Re: [6lowapp] [6lowpan] hardware trends, new vs. existing protocols [Re: 4861 usage in LLNs]

[Robert Cragie <[e-mail]>]

So it is again down to trying to find the intersection between 
well-established and well-known protocols which work in networks with 
limited resources whose nodes have limited resources. There is a chance 
that despite the extent of the IETF smorgasbord, existing protocols may 
need to be tweaked or updated to accommodate these requirements. 
However, this must be the underlying aim - not to reinvent, but to take 
verbatim where possible and adapt where necessary. Where there is a 
clear demand, solutions will appear based on existing protocols plus 
adaptations - for example, VoIP.

Regarding resource: There will be classes of devices which currently 
will not support IP packets as the resource constraints are too high, 
e.g. self-powered switches where the power budget is so constrained you 
can barely get a squeak out of them. Do we want to accommodate these 
devices in CoRE etc.? Probably not, and so it makes sense to develop the 
network which suits those devices and proxy them on a gateway. On the 
other hand, I think we have established that we don't want to 
persistently continue to develop a plethora of coexisting but 
non-interoperating networks all connected to the internet through a 
hodge-podge of application gateways for the sake of it. This is the 
reality today and it could be argued that this has stifled the 
development of the highly-connected "Internet of Things" we have all 
been dreaming about; it is a solution but a clumsy one and one which 
doesn't scale well.

Regarding bandwidth: I remember back in the early 90's being able to 
look at basic websites over a V32.bis (14400 bps max.) modem; whilst the 
experience could be frustratingly slow, it was usable. And that was an 
online, interactive experience. So whilst we need to consider the 
arguments about bandwidth, I think that realistic traffic scenarios need 
to be carefully looked at before ruling some solutions out. I am sure 
there is already a plethora of experience from many of the contributors 
to this group who already work in this area.

So we come down to the limited ROM/RAM devices which sit uneasily 
between the clearly capable devices currently available and the very 
constrained and highly specific devices for certain types of network. 
Which way do we want to push them? On the basis that these are the 
devices which will become obsolete first, I would push them towards the 
constrained side and say they are all proxied. In which case, 
CoRE/ROLL/6LoWPAN becomes becomes focused on the more clearly capable 
devices and therefore, as said at the beginning of this e-mail, based on 
protocols taken verbatim where possible and adapted where necessary.

Robert

Kris Pister wrote:
> Richard -
> I think that today's things are being designed with wonderful chips 
> like your Ember EM351 and EM357
> which have 128kB and 192kB of flash and lots of RAM; like the Jennic 
> JN5148, the Freescale MC13224, the Dust DN2510.
> They can run IP, they will run IP, and in many cases they do run IP.  
> We all agree on that, and we're all excited about that. The debate 
> centers on how many new protocols we need to invent, vs. how many we 
> can adopt or adapt, with the existing hardware, and with an eye toward 
> where technology trends are taking us.  My concern, like yours, is 
> over the rate of adoption.  If the fastest path to broad adoption is 
> to create new protocols for routing, ND, transport, and applications, 
> then by all means let's do that.  I'm concerned, however, that this 
> has not been a uniformly successful approach for wireless sensor 
> networks in the past. :)
> Many of us believe that we will see the fastest adoption by minimizing 
> the number of new protocols.  We might be wrong, and that's the debate.
>
> ksjp
>
> Richard Kelsey wrote:
>>    Date: Mon, 09 Nov 2009 22:12:03 -0800
>>    From: Kris Pister <[e-mail]>
>>
>>     > Abandoning the installed base just goes to reinforce the idea
>>     > that IP isn't an appropriate technology for things.
>>
>>    Michael - I think that we have the same goal, but I disagree with 
>> that    statement.  I think that re-writing every protocol from 
>> discovery    through transport to applications, from scratch, is what 
>> reinforces the    idea that IP isn't an appropriate technology for 
>> things.
>>
>>    I realize that there are pressures from an installed base, but at 
>> this    point it's a tiny fraction of the overall potential.  If we 
>> let the 1%    installed base dictate the path for the next 99%, we 
>> should do our best    to ensure that it's the right path.
>>
>> Taking these two paragraphs together, you seem to be saying
>> that IP is an appropriate technology for tomorrow's things,
>> but not necessarily for today's.  While the hardware will
>> obviously improve over time, we still need to pick some
>> target platform.  The current 6lowpan charter gives 32K of
>> flash as an example and mentions 802.15.4 repeatedly.  Are
>> you suggesting that we recharter? 
>> The increasing capabilities of the hardware does give us the
>> reassuring prospect that the longer we take the solve the
>> problems the easier it will be to so.
>>
>>                                 -Richard Kelsey
>>   
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