Description: The port buffer congestion threshold provides an early warning to the switch that the port is about to exhaust all its guaranteed buffers, leading to congestion. This threshold is expressed as a percentage of the port's total guaranteed buffer depth. Once this threshold has been crossed, the switch begins colliding with frames received on the port for a fixed period of time. After this time has expired, the switch determines whether the port's buffer congestion has been alleviated. If this situation has not changed, the switch resumes this congestion control algorithm on the port.