3.6.5.1 Timer Events on PDC

When the PDC timer expires, the PDC MUST prepare the announcement message (as specified in section 2.2.1.5.1) using the current database state, and send the message to BDCs that need synchronization. A BDC needs database synchronization if one of the following conditions is true:

  • The announcement is forced as a result of administrative action.

    The announcement can be forced if this is a new BDC configured in the domain.

  • The BDC database serial number is less than the PDC database serial number for the corresponding database as indicated by an AbstractBdcDatabaseSerialNumbers element corresponding to the BDC and the database. To prevent sending messages to slow or unreachable BDCs, this condition can be augmented to require that the BDC finishes processing the previous announcement (if any), or it is timed out before the PDC sends a new announcement message.

  • A separate timer is used on the PDC to time out announcements sent to the BDCs. A BDC is deemed as processing the announcement request until it finishes the processing by completing a synchronization request as defined in the following sections. During that time, no additional announcements are sent to the BDC. If a BDC doesn't respond with a synchronization request within the time-out period as set by the timer, the announcement is deemed as timed out.

  • More than AbstractMaximumPulse seconds passed since the BDC was sent the previous announcement message.

To reduce the load on the PDC from synchronization requests following the PDC announcement, the PDC sends messages only if the current value of AbstractPulseConcurrency is less than a certain value defined as a configuration setting.

The PDC resets its timer to expire in the AbstractPulse seconds.

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