Re: [Roll] Ralph's DISCUSS on MRHOF spec

Philip Levis <pal@cs.stanford.edu> Wed, 06 June 2012 14:42 UTC

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Subject: Re: [Roll] Ralph's DISCUSS on MRHOF spec
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Responses inline.

On Jun 4, 2012, at 9:31 AM, Ralph Droms wrote:

>> 
> 
> My question here is why a single objective function "MRHOF" is defined to use several different metrics.  My understanding is that any specific RPL instance will use one metric as its "selected metric" for MRHOF.  Another way to organize the objective functions would be to define a different OF number for each metric, binding the OF number to the selected metric.

This was a design decision made early in RPL. There were two options: OFs are metric-specific, or OFs can be general with respect to metrics. The design team concluded the second approach was better, as the former would lead to a possibly huge number of OFs that would be hard to manage.

Phil