Re: [Roll] mixture of storing and non-storing nodes

Hi!

A bit more comments in-line ;)

On Aug 25, 2012, at 9:33 AM, 정종수 wrote:

> Hi Michael.
> 
> 2012. 8. 25. 오전 4:23 "Michael Richardson" <mcr+ietf@sandelman.ca> 작성:
> 
>> 
>>  OG> John Ko posted a draft a few days ago about how we might accommodate a
>>  OG> mixture of storing and non-storing nodes in a network more efficiently
>>  OG> than making one of them leaf nodes. Searching through the ROLL mail
>>  OG> archives, it was clear at the time that there was no use case for
>>  OG> having a network that has a mixture of storing and non-storing
>>  OG> nodes.
>> 
>>  JP> I cannot agree more - actually we even have a partial to the
>>  JP> problem during the initial design phase and the WG collectively
>>  JP> decided not to mix storing and non-storing in light of the added
>>  JP> complexity. I would also appreciate the feedback of the WG on
>>  JP> this, and not add complexity unless this becomes a strong
>>  JP> requirement. 
>> 
>> I believe that use cases for storing and non-storing nodes would appear
>> as optimizations (particularly in the p2p heavy LLNs) if we could figure
>> out how to make it work.
>> 
> 
> You're right. Additionally, mixture of storing and non-storing nodes can cause inefficient upwards routing in the current RPL. Because nodes that can support only different MOP from the root's MOP should act as a leaf node. Furthermore, if the leaf node is an only node that is at intermediate place physically to forward upstream traffic, not only downwards but also upwards routing will not work from this point.
> 
>> I think that the major problem was that nodes below the root needed to
>> know if there downstreams nodes were storing or not, and thus
>> non-storing nodes wound up picking up significant resource impact, when
>> those nodes were supposed to be lighter weight.
>> 

Resource is by far one of the most important factors. One of the characteristics of this draft is to allow both modes to be possible. If you have the resources, then be a storing mode! If not, you always have the option of being a non-storing mode... its just that with the draft, we can mix these two modes together. The two modes have their own benefits so let's keep them and allow them to mix together so that we can perform, as mentioned above, optimizations to the RPL network.

Thanks for your feed back!

-John

>> -- 
>> Michael Richardson
>> -at the cottage-
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> 
> Thank you.
> -Jongsoo
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