Re: [Detnet-dp-dt] [EXT] DETNET Synchronization Slides

[Tal Mizrahi <[e-mail]>]

Hi Loa,

Right, that is my understanding as well.

Thanks,
Tal.

>-----Original Message-----
>From: Detnet-dp-dt [mailto:[e-mail]] On Behalf Of Loa
>Andersson
>Sent: Monday, February 13, 2017 11:48 AM
>To: [e-mail]
>Subject: Re: [Detnet-dp-dt] [EXT] DETNET Synchronization Slides
>
>Tal and Jouni,
>
>I'm trying to make heads and tails of this.
>
>I think we have the three scenarios in the slides + 1 or 2 more.
>
>0.5 - raw,   i.e. running over a network without DetNet cpabilities
>1.  - Naive, i.e. running over a DetNet network
>1.5 - On-path-support, on a subset of the nodes 2.  - On path support (all nodes)
>3.  - Time as a service
>
>Nat that we need to include all this in the list, I just want to have an
>understanding that DetNet capabilities improve the things.
>
>/Loa
>
>On 2017-02-13 17:01, Tal Mizrahi wrote:
>> Hi Jouni,
>>
>> That is a fair point. If only the PW nodes function as TCs, then indeed the
>accuracy will be lower.
>> I added a clarification about this in slide 6.
>>
>> The updated slides are attached.
>>
>> Thanks,
>> Tal.
>>
>>> -----Original Message-----
>>> From: Jouni Korhonen [mailto:[e-mail]]
>>> Sent: Thursday, February 09, 2017 10:35 PM
>>> To: Tal Mizrahi
>>> Cc: [e-mail]
>>> Subject: Re: [EXT] [Detnet-dp-dt] DETNET Synchronization Slides
>>>
>>> Tal,
>>>
>>> I understood that in 2) the TC function would only be in the PW nodes
>>> we define leaving all intermediate "normal" LSRs between PW nodes as
>>> a source of higher inaccuracy. If this was not a correct
>>> understanding then the value in 2) is likely too high.
>>>
>>> - Jouni
>>>
>>>
>>>> On 08 Feb 2017, at 23:22, Tal Mizrahi <[e-mail]> wrote:
>>>>
>>>> Hi Jouni,
>>>>
>>>> Sorry for not explaining the accuracy numbers on slide 6 further. I
>>>> made some
>>> changes following the discussion, and also added notes saying that
>>> the accuracy will depend on the network topology and on the number of
>hops.
>>>>
>>>> Regarding approach 2, I believe sub-microsecond accuracy can
>>>> certainly be
>>> achieved using transparent clocks in a real network. There are quite
>>> a few publications that show this. Here are a couple:
>>>> - For example, China Mobile have revealed in a keynote lecture in
>>>> ISPCS 2014
>>> that they have measured an accuracy of 266 ns over 30 hops of
>>> transparent clocks. Unfortunately, this presentation is not in the
>>> public domain, but a short version of it is available
>>> (https://www.ietf.org/mail- archive/web/tictoc/current/pdfp9ceHphbcE.pdf).
>>>> - Another example:
>>>
>http://wwwen.zte.com.cn/endata/magazine/ztecommunications/2010Year/no
>>> 3 /articles/201009/t20100913_191838.html
>>>> But again, this entirely depends on the nature of the network.
>>>>
>>>> Regarding approach 1, the accuracy will entirely depend on the
>>>> network
>>> topology (the number of hops, the physical distance, the type of
>>> intermediate nodes, the delay variation). Hundreds of microseconds is
>>> just an example. Some of the research I took part in showed that in a
>>> multi-site public cloud network you can achieve a precision on the
>>> order of hundreds of microseconds using PTP without on-path support
>>> (https://sites.google.com/site/talmizrahihome/files/TaaSInfocomFinal.
>>> pdf?attred irects=0). But again, this entirely depends on the nature
>>> of the network.
>>>>
>>>> Please let me know if there are further comments.
>>>>
>>>> Thanks,
>>>> Tal.
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: Jouni Korhonen [mailto:[e-mail]]
>>>>> Sent: Wednesday, February 08, 2017 8:15 PM
>>>>> To: Tal Mizrahi
>>>>> Cc: [e-mail]
>>>>> Subject: [EXT] Re: [Detnet-dp-dt] DETNET Synchronization Slides
>>>>>
>>>>> External Email
>>>>>
>>>>> -------------------------------------------------------------------
>>>>> ---
>>>>> Thanks Tal,
>>>>>
>>>>> Didn't we also agree adjusting the slide 6 "typical accuracy" numbers:
>>>>> 1) <1ms or hundreds of us
>>>>> 2) <tens of us
>>>>> 3) <1us
>>>>>
>>>>> - Jouni
>>>>>
>>>>>
>>>>> --
>>>>> Jouni Korhonen, Broadcom Ltd.
>>>>> M: [phone]
>>>>>
>>>>>> On Feb 7, 2017, at 10:51 PM, Tal Mizrahi <[e-mail]> wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> The slides from today's weekly meeting are attached.
>>>>>> I slightly updated them after the meeting based on the comments.
>>>>>>
>>>>>> Cheers,
>>>>>> Tal.
>>>>>> <Synchronization in
>>>>>
>DETNET.pptx>_______________________________________________
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>>>>>> https://www.ietf.org/mailman/listinfo/detnet-dp-dt
>>>>
>>
>>
>>
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>
>--
>
>
>Loa Andersson                        email: [e-mail]
>Senior MPLS Expert                          [e-mail]
>Huawei Technologies (consultant)     phone: [phone]
>
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