Re: [6lo] working group last call (wg lc) on https://datatracker.ietf.org/doc/draft-ietf-6lo-deadline-time/

["Georgios Z. Papadopoulos" <[e-mail]>]

Dear Lijo,

Many thanks for the clarification.
I am good now.

Best,
Georgios

____________________________________

Georgios Z. Papadopoulos, Ph.D.
Associate Professor, IMT Atlantique, Rennes

web: 	 www.georgiospapadopoulos.com <http://www.georgiospapadopoulos.com/>
twitter: 	@gzpapadopoulos <https://twitter.com/gzpapadopoulos?ref_src=twsrc%5Etfw&ref_url=http://georgiospapadopoulos.com/>
____________________________________

> On Jul 24, 2018, at 12:04, Lijo Thomas <[e-mail]> wrote:
> 
> Dear Georgios,
>  
> Thanks for the feedback, responding to your query : 
>  
> Deadline Time (DT) by itself does not guarantee deterministic behaviour, but its information enables intermediate nodes to implement delay sensitive scheduling and routing algorithms towards achieving deterministic behaviour.
>  
> As a use case application of our draft,  we implemented a basic EDF policy in OpenWSN 6tisch stack. 
>  
> Please find the link for our openwsn implementation
>  
> https://github.com/openwsn-berkeley/openwsn-fw/tree/develop/openapps/uexpiration <https://github.com/openwsn-berkeley/openwsn-fw/tree/develop/openapps/uexpiration>
>  
>  
> Thanks & Regards,
> 
> Lijo Thomas 
> 
>  
> From: 6lo [mailto:[e-mail]] On Behalf Of Georgios Z. Papadopoulos
> Sent: 24 July 2018 13:49
> To: Lijo Thomas
> Cc: [e-mail]; [e-mail]; Malati Hegde; Samita Chakrabarti; Gabriel Montenegro; lo; Charlie Perkins; [e-mail]
> Subject: Re: [6lo] working group last call (wg lc) on https://datatracker.ietf.org/doc/draft-ietf-6lo-deadline-time/
>  
> Hello Lijo,
>  
> Thank you so much for your detailed comments. I appreciate it very much.
> I am happy with your response, I just have one last clarification point, see below:
>  
>  
>> On Jul 24, 2018, at 09:38, Lijo Thomas <[e-mail] <mailto:[e-mail]>> wrote:
>>  
>> Dear Georgios,
>>  
>> Thanks for your valuable suggestions and we really appreciate for taking your valuable time for the review .
>>  
>> Please find our comments inline below marked as (*** [LT]) 
>>  
>> We will be happy to receive your further inputs !!!
>>  
>>  
>> Thanks & Regards,
>> 
>> Lijo Thomas 
>> 
>>  
>> From: 6lo [mailto:[e-mail] <mailto:[e-mail]>] On Behalf Of Georgios Z. Papadopoulos
>> Sent: 17 July 2018 21:40
>> To: [e-mail] <mailto:[e-mail]>
>> Cc: [e-mail] <mailto:[e-mail]>; [e-mail] <mailto:[e-mail]>; Malati Hegde; Samita Chakrabarti; Gabriel Montenegro; lo; Charlie Perkins; [e-mail] <mailto:[e-mail]>
>> Subject: Re: [6lo] working group last call (wg lc) on https://datatracker.ietf.org/doc/draft-ietf-6lo-deadline-time/ <https://datatracker.ietf.org/doc/draft-ietf-6lo-deadline-time/>
>>  
>> Dear Lijo and co-authors,
>>  
>> I went through the draft, please find my comments below:
>> — — 
>>  
>> High level comments:
>> */ [GP] The draft defines the Deadline Time (DT), but it is not clear to me how the arrival of the datagram within this pre-defined DT period is guaranteed?
>> Indeed, the draft provides the necessary DT information, however, the only action I could observe is the delay-sensitive datagram to be dropped if the indicated DT is elapsed.
>>  
>>  
>> *** [LT] Yes, the Deadline Time (DT) specifies the maximum allowable delay
>> before which the packet should be delivered to the destination. The proposed
>> draft provides a mechanism for transporting the DT information. By incorporating
>> deadline based scheduling/routing mechanisms within the intermediate nodes
>> using DT, one could guarantee deterministic behavior in terms of delay. 
>  
>  
> [GP] Would you agree that this draft do not guarantees deterministic behavior in terms of delay, but it provides
> the information of maximum allowable delay for a packet to be delivered to the destination?
>  
> To be more precise, for instance, lets us consider the following multi-hop network A—> B —> C.
> According this draft, it will required 2 timeslots (or 20ms) for a packet to be delivered at the DODAG Root C.
> However, if there is an external interference from A to B, then A may need to retransmit multiple times
> in order the datagram to be received by B. Then there are two options according to the draft:
> a) the datagram is dropped, to reduce the traffic, energy consumption.
> b) the datagram is delivered even if the deadline time is crossed, i.e., as you said in your e-mail “in some scenarios where the intention is also to know the total delay experienced by the packets in a network”
>  
> In both bases, a and b, there is no guarantee that the datagram will be delivered in predefined time, i.e., in deterministic behavior. 
>  
> — — 
> Thank you so much,
> Georgios
>  
> ____________________________________
>  
> Georgios Z. Papadopoulos, Ph.D.
> Associate Professor, IMT Atlantique, Rennes
>  
> web:     www.georgiospapadopoulos.com <http://www.georgiospapadopoulos.com/>
> twitter:            @gzpapadopoulos <https://twitter.com/gzpapadopoulos?ref_src=twsrc%5Etfw&ref_url=http://georgiospapadopoulos.com/>
> ____________________________________
>  
>  
>  
> 
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