3.2.5.1 Receiving an Ack Frame

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Upon receipt of an Ack frame, the mapper MUST first validate the Ack frame by verifying that all of the following statements are true:

  • The mapper did indeed solicit the response via an Emit frame, as tracked by the pended request state.

  • The Real Source Address field in the Base header of the Ack frame matches the MAC address of the destination responder in the Emit request.

  • The Sequence Number field in the Base header of the Ack frame matches that used in the Emit request.

Upon successful validation, the relevant Per-Responder Response timer MUST be stopped, and the sequence number for the affected responder MUST be incremented by one using ones-complement arithmetic (that is, it MUST advance from 0xFFFF to 0x0001 and skip 0x0000) for the next request with a nonzero sequence number.

If the Ack frame completes the last test that the application requests, the mapper MUST delete the old Pended request and indicate to the application that the network tests have been completed.