This read-only Counter32 counts Backward RM cells received from the network on this Frame Relay channel, the return-path cells that carry congestion feedback back to the sending side. An admin uses it to verify that congestion signaling is flowing on the connection, since backward RM cells are what let the source throttle its rate in response to network conditions. A sudden drop to zero on a connection that previously showed steady counts could indicate the feedback loop has broken, risking uncontrolled sending rates.