Re: [Roll] Ralph's DISCUSS on MRHOF spec
Philip Levis <pal@cs.stanford.edu> Fri, 08 June 2012 22:35 UTC
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Cc: Haberman Brian <brian@innovationslab.net>, roll <roll@ietf.org>, Stiemerling Martin <mstiemerling@googlemail.com>, Michael Richardson <mcr@sandelman.ca>
Subject: Re: [Roll] Ralph's DISCUSS on MRHOF spec
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On Jun 7, 2012, at 2:49 PM, Pascal Thubert (pthubert) wrote: > > [Pascal] I agree with Ralph here. I fail to be convinced that there will an explosion of OCPs if we fail to factorize the metrics. But I see how the device implementation can be simplified if the OCP says it all. Also, we do not want to force a device that implements MRHOF to have to implement all metrics in the I-D. Conversely, say we extend MrHof to other metrics with further work, wouldn't it become OCP 2 anyway? I wouldn't mind blocking OCP 1..9 for current and future MrHof metric variations. Well, here was your argument for it: Begin forwarded message: > From: "Pascal Thubert (pthubert)" <pthubert@cisco.com> > Subject: RE: rank and metric in DIOs > Date: November 6, 2009 12:52:54 AM PST > To: "Jonathan Hui" <jhui@archrock.com>, "Richard Kelsey" <richard.kelsey@ember.com> > Cc: <rpl-authors@external.cisco.com> > > Hi Jonathan: > > I do not think we need to enforce anything. The gear box protects the > future. I think we must leave the core spec abstract on that. And since > the burden is on the OCP anyway, what's the point? > > OTOH, we can design an OCP / metric where the metric has the properties > that is proposed here. In that case, the OCP should be simpler. OCP zero > is a bit like that if you look at it :) Maybe our disagreement is only > what is in the base spec (the generic thing) and what goes in a specific > instantiation (the OCP). > > I can wholeheartedly accept Richard's way of start simple and solid, and > then build over it if that's how more people can catch up with our work > for both understanding and implementation. As a next step for an OCP>0, > it is certainly a good thing to do. I'd support that, even more gladly > if we base it on ETX. > > Personally I think that this proposal yields limitations that will soon > appear inacceptable for a number of use cases where you have more > metrics, not necessarily incremental, fast varying, and logic to wrap > that up. So we MUST NOT make it generic. Some of those metrics you need > to propagate, but you do not want to change the rank and restart > trickle. > > I listed the properties of the rank several times already. Its stability > (long time constant is only one of those properties). > > A list (probably incomplete) of the differences: > > - its type: it is a scalar > - its function: it is a relative coordinate, not a cost or a distance to > root. > - its granularity: it is coarse grained to enable siblings > - its range with a short infinite > - its properties: rank is strictly monotonic, and increments from parent > rank + OCP stuff, not like the metrics themselves increment or > propagate. How would you play with throughput or jitter? > - universal and very abstract: we can always default to OCP0. I have > uses cases where I could actually do that successfully, like cars in a > parking lot. > > I think that the OCP job to turn its knowledge of the requirements, the > environment and the ranks of parents into a rank cannot be generalized. > Leaving that operation out of RPL base spec is actually making it > simpler. > > I'd be glad to add some words in RPL base spec on those rank properties > though... Phil
- [Roll] Ralph's DISCUSS on MRHOF spec Mukul Goyal
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Michael Richardson
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Mukul Goyal
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Philip Levis
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Pascal Thubert (pthubert)
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Omprakash Gnawali
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Philip Levis
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Mukul Goyal
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Mukul Goyal
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Mukul Goyal
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Mukul Goyal
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Michael Richardson
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Philip Levis
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Michael Richardson
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Pascal Thubert (pthubert)
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Pascal Thubert (pthubert)
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Philip Levis
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Philip Levis
- Re: [Roll] Ralph's DISCUSS on MRHOF spec JP Vasseur
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Michael Richardson
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Brian Haberman
- [Roll] Enhanced RPL functionality on J-Sim platfo… Panos Trakadas
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Don Sturek
- Re: [Roll] Enhanced RPL functionality on J-Sim pl… Ulrich Herberg
- [Roll] Σχετ: Enhanced RPL functionality on J-Sim … Panos Trakadas
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Omprakash Gnawali
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Panos Trakadas
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Omprakash Gnawali
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Mukul Goyal
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Omprakash Gnawali
- Re: [Roll] Ralph's DISCUSS on MRHOF spec Ralph Droms