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

Christopher J. Holland msnews at microsoft.com
Thu Jul 31 11:24:21 UTC 2003


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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