This counts received frames that either exceeded the 2K-byte maximum frame length or overflowed the modem's HDLC receive buffer. This points to either an oversized-frame problem upstream, such as jumbo frames being sent toward a modem that can't handle them, or the HDLC buffer failing to keep pace with the incoming data rate on the satellite link. For example, enabling jumbo frames on a LAN switch feeding this modem could cause this counter to start incrementing where it was previously zero.