Subject: Re: [Roll] review of draft-ietf-roll-applicability-ami

From: "Jetcheva, Jorjeta" <[email-masked]>
Date: Wed, 19 Oct 2011 17:10:51 -0700

Hello Jari,

Thank you for the comments on the first version of the RPL AMI Applicability draft.  We have since published two more iterations and wanted to check in with you to make sure that we have addressed your concerns.  We look forward to your feedback.

Thanks, Jorjeta 

Jorjeta Jetcheva, Ph.D.
Strategic Industry Standards and Architecture
Office of the CTO
Mobile: +1.408.688.1428
Knowledge to Shape Your Future

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Jari Arkko
Sent: Friday, July 29, 2011 6:47 AM
To: [email-masked]
Subject: [Roll] review of draft-ietf-roll-applicability-ami

I have reviewed this document, and had some comments:

First off, I was one of the IESG members who have been asking for the 
ROLL working group to produce applicability statement(s) about RPL. 
Thank you for working on this! However, I think we are still not quite 
there. What at least I was asking for was more about experience, 
measurements, and analysis about how well RPL works in various types of 
networks. The current document is more descriptive (talks about the RPL 
design goals, for instance) and contains some profiling. While those 
parts are very useful as well, I feel that the core part of the 
contribution that this applicability statement should be making is 
missing. Perhaps the working should make an open call for the 
experience/measurements/analysis that is needed. Some may already exist, 
I'm sure.

Some additional more detailed comments:

The gas and water metering part discusses cases where the meters can or 
can not rely on the networks that electricity measurement devices have 
created. I think this description is not quite right. My experience is 
that gas and water meters tend to exist in places with power easily 
available. In Finland, for instance, water/heat pipe meters have been a 
standard for new homes dating back at least 2004, and they all run from 
mains power. So I think power will be available, and the ability to use 
another measuring network is kind of a secondary issue (and reuse of 
other networks may be more about administrative borders than about 
technology anyway).

Both the electricity and gas/water sections appear to take it almost for 
granted that multi-hop routing is necessary in these applications. 
That's certainly one way of building the networks, and the reason for 
the existence of this working group. But I would have expected that an 
applicability statement talked about the situations where this works 
best versus situations where some other solutions might work better. I 
see a lot of one-hop commercial deployment in this space, for instance, 
the metering systems in Finland are cellular-based. Is there something 
that you could say about when the different approaches are best 
applicable? Or is that purely a business issue, i.e., both work well and 
the only question is equipment/provider cost?

> As a result, all smart metering traffic
> typically goes through the LBRs, with the vast majority of traffic
> flowing from smart meter devices to the head-end servers, i.e., in a
> Multipoint-to-Point (MP2P) fashion.
>   

I'm not so sure about this. Pure metering implementations may have 
initiation on either side of the connection, and a request is likely to 
be a small packet but so are responses. As you note yourself later, 
there are firmware updates and other extraneous traffic cases that may 
balance the small response - slightly bigger response equation. In any 
case, its pretty useless of for me or you to guess -- but I'm guessing 
some actual operators have real data about the traffic mix and 
directionality. Can that be cited?

Jari

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