This is the total count of frames received over the satellite interface at the HDLC layer. It is the raw denominator an admin uses alongside the various Rx error counters, such as CRC, overrun, and bad-address counts, to compute an actual error rate rather than reacting to raw error counts that are meaningless without a traffic-volume baseline. For example, 50 HDLC CRC errors out of 10,000,000 received frames is a negligible 0.0005% error rate, while the same 50 errors out of 500 frames would be alarming.