Re: [TICTOC] PTP Enterprise Profile draft

["Rodrigues, Silvana" <[e-mail]>]

Doug,

Thanks for the draft. I also agree with Stefano's comment and I have a few additional comments.

Item 3 and 4 from Stefano's email below, I think that there is a need to add some warning in the text, as the way it is written, it does look like that  if this profile is implemented over any network the 1us requirement will be met.

Section 10, it states that slave may use an Acceptable Master list. How this will work when transparent clocks are used and the source address in the TCs are changed to the TC source address? The Slave will no longer have the source address of the masters.

Section 12, it states that Unicast negotiation is forbidden. How the packet rate will be negotiated between the master and slave for Unicast Mode?

Thanks,

Silvana


From: [e-mail] [mailto:[e-mail]] On Behalf Of Stefano Ruffini
Sent: Monday, March 04, 2013 11:20 AM
To: Doug Arnold; [e-mail]
Subject: Re: [TICTOC] PTP Enterprise Profile draft

Hi Doug,


thanks for your draft .


There are a few points that I think would need some clarification.

1) As also mentioned at last tictoc meeting, there is a risk of multiplication of profiles.
It is not fully clear in the Introduction what is so specific to enterprise networks to requiring the definition of a specific profile.



2) the proposed profile would support a combinations of various options (e.g. various modes defined in section 6) but the task of a profile should normally also be to minimize the number of IEEE1588 options. Are all these options really required ?


3) section 4 indicates a target requirement of 1 us : is there a reference for that?

4) It should be noted that the performance (e.g. 1 us) can not be guaranteed by a profile as such.
Other aspects, such as network reference model, clock characteristics, also have to be defined in order to provide some guarantee on the achievable performance.
How are these planned to be addressed? Will it make reference to ITU-T recommendations?


5) Concerning the "Hybrid" and "Unicast" mode in section 6.3 (see also remark from Laurent on the confusing terminology used), in case of "partial support" , the potential risk of adiditonal asymmetries should be mentioned (see also Appendix I in G.8265.1) .
This is not an issue in case of frequency sync but it is in case of time sync.


Best Regards
Stefano

________________________________
From: [e-mail]<mailto:[e-mail]> [mailto:[e-mail]] On Behalf Of Doug Arnold
Sent: lunedì 25 febbraio 2013 22.52
To: [e-mail]<mailto:[e-mail]>
Subject: [TICTOC] PTP Enterprise Profile draft
Here is a first cut at a draft of a PTP profile foe enterprise networks.  Any feedback/suggestions would be much appreciated.

I enclose both a MS Word version and a pure text version, since I used the Joe Touch's template.

//Doug