3.1.4.3 Higher Layer Initiates Sending of Data

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This event is triggered when the higher layer initiates the sending of data over an SMP session.

Any packet that is sent MUST NOT contain a SEQNUM value higher than the value of the HighWaterForSend variable.

If a DATA packet cannot be sent to its peer because the value of the SeqNumForSend variable of the Session object is equal to the value of the HighWaterForSend variable of the Session object, the SMP layer performs one of the following two actions:

  • Buffer the DATA packet in a local buffer and send it at a later time according to the flow control algorithm described in section 3.1.5.2.

  • Block the higher layer until the DATA packet is sent according to the flow control algorithm described in section 3.1.5.2.

If the value of SeqNumForSend is less than that of HighWaterForSend, the SMP layer of the sender sends the DATA packet according to the flow control algorithm described in section 3.1.5.2.