This read-only Counter64 counts frames — not bytes — received on this PM instance that the switch accepted. Pairing it with the accepted-bytes counter on the same instance lets an admin derive the average accepted frame size, which flags whether the link is carrying many small control/voice frames or fewer large bulk-data frames; because it is drawn from the lifetime bin, which keeps accumulating until an operator explicitly clears it, a sudden plateau on an otherwise busy instance is itself a signal — most likely that someone cleared the stats rather than that traffic actually stopped. On EVC 105 (E-Line, 100 Mbps CIR/1 Gbps EIR), this might read 870,000 frames over the 95 days since the counters were last cleared, which an admin would cross-check against the matching byte counter to see if average frame size looks normal for that service.