[ntp:questions] Re: Question about RFC-2030 SNTP Version4

Christopher J. Holland msnews at microsoft.com
Fri Aug 1 01:19:44 UTC 2003


Hi,

Thanks, but that isn't what I was asking. You already pointed it out.
I was just lucky to join the list when you did post it.

I am trying to relate T1,T2,T3 & T4 to the Packet Structure.

***** Is this the correct way? *******************************
Originate Timestamp T1 = (Packet) Reference Timestamp
Receive Timestamp T2 = (Packet) Originate Timestamp
Transmit Timestamp T3 = (Packet) Receive Timestamp
Destination Timestamp T4 = (Packet) Transmit Timestamp

 ***** Is this the correct way? *******************************
Originate Timestamp T1 = (Packet) Originate Timestamp
Receive Timestamp T2 = (Packet) Receive Timestamp
Transmit Timestamp T3 = (Packet) Transmit Timestamp
Destination Timestamp T4 = (Then where do I get this value? is it the
Reference Timestamp?)
**********************************************


> >       Timestamp Name          ID   When Generated
> >       ------------------------------------------------------------
> >       Originate Timestamp     T1   time request sent by client
> >       Receive Timestamp       T2   time request received by server
> >       Transmit Timestamp      T3   time reply sent by server
> >       Destination Timestamp   T4   time reply received by client
> >
> >    The roundtrip delay d and local clock offset t are defined as
> >
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       |                                                               |
> >       |                   Reference Timestamp (64)                    |
> >       |                                                               |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       |                                                               |
> >       |                   Originate Timestamp (64)                    |
> >       |                                                               |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       |                                                               |
> >       |                    Receive Timestamp (64)                     |
> >       |                                                               |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       |                                                               |
> >       |                    Transmit Timestamp (64)                    |
> >       |                                                               |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>

TIA,
Thanks,
"David L. Mills" <mills at udel.edu> wrote in message
news:bgbbil$be4$1 at dewey.udel.edu...
> Christopher,
>
> Please take a number. You are somewhere in the list of thirty-odd folks
> who have found and reported that typo
>
>        d = (T4 - T1) - (T3 - T2)     t = ((T2 - T1) + (T3 - T4)) / 2.
> (Correct Formula)
>
> The correction is on file at the IETF. A draft update to RFC-2030 with
> this correction and much new material is in review.
>
> Dave
>
> Christopher J. Holland wrote:
>
> > Hi,
> >
> > I managed to decipher the 32 Bit Time to YYYY/MM/DD/HH//MM/SS format.
> > Is there an RFC to tell you how to do that?
> > Now, I am trying to figure out how to calculate Round Trip delay and
Offset.
> > I'm not sure which fields are which?
> > Good thing I popped on this list at this time. I still had the old
> > conversion formula!
> >
> >
> > Does
> > Originate Timestamp T1 = (Packet) Reference Timestamp
> > Receive Timestamp T2 = (Packet) Originate Timestamp
> > Transmit Timestamp T3 = (Packet) Receive Timestamp
> > Destination Timestamp T4 = (Packet) Transmit Timestamp
> >
> > or does
> > Originate Timestamp T1 = (Packet) Originate Timestamp
> > Receive Timestamp T2 = (Packet) Receive Timestamp
> > Transmit Timestamp T3 = (Packet) Transmit Timestamp
> > Destination Timestamp T4 = (Then where do I get this value? is it the
> > Reference Timestamp?)
> >
> >
> >       Timestamp Name          ID   When Generated
> >       ------------------------------------------------------------
> >       Originate Timestamp     T1   time request sent by client
> >       Receive Timestamp       T2   time request received by server
> >       Transmit Timestamp      T3   time reply sent by server
> >       Destination Timestamp   T4   time reply received by client
> >
> >    The roundtrip delay d and local clock offset t are defined as
> >
> >       d = (T4 - T1) - (T2 - T3)     t = ((T2 - T1) + (T3 - T4)) / 2.
(Wrong
> > Formula)
> >       d = (T4 - T1) - (T3 - T2)     t = ((T2 - T1) + (T3 - T4)) / 2.
> > (Correct Formula)
> >
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       |                                                               |
> >       |                   Reference Timestamp (64)                    |
> >       |                                                               |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       |                                                               |
> >       |                   Originate Timestamp (64)                    |
> >       |                                                               |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       |                                                               |
> >       |                    Receive Timestamp (64)                     |
> >       |                                                               |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       |                                                               |
> >       |                    Transmit Timestamp (64)                    |
> >       |                                                               |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >
> > Thanks for your help
> >
> >
> >
>





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