Subject: Re: [Roll] Unique destinations and the protocol survey draft

From: Philip Levis <[email-masked]>
Date: Fri, 21 Nov 2008 10:54:44 -0800

On Nov 21, 2008, at 2:58 AM, <giyyarpuram.madhusudan@orange- 
ftgroup.com> <[email-masked]> wrote:

>> hat make sense?
>> Phil
> Phil,
> I agree that apps with small D should not have to pay the price for  
> big
> D apps.=20
> However there seems to be the supposition that the small D is the
> "general" case and the big D
> is the exception.

What text in the document leads you to that conclusion? I try to pick  
words very carefully. "Many" implies neither a majority nor a  
plurality[1]; trying to make broad claims over which apps will be more  
common than others would be a bit silly at this point. The point of  
that claim is that the "many" is large enough that putting our head in  
the sand and just assuming O(N) state is always OK is, well, *not* OK.

> Hence claims like O(D) scaling passes or O(D) route
> updates passes.
> It seems to me that the trend in "many" apps is towards more active
> contol as opposed to pure data
> collection. This has been true in AMR which is becoming more AMI.=20
> Also this is not a just a sensor/actuator ratio. Even for sensors that
> only send reports one may want
> to send configuration commands that change the frequency of  
> reporting or
> request frequent updates for a
> short period of time or change the threshold for events.

True. But the whole point of O(D) is that it subsumes this; if you  
need unicast communication to every node in the network; then D=N and  
so you can have O(N).

>
> However I would buy the argument that data collection traffic will be
> much higher than=20
> command/query/configure traffic. So perhaps it is a question of
> optimizing for data collection=20
> and shifting the burden for command traffic onto the originator  
> (such as
> source routing).

Well, there are a lot of reasons why source routing raises issues, in  
particular adaptation to the dynamicity typical to low-power wireless  
links.

Phil

[1] "John McCain received many votes this year;" "Many Americans  
believe it's time for change;" "Many households use NATs;" "Many  
websites do not work properly with IPv6."

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