Liaison statement
LS/r IETF CCAMP work on YANG Alarm Module Submission (reply to IETF-LS16 )

ITU-T Study Group 15 thanks IETF CCAMP WG for informing us about the adoption
of a WG document https://tools.ietf.org/html/draft-ietf-ccamp-alarm-module-00
on “YANG Alarm Module” and requesting review on the module.

ITU-T Study Group 15 has been working, with collaboration with the ONF OIMT
Group, on a Core Information Model in Recommendation G.7711 (ONF TR-512). The
Core IM is neutral to any transport technology and is specified in UML, which
is neutral to any management/control interface protocol. The Core IM can be
pruned/refactored to provide a purpose-specific IM and translated into YANG
code by automated tooling (xmi2yang). The OAM functionality, including Fault
Management (FM) and Performance Monitoring (PM) is an area being modelled in
G.7711 (ONF TR-512).

Regarding the alarm management, we would like to see the FM and PM modelling
based on the same architecture, and to harmonize with the requirements in
Recommendation G.7710. The YANG module should also allow transport technology
specific augmentations.

Regarding the scope of the YANG Alarm Module, the draft should explicitly state
that the modeling of how transport resource alarms are raised and cleared by
the underlying transport instrumentation is out of the scope of this draft.
Specifically, the modelling of defect detection, defect coordination into fault
cause, consequent action, persistency verification declaring fault cause as
failure, and raising failure as alarm and its subsequent clearing should belong
to the SDO/group that owns the transport technology.

The alarm YANG draft adopts the X.733 alarm severities, but doesn’t support the
function of alarm severity assignment (i.e., configuring the severity of an
alarm type of a resource), i.e., the feature of the Alarm Severity Assignment
Profile (ASAP) object of M.3160/M.3100 is not supported by the draft. Is this
intended to be out of the scope of the alarm YANG draft?

For alarm reporting control, the alarm YANG draft supports only the simple
alarm shelf function. It doesn’t support the rich features of the Alarm
Reporting Control (ARC) function of M.3160/M.3100, which is required by G.7710.

We support the clear separation of resource alarm life-cycle from the operator
and administrative life-cycle of an alarm.

Listed below are specific comments from our review of the YANG Alarm Module

1.   Section 4.2, paragraphs 5 & 6 discuss unknow alarm type at design time and
dynamic addition of alarm types using string. Please note that the Spec Model
approach of the Core Information Model (ITU-T Recommendation G.7711 Annex G)
(also in ONF TR-512.7) provides a generic formal way to allow run time
enhancement/decoration.

2.   Section 4.4, first paragraph, second last sentence: Add “and alarm type
qualifier” so that the sentence becomes “This means that alarm notifications
for the same resource, same alarm type and same alarm type qualifier are
matched to update the same alarm instance.”

3.   Section 4.5: What is the relationship (dependency) among “alarm
clearance”, “alarm closing”, and “alarm deleting”. Will administrative deleting
automatically results in operator closing? Need more clarification among the
three types of alarm life-cycle. Otherwise will cause inconsistent handling of
alarm among different systems.

4.   Section 4.5.1, first paragraph, second line: Editorial error: “change
severity” occurs twice.

We appreciate again for the chance to exchange information. We would like take
this opportunity to inform IETF that we are currently working on a new draft
Recommendation G.media-mgmt that describes the requirement and information &
data model for transport media management.