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Cristian's Algorithm Assignment Example

Compensate for delays

Note times:

  • request sent: T0
  • reply received: T1

Assume network delays are symmetric

Cristian's Algorithm Example 1

Client sets time to:

Cristian's Algorithm Example 2

Cristian’s algorithm: example

  • Send request at 5:08:15.100 (T0)
  • Receive response at 5:08:15.900 (T1)

    • Response contains 5:09:25.300 (Tserver)

  • Elapsed time is T1-T0

    5:08:15.900 - 5:08:15.100 = 800 msec

  • Best guess: timestamp was generated 400 msec ago
  • Set time to Tserver + elapsed time

    5:09:25.300 + 400 = 5:09.25.700

    If best-case message time = 200 msec
Cristian's Algorithm Example 3
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