[ntp:questions] Re: Question about RFC-2030 SNTP Version4
David L. Mills
mills at udel.edu
Thu Jul 31 15:11:15 UTC 2003
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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