This counter tracks how many keyed HMAC calculation requests the accelerators received due to this specific security protocol's operation, counted since the last reboot. HMAC calculations underpin per-packet integrity checking, so this counter's rate for a given protocol row tells an admin how much of the accelerator's integrity-checking workload is attributable to that specific protocol versus others sharing the hardware. If a device runs both IPsec and SSL VPN, and the IPsec protocol row shows far more HMAC requests than the SSL row, that indicates the IPsec traffic is contributing more to the integrity-checking overhead on the shared accelerator.