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Re: [TICTOC] Enterprise profile update

Douglas Arnold <doug.arnold2@gmail.com> Mon, 07 April 2014 20:48 UTC

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Date: Mon, 07 Apr 2014 22:48:35 +0200
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From: Douglas Arnold <doug.arnold2@gmail.com>
To: Kevin Gross <kevin.gross@avanw.com>
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Subject: Re: [TICTOC] Enterprise profile update
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Hi Kevin,

This is a good point and ma require some warning text be added to the draft

Doug


On Mon, Apr 7, 2014 at 7:59 AM, Kevin Gross <kevin.gross@avanw.com> wrote:

> I can't remember if this was discussed in TICTOCK yet. Apologies if I'm
> bringing up a settled point.
>
> I appreciate the scalability of unicast delay request/response but I want
> to make sure everyone is aware of a hazard with hybrid mode. On some
> networks, unicasts and multicasts are delivered through separate network
> paths. On these networks, half the round trip delay of a delay
> request/response unicast exchange will not be a good estimate of sync
> multicast propagation time.
>
> It may be best to leave a multicast delay request/response option for
> devices that need higher accuracy or want to have the option to compare
> unicast and multicast delay request/response performance to determine
> whether hybrid mode is viable on the network they are connected through.
>
> Kevin Gross - AVA Networks
>
>
> On Sat, Apr 5, 2014 at 7:37 AM, Richard Cochran <richardcochran@gmail.com>wrote:
>
>> On Sat, Apr 05, 2014 at 01:20:35PM +0200, Richard Cochran wrote:
>> > Doug,
>> >
>> > On Wed, Mar 12, 2014 at 12:41:33PM -0700, Douglas Arnold wrote:
>> >
>> > > 1. Elimination of the Unicast only and Multicast only modes of
>> operation.
>> > >  The only mode of operation is the hybrid multicast/unicast mode.  In
>> this
>> > > mode the master sends sync and announce as multicast, and it responds
>> to
>> > > delay request messages "in kind".  In other words a delay response is
>> > > unicast if the delay requests is unicast, and multicast if the delay
>> > > requests is multicast.
>> >
>> > Nice. This idea makes way more sense than the unicast option in 1588,
>> > IMHO.
>>
>> On second thought, why doesn't this profile simply say that slaves may
>> use 1588 section 16.1 to negotiate unicast Delay_Resp messages?
>>
>> As is, this profile mandates behavior WRT unicast that isn't really
>> allowed by 1588, unless you say that it falls under the very vague and
>> open ended 7.3.1 clause.
>>
>> I would prefer the common sense unicast handling in your profile, but
>> unfortunately 1588 already specifies something else.
>>
>> Thanks
>> Richard
>>
>> _______________________________________________
>> TICTOC mailing list
>> TICTOC@ietf.org
>> https://www.ietf.org/mailman/listinfo/tictoc
>>
>
>


-- 
Doug

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