Re: [Roll] knowing which multiple metrics matter: MRHOF related questions
Mukul Goyal <mukul@uwm.edu> Tue, 05 June 2012 08:55 UTC
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Date: Tue, 05 Jun 2012 03:55:36 -0500
From: Mukul Goyal <mukul@uwm.edu>
To: Ralph Droms <rdroms.ietf@gmail.com>
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Cc: roll <roll@ietf.org>, Stiemerling Martin <mstiemerling@googlemail.com>, Haberman Brian <brian@innovationslab.net>
Subject: Re: [Roll] knowing which multiple metrics matter: MRHOF related questions
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Hi Ralph ***************************************************************************** [MCR] > - do the nodes of a DODAG have to use the same metrics to pick a parent, > (and if so, how do they agree) > I think that they do not, so long as they use an algorithm (such as > MRHOF) which has certain properties. > [Mukul] Yes, the nodes in a DODAG have to use the same metrics. Otherwise, it is not possible for an OF to map the aggregated (from root till this node) values of the metrics to a rank. [Ralph2] "metrics" or "metric"? [Mukul2] "Metrics" if we are talking about OF in general. "Metric" if we are talking about MRHOF in particular. [Ralph2] Can different nodes use different metrics in a RPL instance that specifies MRHOF? I would think the answer is "no"; i.e., all nodes in a RPL instance MUST use the same metric as the "selected metric". [Mukul2] You are right. ********************************************************************************** [MCR] > - if we had multiple RPL instances in an LLN, using different metrics, > then we would have multiple RPL Instances and DODAGs. The different > set of metrics would not co-exist in the same RPL Instance. [Mukul] > Not sure what does the first sentence mean. About the second, different sets of metrics can certainly coexist in the same RPL instance. An RPL Instance is associated with a particular OF but different DODAGs in the RPL Instance can certainly use different routing metrics. [Ralph2] Perhaps I am confused. Do all the nodes in a single DODAG use the same metric while nodes in different DODAGs (in the same RPL instance) can use different metrics? I.e., for a RPL instance with tow DODAGs, all the nodes in DODAG1 use ETX while all the nodes in DODAG2 use hop count? [Mukul2] I thought so until Pascal told me today that this is not correct. The reason is that a node may want to jump from one DAG to another (e.g. if both DAGs provide connectivity to a particular prefix and the node will have a better rank in the other DAG). But, in order to allow a node to compare its rank in different DAGs, both OF and metrics in use should be same for both DAGs. Thanks Mukul > > ----- Original Message ----- > From: "Michael Richardson" <mcr+ietf@sandelman.ca> > To: "Pascal Thubert (pthubert)" <pthubert@cisco.com> > Cc: roll@ietf.org > Sent: Friday, May 25, 2012 2:29:49 PM > Subject: Re: [Roll] knowing which multiple metrics matter: MRHOF related questions > > >>>>>> "Pascal" == Pascal Thubert <(pthubert)" <pthubert@cisco.com>> writes: > Pascal> I think RPL does not want to take party there. The OF is a > Pascal> piece of logic to tie metrics and policies together. > > My question is: > > - do the nodes of a DODAG have to use the same metrics to pick a parent, > (and if so, how do they agree) > I think that they do not, so long as they use an algorithm (such as > MRHOF) which has certain properties. > > - if we had multiple RPL instances in an LLN, using different metrics, > then we would have multiple RPL Instances and DODAGs. The different > set of metrics would not co-exist in the same RPL Instance. > > > -- > Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works > IETF ROLL WG co-chair. http://datatracker.ietf.org/wg/roll/charter/ > > > _______________________________________________ > Roll mailing list > Roll@ietf.org > https://www.ietf.org/mailman/listinfo/roll > _______________________________________________ > Roll mailing list > Roll@ietf.org > https://www.ietf.org/mailman/listinfo/roll
- [Roll] knowing which multiple metrics matter: MRH… Michael Richardson
- Re: [Roll] knowing which multiple metrics matter:… Pascal Thubert (pthubert)
- Re: [Roll] knowing which multiple metrics matter:… JP Vasseur
- Re: [Roll] knowing which multiple metrics matter:… Michael Richardson
- Re: [Roll] knowing which multiple metrics matter:… Mukul Goyal
- Re: [Roll] knowing which multiple metrics matter:… Pascal Thubert (pthubert)
- Re: [Roll] knowing which multiple metrics matter:… Ralph Droms
- Re: [Roll] knowing which multiple metrics matter:… Omprakash Gnawali
- Re: [Roll] knowing which multiple metrics matter:… JP Vasseur
- Re: [Roll] knowing which multiple metrics matter:… Pascal Thubert (pthubert)
- Re: [Roll] knowing which multiple metrics matter:… Don Sturek
- Re: [Roll] knowing which multiple metrics matter:… Ralph Droms
- Re: [Roll] knowing which multiple metrics matter:… Ralph Droms
- Re: [Roll] knowing which multiple metrics matter:… Ralph Droms
- Re: [Roll] knowing which multiple metrics matter:… Mukul Goyal
- Re: [Roll] knowing which multiple metrics matter:… Pascal Thubert (pthubert)
- Re: [Roll] knowing which multiple metrics matter:… Mukul Goyal
- Re: [Roll] knowing which multiple metrics matter:… Pascal Thubert (pthubert)
- Re: [Roll] knowing which multiple metrics matter:… Mukul Goyal
- Re: [Roll] knowing which multiple metrics matter:… Mukul Goyal