Re: [dnssd] DNS Name Autoconfiguration for Home Network Devices

Alf Watt <alf@istumbler.net> Tue, 18 November 2014 18:46 UTC

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From: Alf Watt <alf@istumbler.net>
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Cc: Brian Haberman <brian@innovationslab.net>, Myung-Ki Shin <mkshin@etri.re.kr>, "dnssd@ietf.org" <dnssd@ietf.org>, Jung-Soo Park <pjs@etri.re.kr>, Ted Lemon <Ted.Lemon@nominum.com>, Sejun Lee <prosejun14@gmail.com>
Subject: Re: [dnssd] DNS Name Autoconfiguration for Home Network Devices
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The proposal may have merit for other reasons but in terms of resource usage for IoT devices it’s very instructive to look at existing products.

The Phillips Hue lights are built around a 32 ARM core [1] with limited RAM (128kb). The Nest Protect smoke detector is also built around a similar 32bit ARM core from Freescale, the K60[2].

Both of these are attached to a Zigbee radio, which provides sufficient bandwidth for DNS-SD over mDNS, as per our charter[3].

Devices which need service discovery on batteries will very likely be using layer-2 discovery mechanisms for power consumption reasons (i.e. BT-LE). 

I have a hard time imagining that a device with much less capabilities than above will be a useful internet node. If it can't afford to run a simple discovery service then what is it doing on the network?

Best,
Alf

[1] http://www.digchip.com/datasheets/parts/datasheet/456/STM32F217VET6.php
"ARM-based 32-bit MCU, MB Flash/128+4KB RAM, crypto, USB OTG HS/FS, Ethernet, 17 TIMs, 3 ADCs, 15 	comm. interfaces & camera"
[2] http://cache.freescale.com/files/32bit/doc/data_sheet/K60P100M100SF2V2.pdf?fpsp=1&WT_TYPE=Data%20Sheets&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation
[3] http://datatracker.ietf.org/wg/dnssd/charter/

> On Nov 14, 2014, at 10:34 PM, Mr. Jaehoon Paul Jeong <jaehoon.paul@gmail.com> wrote:
> 
> Alf,
> For embedded such as printers, cameras that have power and capacity equivalent to smartphone,
> you are right.
> 
> For low-power low-capacity devices, such as light bulb and smoke detecting sensor,
> I think that running server(s) seems not viable 
> even though I have no exact number of target memory and cpu size 
> for such low-power low-capacity IoT devices.
> 
> Is there anyone else to comment on the hardware specification of such IoT devices?
> 
> Thanks.
> 
> Paul  
> 
> ===========================
> Mr. Jaehoon (Paul) Jeong, Ph.D.
> Assistant Professor
> Department of Software /
> Department of Computer Engineering
> Sungkyunkwan University
> Office: +82-31-299-4957
> Mobile: +82-10-4758-1765
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> CPS Lab Website: http://cpslab.skku.edu
> Personal Homepage: http://cpslab.skku.edu/people-jaehoon-jeong.php
> 
>> On Fri, Nov 14, 2014 at 12:02 PM, Alf Watt <alf@istumbler.net> wrote:
>> I’m confused, the mDNSResponder code is very lightweight and already runs on embedded devices such as printers, cameras and may other low-memory and low-cpu devices.
>> 
>> What is your target memory and cpu size for an IoT device? Given that we’ve been using mDNS for more than a decade, the steady pace of improvement in semiconductors means that even the smallest device will have more than sufficient resources for mMDS.
>> 
>> Best,
>> Alf
>> 
>>> On Nov 14, 2014, at 1:34 PM, Mr. Jaehoon Paul Jeong <jaehoon.paul@gmail.com> wrote:
>>> 
>>> The solution in RFC 6762 (Multicast DNS) section 9 is viable for regular computers, 
>>> such as laptop, desktop, and smartphone that can afford to run mDNS responder.
>>> For IoT devices, such as light bulb and fire detecting sensor, that have limited memory and storage,
>>> mDNS seems not viable for the DNS naming for them.