Re: [manet] MANET meeting at IETF85

[Ulrich Herberg <[e-mail]>]

Hi JP,

On Oct 14, 2012, at 0:07, "JP Vasseur (jvasseur)" <[e-mail]> wrote:

> Hi Ulrich,
> 
> On Oct 14, 2012, at 3:13 AM, Ulrich Herberg wrote:
> 
>> Hi Cédric,
>> 
>> On Sat, Oct 13, 2012 at 11:16 AM, C Chauvenet <[e-mail]> wrote:
>>> [...]
>>> 
>>> The distinction between MANET and LLNs seems to be vanish here.
>>> This brings us back to the summer discussion between what is a MANET and what is a LLN that did not really fostered on a consensus.
>>> WG chairs could help there, as it is their related scope.
>> 
>> 
>> I am not suggesting to revive a discussion of the definition of a MANET vs LLN.
> 
> JP> Mei neither - this is why, if you suggest to indicate the applicability of the protocol in the document which makes total sense, the WG should exclude LLNs from
> this ID explicitly.


I disagree. How can we exclude it from the document when it is as a matter of fact used in LLNs?  I am just saying that if LOADng is to be accepted by the WG, it has been clearly expressed in the last meeting that it is too focused on LLNs, and should instead focus on the general MANET case. I agree with that. Mentioning one, out of many use cases, in particular when people actually deploy it in that use cases seems just fair, and does not cause any overlap between two working groups.



> 
>> I did not bring up this discussion. All I am saying is that MANET is chartered to come up with a reactive protocol. And I believe it should be allowed to mention where a protocol is used in deployments. 
>> 
>> 
>>  
>>> My vision is that LLNs are more constrained than MANET for the following criterion : Power consumption, Loss of the media, Computation capability, Throughput.
>>> What do you think ?
>>> My vision is also that the level of constraints of LLNs should not be considered in a MANET protocol.
>>> Do you agree ?
>> 
>> 
>> Since you ask here...In my personal opinion,  LLNs are a 100% subset of a MANET. Both are usually multi-hop, often wireless, with constrained routers, in many cases incoming packets leave a router on the same interface that they have been received on, and the topology is dynamic.
> 
> JP> Well, in this case, pushing your reasoning a bit further, this may very well apply to OSPF, ISIS, … too.


These protocos don't cope well with lossy channels and dynamic topology changes.

> I clearly do not think that LLNs are 100% subset of MANET; there is a tremendous difference between several dozens of highly constrained fixed routers interconnected
> by very lossy links providing a few KBits/s and several hundreds of routers with high mobility interconnected by Wifi links.

Nobody ever said that MANETs are interconnected by wifi only, or anything about limited size of the network (quite the contrary, they are intended to be very large). Also, MANETs such as Funkfeuer are non-mobile.


> 
>> MANETs, IMO, have a larger range of "constrained routers", from very constrained routers (e.g. LLN) to somewhat constrained routers (e.g. community networks) to non-constrained routers (e.g. certain military deployments). LLN is focused on extremely constrained devices.
>> However, I don't say that we should revisit the way how the Routing Area distributed the tasks in the WGs, nor do I suggest to change the charters.
> 
> JP> IF that were the case, we would not have formed two WG but one.


I don't want to go in there.


> 
>> 
>>  
>>> 
>>> I'm trying to figure out if LOADng is efficient over a mains-powered computer using Wifi, a 8K/48K RAM/ROM device,  or both (cover such a wide range would be magical !).
>> 
>> I cannot answer this question, as I have not deployed LOADng on a 8K/48K RAM/ROM device. Those who have deployments and are willing to disclose details, may have more details. Just one comment: I have implemented numerous ad-hoc protocols (OLSRv2, LOADng, RPL, DSDV, ...). LOADng is by far the simplest to implement and has the least lines of code (by far) compared to all these other protocols that I have implemented. If you can run any of these beforementioned protocols on such a device, you can certainly run LOADng on it.
> 
> JP> I wish life was so simple … The argument around simplicity is a recurring one. And unfortunately, simple protocols do not always WORK … I could actually show
> you, taking real-life networks (no simulation), how a (simple) reactive routing protocol would break in a LLN.


As a matter of fact, there are large-scale deployments of LOADng by industry. If LOADng was not working, I doubt that there would be any money spent on that.
And your last argument is not helpful; I am convinced that for any Standards Track routing protool, I can show you scenarios where it breaks (whereas in other scenarios it works fine). 

Best
Ulrich



> 
>> 
>>  
>>> 
>>> I see in the interop report http://tools.ietf.org/html/draft-lavenu-lln-loadng-interoperability-report-02 in section 3 :
>>> [...]
>>> So my first guess is that LOADng is suitable for what I called "mains-powered computer using Wifi" ?
>> 
>> 
>> I think Jiazi has already replied to that in a later mail. Interop != performance test. LOADng (like any other MANET protocol) can run on any medium. Testing it on wifi is a simple thing to do. Interop tests are solely to find out if messages can be parsed correctly, and if the implementations behave according to the specification. 
>> 
>> As Jiazi pointed out correctly, I don't understand why we have this discussion before you have seen the latest LOADng revision. 
>> 
>> Best
>> Ulrich
>>  
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