Re: [T2TRG] Comments on draft-hong-iot-edge-computing-02

[홍용근 <[e-mail]>]

Hi. Alex.

Thanks a lot for your comments.
With respect to all your comments on the lack of the evidence data or references, we will clarify them in the next revision.
Other than that, please find the answers in-line.

Best regards.

Yong-Geun.

From: Alessandro Bassi [mailto:[e-mail]]
Sent: Tuesday, April 2, 2019 7:44 PM
To: 홍용근; [e-mail]
Subject: Comments on draft-hong-iot-edge-computing-02


Dear authors

I've read this draft and I also have a few comments:

1. Introduction

"Nowadays, most IoT services are based on Cloud computing since it can provide virtually unlimited storage and processing power."

Do you have any statistics to show that really most of IoT services are on the cloud?

"about a half of data is stored, processed, analyzed and acted upon close to the data producer"

Again, can you quote a source for this claim?

[Hong] We think this is a common sense and it is easy to predict.



3.

I think you should introduce a definition of Edge computing and Cloud computing here rather than Section 5, together with the definition of Fog (and Mist maybe?).

[Hong] We are thinking of having individual sections or subsections on Edge computing and Cloud computing as Matthias suggested by the mailing list.



3.1

In your definition, IoT does not have any actuation - do you really mean it? As there are dozens of definitions for IoT, I would recommend maybe to pick one of the existing ones.

[Hong] IoT could include sensors, devices, and actuators.  We tried to provide very general concept of IoT since there are dozens of definitions as you said.



3.2

"IoT is generally characterized by real world small things that are widely distributed but have limited storage and processing power"

RFC 7228 defines the terminology for constrained nodes (and networks).

[Hong] We will take a look at RFC 7228. And, Carles already responsed it.



3.3

In general, it is not clear to me the aim of this paragraph. You already stated that the massive amount of data generated by IoT Devices will need to be processed at the edge. This architecture for sure makes sense, but it's not new. I don't see any "paradigm shift". Unless you have some data that shows that until 20XX the YY% of all IoT application were using dummy sensors and actuators, and the actual processing was taking place remotely, while the trend in the last ZZ years is that the processing is happening "closer" to the data collection points - but in this case you would need to explicitly write the source. As well, there is the need of defining the closeness (on device? on some intranet directly connected to the device? etc etc ...).

"Now with IoT, we will reach the era of post-Clouds where unprecedented volume and variety of data will be generated by things at edge networks and many applications will be deployed on the edge netwoks to consume these IoT data."

Is this your opinion?

[Hong] Don’t you agree with it? Or are you asking the source as well? We will clarify this as well in the next revision.



"Some of the applications may have very short response times, some may contain personal data, and others may generate vast amounts of data. Today's Cloud based service models are not suitable for these applications."

Why?

[Hong] Do you think that today's Cloud based service can satisfy any IoT applications which even requires very short response times and privacy? Or asking a source again? We don’t catch what you are asking.



4.1

"These requirements for latency are difficult to achieve by today's Cloud services."

No. IMO it's simply impossible. IP is a connectionless, unreliable protocol by definition. IoT applications may require hard-real time response time, which, from the engineering point of view, it's not possible to guarantee over an IP layer.

[Hong] In some point, you are right. We tried to focus the distance between the provider of data and the consumer. As you know, the long distance between communication nodes will make delay.



4.2

"With an exponential rate, IoT data is generated by the massive things [...] "

what do you mean by massive things?

[Hong] Since we stated in subsection 3.1, things are various embedded systems such as home appliances, mobile equipment, wearable devices, etc. We may change “massive” to “numbers of”.



"connected into the Internet [Kelly]<https://tools.ietf.org/id/draft-hong-iot-edge-computing-01.html#Kelly> and extremely high network bandwidth is required to send all the data to the cloud."

Do you have any data to show? What are the bandwidth requirements?

[Hong] We thought that it was very trivial that sending all the IoT data to the cloud  requires high network bandwidth since the generating IoT data is massive. We will try to include more specific data on this in the next revision.



"Since 90% of the IoT data generated by the endpoints will be stored and processed locally rather than in the cloud [...]"

Do you have any study to back this claim?

"[...] sending all the IoT data to the cloud is often unnecessary."

well, if it's already processed, indeed it makes no sense to send it ... I think this sentence should be rephrased.

[Hong] IMO, depending on service, IoT data may be sent to cloud even though it is already processed at edge.



"Or sometimes it is prohibited due to regulations and data privacy concerns."

Can you make any example?

[Hong] It could be possible in healthcare service. We may modify “it is prohibited” to “it MAY BE prohibited”.



4.3

"Many IoT things such as sensors, data collectors, actuators, controllers, cars, drones, etc., have very limited hardware resources."

I'm not quite sure that a car has very limited hardware resources ...

[Hong] Yes, cars have more enhanced hardware resources compared to others. We will delete “cars” there.



In general, what is an "IoT Thing"?

 "Many constrained IoT things cannot rely solely on their limited resources to meet all their computing needs."

There's a flaw IMO in this concept. Assuming that for "IoT things" you mean "device", if I am a company developing some devices I have a clear business idea (or at least I should). If _as an example _ I am selling cameras, I might choose to embed processing power on the camera itself for image recognition, or else just transmit the images to an endpoint, on the cloud or wherever. The "computing need" here seems linked to a specific service (such as, detecting bad guys into a crown of people). The device itself does not have any computing need: it may have some computing functionality, and expose some resources (such as doing facial image recognition on-device), but per se it has no needs. Therefore, you should rephrase the sentence such as

'Many Class <you choose the class here according to RFC 7228> and below devices do not have the processing capabilities to fulfill the needs of complex services'.

"It is not practical to require everyone to interact directly with the cloud."

The cloud here is the Internet?

[Hong] No. We meant it cloud.



"This is because these interactions require resource-intensive processing and complex protocols."

I would disagree. IMO the main reason why a centralized architecture has issues is for scalability. While I can connect a limited number of constrained resources to a service running on some cloud, scaling up the number poses obvious issues of network traffic and processing. If I have cameras transmitting videos to a server, once the channel is set up, there is no resource-intensive processing nor complex protocols - no more that if a camera processes the image itself and send an interrupt every time a bad guy is detected.

[Hong] We will clarify this as your comments in the next revision.



4.4

"Cloud services will have difficulty providing uninterrupted services to devices and systems such as vehicles, drones, and oil rigs that have intermittent network connectivity to the cloud."

I'm sure the 5G guys will disagree with this ... :)

[Hong] In some point, you are right. But, in real circumstances, not only 5G, but also 2G, 3G, 4G and other wireless technologies could be used for IoT services.



4.5

"When IoT data is sent to the cloud which is the end point in the traditional end-to-end communication system, privacy of the data is a challenge since it may travel across multiple routers to the cloud."

that's why data is encrypted ... right?

[Hong] Yes, the encryption is a solution for the privacy issue. In this draft, we discuss the challenges which does not mean that there is no solution for those.



5.1

In general, there are two different architectures:

- centralised one, with dummy endpoints and all processing done at the "core".

- decentralised one, with processing done (in all or in part) at the edge and only relevant data passed to the core.

This draft is making the point that the second architecture is better, for a number of reasons. That is fine. What needs to be clear though is why is better, under which conditions ASO. The text here does not give any proof of this being the case.

[Hong] We will clarify this in the next revision.



5.1.1

"As tremendous IoT sensors, IoT actuators, and IoT devices [...]"

Tremendous?

In my view, a Device IS A sensor or an actuator. Here you list the three, so what is a device in this context?

[Hong] We will revise the sentence.



"[...] are connected to the Internet, IoT data volume from these things are expected to increase explosively."

why? Besides, usually a Device is not directly connected to the Internet. A temperature sensor is just connected to a proxi. A smart shoe is just connected to a smart phone via BLE. Usually, constrained devices do not have enough "power" to hold a complete Internet stack, and they are connected to a gateway.

"And it is expected that much of this high volume of IoT data is produced and/or consumed within edge networks, not to traverse through cloud networks."

Do you have any source for this?

[Hong] You can find many future prediction of IoT services and traffic volumes. And we also believe this situation and we have tried to prepare this problem.



Besides, why it should "traverse" cloud networks?

" Until now, mainly IoT data generated IoT things are transferred and accumulated in a remote server and to store IoT data in a remote server requires expensive cost of transmission and storage."

Do you have any source for this?

"To mitigate the cost of transmission and storage, it is required to divide IoT data into two types of data; one is stored in edge networks and the other is stored in cloud networks."

According to which criteria data may be stored on the edge or transferred?

[Hong] It depends on IoT services. Some IoT data will be consumed at the edge and some IoT data will be delivered to cloud.



5.1.3

"If it is possible to separate IoT data in edge networks and cloud networks,"

While it's possible to interpret this sentence, if your aim is to say that data generated by IoT devices can be stored and processed either at the edge or at the core, I think it would be better to rephrase as such.

"Edge computing can do more functions with IoT data in edge networks. Because Edge computing has the capabilities to handle IoT data in edge networks, it is also possible to analyze IoT data to provide enhanced IoT services such as intelligence."

[Hong] Thanks for your suggested text. It looks better. We will reflect this in a next revision

This is really not clear to me.

6

In general, I think the use cases as they are stated are rather weak. I would omit this section unless there are specific data to be shown. I make an example for the smart construction: you write that today there is a certain amount of data that can be recorded and sent to a remote service for processing, and this has a cost (LTE and AWS). Indeed - but it's not that deploying a gateway on a construction site (or nearby) comes for free. Statistical analysis and ML can be applied on a remote server - actually, as the remote server is likely to be more powerful and has access to a larger number of data sets, the ML algorithm may work better from remote than on the edge. The communication time - given a decent connectivity - is irrelevant given the likely "latency time" of the inspector. On the other hand, if you can make a precise claim on cost saving, or on scalability over certain numbers of connected devices, then it's probably good to have a section outlining the boundaries in specific use cases over which a distributed architecture has clear advantages.

[Hong] I agree that the use cases are rather weak. Because we are implementing some trial services and products, there are limitation. During the progress our implementation, we will add more practical and specific use cases. If you have a relevant information, it is appreciate to provide texts.



thanks! best,

--alex