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Re: [Detnet-dp-dt] [EXT] Re: Data Plane Approach - Synchronization Traffic

Jouni Korhonen <jouni.korhonen@broadcom.com> Thu, 26 January 2017 18:39 UTC

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From: Jouni Korhonen <jouni.korhonen@broadcom.com>
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Date: Thu, 26 Jan 2017 10:39:50 -0800
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To: Tal Mizrahi <talmi@marvell.com>
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Cc: "detnet-dp-dt@ietf.org" <detnet-dp-dt@ietf.org>, Loa Andersson <loa@pi.nu>
Subject: Re: [Detnet-dp-dt] [EXT] Re: Data Plane Approach - Synchronization Traffic
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> On Jan 25, 2017, at 11:10 PM, Tal Mizrahi <talmi@marvell.com> wrote:
> 
> Hi Loa,
> 
> 
>>> - If the answer is yes: not sure replication and elimination makes sense for PTP.
>> 
>> Why is that?
> 
> In order for PTP to work well, PTP packets have to be consistently sent over the same path. If packets are intermittently sent through two different paths (with two different delays) the PTP slave will not be able to synchronize in a stable way.
> However, it *does* make sense for PTP to be sent through two different paths *without* elimination at the end. Such path redundancy allows the slave to always receive the sync information through both paths, which actually allows more robust synchronization than over a single path.
> 
> So path redundancy is good for PTP, but elimination - not so good. 

In a path redundancy case would the PTP messages on multiple paths be exact copies a single origin PTP message or different PTP messages?

- JOuni


> 
> Cheers,
> Tal.
> 
> 
>> -----Original Message-----
>> From: Loa Andersson [mailto:loa@pi.nu]
>> Sent: Thursday, January 26, 2017 9:01 AM
>> To: Tal Mizrahi; detnet-dp-dt@ietf.org
>> Subject: [EXT] Re: [Detnet-dp-dt] Data Plane Approach - Synchronization Traffic
>> 
>> External Email
>> 
>> ----------------------------------------------------------------------
>> Tal,
>> 
>> On 2017-01-26 14:44, Tal Mizrahi wrote:
>>> Hi,
>>> 
>>> I realize this is a bit off-topic, but one of the things I am wondering about is how
>> synchronization traffic (PTP) is forwarded in the context of the data plane
>> approaches we have been considering.
>>> Is PTP transported as a DETNET flow?
>>> - If the answer is no: does that mean we are assuming that synchronization is
>> achieved at a different layer, possibly requiring dedicated communication
>> between the customer and provider?
>>> - If the answer is yes: not sure replication and elimination makes sense for PTP.
>> 
>> Why is that?
>> 
>> /Loa
>>> 
>>> Will be happy to hear your thoughts, and apologies if this has already been
>> discussed elsewhere and I am not aware.
>>> 
>>> Cheers,
>>> Tal.
>>> _______________________________________________
>>> Detnet-dp-dt mailing list
>>> Detnet-dp-dt@ietf.org
>>> https://www.ietf.org/mailman/listinfo/detnet-dp-dt
>>> 
>> 
>> --
>> 
>> 
>> Loa Andersson                        email: loa@mail01.huawei.com
>> Senior MPLS Expert                          loa@pi.nu
>> Huawei Technologies (consultant)     phone: +46 739 81 21 64
> 
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