Re: [manet] Reactive Protocol Situation

[Don Sturek <[e-mail]>]

Hi Phil,

As you probably know, we (the ZigBee Alliance IP networking folks) are
using ROLL RPL.  To address the asymmetric link issue, we are using this
draft:   
http://datatracker.ietf.org/doc/draft-kelsey-intarea-mesh-link-establishmen
t/, and specifically the Link Quality exchange between neighbors.

This, along with a policy of adjusting routing information for these links
helps get around asymmetric link issues.

The MLE draft was written to be routing protocol neutral and could be
re-used for any commercial deployment and any mesh routing protocol.

Don



On 11/1/12 9:45 AM, "Philip Levis" <[e-mail]> wrote:

>On Nov 1, 2012, at 9:27 AM, Dearlove, Christopher (UK) wrote:
>
>> They can be good evidence of the failure of protocols ;)
>> 
>> But what is clear to me is that one important issue (and another of my
>>posts is attempting to both be more precise, as well as going elsewhere)
>>is the handling of unidirectional links. So any good evidence needs to
>>consider those.
>
>Since communication in wireless is rarely binary, I think the more common
>term is asymmetric links. I'm confused; I don't believe that unit disc
>models capture asymmetric links. Is the implied statement that RPL
>doesn't properly handle asymmetric links but LOADng does? I think this
>came up in draft-clausen-lln-rpl-experiences and there was some
>discussion on the ROLL list about it. The neighbor set in RPL is defined
>in 8.2.1:
>
>"First, the candidate neighbor set is a subset of the nodes that can be
>reached via link-local multicast."
>
>then in DIO processing (8.2.3.1) it reads:
>
>"As DIO messages are received from candidate neighbors, the neighbors may
>be promoted to DODAG parents by following the rules of DODAG discovery as
>described in Section 8.2."
>
>I want to be clear here; I haven't read deeply about LOADng, thought
>about it much, or experimented with it at all. So I have zero to say
>about LOADng's strengths and weaknesses.
>
>But just because somebody publishes (and republishes) a draft saying
>something doesn't mean it's true. There are, in my opinion, some very
>valid points in draft-clausen-lln-rpl-experiences that relate to
>fundamental design decisions in RPL. For example, I think that the issues
>raised about the state requirements of floating DODAGs and RPL message
>fragmentation are valid and reasonable and something we need to look at.
>
>However, there are others that are the result of naive mistakes anyone
>can make when implementing any wireless routing protocol, such as link
>asymmetry and protocol convergence. Unfortunately the draft doesn't
>distinguish the two. Implementing a protocol poorly then saying it
>doesn't work isn't particularly meaningful. As I said in Paris, I thought
>the draft is valuable because it outlines many of the basic mistakes one
>makes the first time you try implementing a wireless routing protocol.
>
>Phil
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