Re: [ippm] Magnus Westerlund's Discuss on draft-ietf-ippm-stamp-07: (with DISCUSS and COMMENT)

[Magnus Westerlund <[e-mail]>]

Hi Henrik,

On Wed, 2019-09-11 at 10:30 +0200, Henrik Nydell wrote:
> See below for PTP/NTP comment
> 
> On Wed, Sep 11, 2019 at 9:53 AM Magnus Westerlund <
> [e-mail]> wrote:
> > 
> > On Tue, 2019-09-10 at 12:43 -0700, Greg Mirsky wrote:
> > 
> > > >         3.  Section 4.1.1.:
> > > >         Timestamp is eight octets long field.  STAMP node MUST
> > > > support
> > > >       Network Time Protocol (NTP) version 4 64-bit timestamp
> > format
> > > >       [RFC5905], the format used in [RFC5357].  STAMP node MAY
> > > > support
> > > >       IEEE 1588v2 Precision Time Protocol truncated 64-bit
> > > > timestamp
> > > >       format [IEEE.1588.2008], the format used in [RFC8186].
> > > > 
> > > >         Is the clock source here something that may be relevant
> > or
> > > > simply
> > > >         information the management functions should capture. I
> > > > think there is a
> > > >         similar issue to that of RTP faced when it comes to
> > > > understand what the
> > > >         timestamp actually represent and thus be used
> > correctly.
> > > > RTP clock
> > > >         source specification is RFC 7273
> > > >         (https://datatracker.ietf.org/doc/rfc7273/)
> > > 
> > > GIM>> NTP and PTP encodings have a different interpretation of
> > the
> > > Fraction field of the Timestamp field. In my experience, PTP
> > format
> > > is native for the data plane, while NTP is more used at the
> > control
> > > plane. Original extension to TWAMP has been described in RFC
> > 8186.
> > 
> > I think you missunderstood. When I talk about clock source, I am
> > actually referring to identifying the particular clock that the
> > node
> > use to derive the included timestamp from. 
> > 
> > And likely this is a moot point in this document where the clock
> > source
> > information belongs in the management layer, e.g. in the YANG data
> > model. 
> 
>  
> In section 4.1.1 of draft-ietf-ippm-stamp there is a definition of
> the Z-bit in the error correction field that denotes if the clock
> source is NTP or PTP
>  

Yes, to be clear I have no issue with if the format is NTP or PTP. That
was not my comment. It was a comment if the protocol should identify
which particular NTP or PTP server the node is using. For example for a
node on my network having NTP based clock it matters if that NTP server
is sth1.ntp.se which is a stratum 1 server distributing certified
swedish time, or if I use europe.pool.ntp.org where I would use any NTP
server part of the pool indicating that they are in europe. 


However, I am convinced that information is of interest the information
should be in the management layer. 


Cheers

Magnus Westerlund 


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