Connected: An Internet Encyclopedia
4.3.3.8 Timestamp and Timestamp Reply

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4.3.3.8 Timestamp and Timestamp Reply

4.3.3.8 Timestamp and Timestamp Reply

A router MAY implement Timestamp and Timestamp Reply. If they are implemented then:

The preferred form for a timestamp value (the standard value) is milliseconds since midnight, Universal Time. However, it may be difficult to provide this value with millisecond resolution. For example, many systems use clocks that update only at line frequency, 50 or 60 times per second. Therefore, some latitude is allowed in a standard value:

  1. A standard value MUST be updated at least 16 times per second (i.e., at most the six low-order bits of the value may be undefined).

  2. The accuracy of a standard value MUST approximate that of operator-set CPU clocks, i.e., correct within a few minutes.

IMPLEMENTATION

To meet the second condition, a router may need to query some time server when the router is booted or restarted. It is recommended that the UDP Time Server Protocol be used for this purpose. A more advanced implementation would use the Network Time Protocol (NTP) to achieve nearly millisecond clock synchronization; however, this is not required.


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Connected: An Internet Encyclopedia
4.3.3.8 Timestamp and Timestamp Reply