Spirent SmartBits System, Reference Manual

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Chapter 11: ATM Cards
ATM Line Parameters
162 SmartBits System Reference
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HEC Coset :
– Checked – Exclusively ORs (Boolean operation) the result of the header CRC
with the HEC coset 0x55. Most ATM devices require this feature to be on.
– Unchecked – Uses the header CRC without modification.
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Cell Scrambling :
– Checked – Scrambles the payload content of the cells using the self-synchronized
scrambler to facilitate cell delineation. Most ATM devices require this feature to
be on.
– Unchecked – Does not scramble the cell payloads.
•
Idle Cell Header . Specify the header contents ( 4-bytes in hexadecimal) of the ATM
idle cell payload (the first four bytes of the header) that is transmitted when no data
cells are being transmitted. SmartWindow calculates the HEC byte for the specified
header internally. For the AT-9622 OC-12c SmartCard, enter only idle cells with the
VPI/VCI fields set to zeroes.