Subject: [eman] Comments on Power Management Architecture

From: JinHyeock Choi <[email-masked]>
Date: Wed, 6 Oct 2010 15:05:44 +0900

Hi

Here are some comments.

1. Communication model
I wish the communication model between Power Monitor & NMS
(to which information would be ultimately reported, I assume).
is more clearly presented.

The power monitoring information is defined in detail
but it’s not clear
which entity report that information
to which entity through which mechanism.

For example I guess that

  Large time series of energy consumption values of a Power Monitor Child
  are reported by Power Monitor Parent to NMS though IPFIX (or Syslog)

but can’t be sure that’s right.

Though there are some related contents in 7. Fault Management,
I wish more clear statements & elaboration.

For more clear communication model,
it would help to add some paragraphs about

1) participating entities
    as defined in Nordman I-D .

    Participating entities are monitoring systems that receive
    information and networked devices that provide information on energy
    consumption and power state information concerning themselves or
    potentially also other devices.

BTW which entity is IP enabled?
Which entity understands IP to report to NMS (via SNMP)?
All Power Monitor or Power Monitor Parent?

2) monitoring model
    SNMP/ MIB or IPFIX
    as presented in [POWER-MON-REQ].

BTW [POWER-MON-REQ] propose to (in Sec 6) develop
a standard for pull-based power state monitoring
and push based one (with IPFIX or Syslog).
About which, this document won’t make any statement?

2. Power Monitor Parent & Child
There are some ambiguities regarding
Power Monitor Parent & Child relationship.

First it’s not clear which makes two entities
Power Monitor Parent & Power Monitor Child.

>From the document, I assume either
i) a Parent provides a Child power (as in PoE) or
ii) a Child reports power information to its Parent.

However, in 4.3, it’s written

        A Power Monitor Child can be fully dependent on the Power
        Monitor Parent (as in the case of Power Over Ethernet) or
        independent from the parent (such as a PC connected to a
        switch).

What makes a PC a child to a switch?
Just because it’s connected to the switch or
is it assumed that the PC report its power usage to the switch?

Also what if a Parent provides a Child a power
but the Parent neither monitor the Child’s power usage
nor the Child makes no report to the Parent?

In the above case,
The Parent plays no role in the Child’s Power Monitoring.

Here are some more questions.

1) Can a Child have more than one Parents?
For example a IP phone may get a power from PoE
but report its power usage to a building gateway.

2) Does Parent always report
the power information of its’ Child for its stead?
If so, to whom, NMS of it’s own Parent?

3) It’s written

     A Power Monitor cannot be at the same time a Power Monitor
     Parent and a Power Monitor Child.

But the above seems to contradict with
Figure 4 of Scenario 1 of [POWER-MON-MIB]
in which
SWITCH PORT is the CHILD of SWITCH and
the PARENT of IP PHONE at that same time.
Please clarify.

4) Which entity report to NMS with IP?
A Child can make its own report to NMS
or always a Parent should report for its stead?

Best Regards

JinHyeock Choi

---

From: john parello <[email-masked]>
Date: Fri, 15 Oct 2010 11:43:31 -0700

Hi JinHyeock,

Thanks for the feedback and review. We have made changes to help clarify 
some of your point and it will be posted to the list.

Please see inline for our thinking on the various points.

On 10/5/10 11:05 PM, JinHyeock Choi wrote:
> Hi
>
> Here are some comments.
>
> 1. Communication model
> I wish the communication model between Power Monitor&  NMS

[jparello] That's true however the assumption is that the communication 
between the NMS and POwer Monitors would be via SNMP. So the 
Architecture is a description of what we need that is then implemented 
via SNMP data model.

> but can’t be sure that’s right.

[jparello] The group has not put a requirement for IPFIX but that could 
be brought up the the WG meeting.

> I wish more clear statements&  elaboration.
>

[jparello] Yes I think we have this covered in the definition of Power 
Monitor itself.

> All Power Monitor or Power Monitor Parent?

[jparello] The assumption is that we are starting with SNMP first so a 
Parent power monitor would implement the mib and then and subtended 
devices that did not or could not implement SNMP would be aggregated to 
the Power Monitor parent.

> About which, this document won’t make any statement?

[jparello] See previous that IPFIX could be brought up as a WG item IMO.

> 2. Power Monitor Parent&  Child
> Power Monitor Parent&  Child relationship.
>
> Power Monitor Parent&  Power Monitor Child.
>

[jparello] We have added this in the next revision about to be posted.

> ii) a Child reports power information to its Parent.

[jparello] The parent may or may not provide power to the child. For 
instance a PoE switch would have PoE endpoints as children and in this 
case would clearly provide power to the child. In the case of a wireless 
controller the controller may be the parent of the wireless APs but they 
may draw power directly from a wall outlet.

> is it assumed that the PC report its power usage to the switch?
[jparello] Yes. The idea is that some device that is capable of 
communicating power usage could act as an aggregation point for other 
subtended devices. So a switch could be a parent for connected PCs. One 
could have one PC that is the parent and SNMP capable and other PCs that 
are not capable as children. The proposed architecture allows for one 
device that can communicate power information to an NMS can act as a 
parent or aggregation point for others that cannot communicate to the NMS.

> nor the Child makes no report to the Parent?

[jparello] In that case we envision the parent to at least provide the 
nameplate power characteristics of itself or even better of the 
children. The power usage data model allows the Power Monitor parent to 
describe how and to what accuracy the usage is reported. In this 
scenario it would be a poor participant but could still presumably 
report nameplate power.

> The Parent plays no role in the Child’s Power Monitoring.

[jparello] see above.

> but report its power usage to a building gateway.

[jparello] The parent is defines as the device that aggregates and 
provides reporting it may not be the source of the power. So we 
specifically don't want a device to report its power to two parents as 
that would cause double counting.

> If so, to whom, NMS of it’s own Parent?

[jparello] The parent may report the power usage on behalf of the child 
or may delegate it to the child and aggregate it to the NMS.

> the PARENT of IP PHONE at that same time.

[jparello] For SNMP the NMS would talk to each parent directly to get 
power information. Having a parent that is also a child of another 
parent would cause the devices to begin to "walk the network". As such 
we specified each parent as a disjoint tree of power reporting.

> or always a Parent should report for its stead?

[jparello] By definition the parent aggregates it.

Thanks so much!
John

---

From: Ted Ghose <[email-masked]>
Date: Sun, 17 Oct 2010 00:47:30 -0700

in line, look for [tg]

> All Power Monitor or Power Monitor Parent?
[tg] if entity is ip enable, it can report its own information. if the
entity is ip enable and do not have capability to monitor its own energy
usage, it should at least be capable of telling (automatically or by
configuration) who is monitoring its usage.

2) monitoring model
> About which, this document won’t make any statement?

[tg] ipfix is a better choice, I'd keep it open for discussion. ipfix is
more designed towards data collection for data mining.

> The Parent plays no role in the Child’s Power Monitoring.
[tg] model we should be looking for is:

* entity that are not capable of monitoring/manage its own power to align up
to a device who can do this for it, hence this device will be a child of the
device who control it.

> but report its power usage to a building gateway.

[tg] if someone providing the PoE power, it will be double counting to
measure it from building gateway. In this light we should have one and only
one parent.

> If so, to whom, NMS of it’s own Parent?
[tg] if and only if a child wish the parent to report or control its power.
We will always like to to make the end device to make the call.

> the PARENT of IP PHONE at that same time.
[tg] please read: monitoring of the device who is monitoring other devices
is orthogonal about its own consumption. Take the case of an electric meter
of a home. The meter may not be capable of measuring its own usage, but can
measure the power drawn by the home. Now the power drawn by the meter can be
monitored by someone else, hence the flexibility presented!

> or always a Parent should report for its stead?

[tg] in the light of all above cases, it depends. if a device is capable of
doing so, it will, else it can ask somebody else to manage it for him.

Best Regards

-tg-

>
> Best Regards
>
> JinHyeock Choi
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