[ippm] IPPM Metric Registry Concept of Roles

[Heitor Ganzeli <[e-mail]>]

**

*Hello IPPM WG.*

*

At NIC.br we are developing a measurement system based on the LMAP
framework. Metrics (mainly private ones) are defined following the
proposed IPPM metric registry standard. During  this effort we
identified some doubts regarding the concept of roles in the metric
registry:


draft-ietf-ippm-metric-registry-17 states at 7.3.6


“7.3.6.  Role


  In some method of measurements, there may be several roles defined

  e.g. on a one-way packet delay active measurement, there is one

  measurement agent that generates the packets and the other one that

  receives the packets.  This column contains the name of the role for

  this particular entry.  In the previous example, there should be two

  entries in the registry, one for each role, so that when a

  measurement agent is instructed to perform the one way delay source

  metric know that it is supposed to generate packets.  The values for

  this field are defined in the reference method of measurement.”


Regarding a) an interest to avoid proliferation of metrics and b)
efficient use of the LMAP Framework (announcement of capabilities,
scheduling of tasks and reporting of results), shouldn't it be enough
and preferred to keep a single metric definition that can be referenced
with one of multiple possible roles? For example, an LMAP measurement
agent could announce the capability to execute a task producing the OWPD
metric, acting either as a client or a server. When scheduling a task
the LMAP controller would reference that OWPD metric and pin the role to
a specific value (ex: client). And when reporting measurement results
that same role would be reported together with the metric URN.


It seems the above use cases are solved with a single metric that allows
multiple roles. Regarding the metric registry, this perspective
interprets the "role" column as a enumeration of all roles applicable to
this metric, instead of indicating a single mandatory role.


Reinforcing this point of view, the draft-ietf-ippm-initial-registry-09
seem to list all possible roles when describing metrics. Items 4.3.6,
6.3.6, 7.3.6, 8.3.6, 9.3.6. But we do not have any concrete reference on
how the final LMAP report would be when reporting data for these metrics.


Could you please comment on the real motivation behind the current
draft's choice of creating multiple similar metrics with a single role
each? and if this part of the draft is open for discussions and
improvements?


Thanks in advance,

*

-- 
NIC.br | Heitor Ganzeli
Analista de Projetos/Projects Analyst
Centro de Estudos e Pesquisas em Tecnologias de Redes e Operações
(Ceptro.br)
[phone]R.: 4077
INOC 22548*HSG
www.nic.br <http://nic.br>