A HighUtilization fault for a network adapter results in a PerformanceException for the affected system or VLAN. IP Performance Manager detects a HighUtilization fault when the current utilization is greater than the UtilizationThreshold configured for this network adapter.

Port and Interface objects represent the connections between switches and routers, respectively, and the wires or other physical media that lead to other systems. Two fundamental properties that describe a Port or Interface are its speed and its duplex mode:

  • The speed of a port or interface is the maximum rate at which it can transport information. Speed is usually expressed in bits per second (bps).

  • The duplex mode for a port or interface controls whether data transmission is full-duplex or half-duplex. With full-duplex transmission, both ends of a network connection can send data simultaneously. With half-duplex transmission, only one end of a network connection can send data at a time. If the duplex mode is unspecified, IP Performance Manager cannot monitor the adapter for HighUtilization faults. “Duplex-mode discovery for Network adapters” on page 79 provides more information about how IP Performance Manager determines duplex mode for a port or interface.

    The current utilization of a port or interface is the ratio, expressed as a percentage, of the total number of bits sent over some interval over the total number of bits that could have been sent in that same interval. A value of 100% means that, had more traffic arrived in that period, some would have been dropped due to lack of capacity.

    As an example, suppose a port with a speed of 100,000 bps sent 450,000 bits and received 400,000 bits in the last 10 seconds. To compute the current utilization, IP Performance Manager first needs to know whether the system is full- or half-duplex:

  • If the system is full-duplex, the limiting factor is the more heavily loaded (outgoing or incoming) wire. For a full-duplex, 100,000 bps system, each wire can carry 1,000,000 bits in 10 seconds. The outgoing wire carried 450,000 bits, or 45 percent of the theoretical capacity; the incoming wire carried 400,000 bits, or 40 percent of capacity. IP Performance Manager defines the current utilization as 45 percent, the higher percentage.

  • If the system is half-duplex, the total traffic has to go over a single wire. In this case, a total of 850,000 bits moved over the wire, which could have carried 1,000,000. Hence, the current utilization is 85 percent.

    IP Performance Manager reports the HighUtilization fault when the current utilization exceeds the UtilizationThreshold configured for the port or interface.

    This threshold is contained in both the Generic Interface/Port Performance setting and the Ethernet Interface/Port Performance setting.