2.2.4.12 Flat Upper-Level Header Format

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A responder sends a Flat frame to a mapper in response to the following:

  • An Emit frame that has a nonzero sequence number and requires more charges than the responder has. The Flat frame tells the mapper to retry the Emit request, preceded by a fixed count of Charge frames to build up the needed charge.

  • A Charge frame that has a nonzero sequence number, which effectively forces the responder to report its current charge count.

Such a charge frame MUST contain enough padding to satisfy the charge required for the responder to send the Flat Frame response.

The Flat frame following a Base header MUST have the following format.


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Current_Transmit_Credit_in_Bytes

CTC_in_Packets

Current_Transmit_Credit_in_Bytes (4 bytes): (CTC) This field specifies the value of the CTC byte counter at the responder, in network byte order.

CTC_in_Packets (1 byte): This field specifies the value of the CTC packet counter at the responder, in network byte order.