found in ietf-flexible-encapsulation)



o  ietf-flexible-encapsulation / all features

  The features are described as:

      "This feature indicates whether the network element supports
        specifying flexible rewrite operations";

  Should this be s/whether/that ?


o  ietf-flexible-encapsulation

  There is some descriptive text in comments that should be moved to
  description statements.


o  ietf-flexible-encapsulation

  The descriptions for pop/push are a bit terse.  It seems to assume
  that readers already know what this (from somewhere) is so it
  doesn't need to be described.  If this is intended, perhaps add a
  reference to where this is described.



/martin