A read-only counter that increments every time the repeater port automatically isolates itself due to false carrier events, per the 802.3 carrier integrity state machine's transition from False Carrier to Link Unstable. A rapidly climbing count signals a flaky physical link or bad NIC/cable causing the repeater to keep isolating the port to protect the rest of the collision domain, which admins use to pinpoint failing cabling or hardware. If this counter jumps from 5 to 50 within an hour on port 8, that is a strong indication the device connected there has a failing transceiver or cable.