General configuration parameters influence probe frequency, the delay metric type to monitor, and retention of the delay measurement last reported.
The probe frequency, configured using the interval command, defines the transmission rate of the test packet.
The delay command configures the delay metric (minimum, maximum, or average) that is used for comparison against any configured thresholds. This metric is the same for both types of measurement windows, the sample-window and aggregate-sample-window.
The unidirectional-measurement specifies the method used to compute the unidirectional delay. If the clock synchronization between nodal clocks used by the OAM timestamp function is not synchronized to near exact accuracy, the derived option must be used. Specifying this option calculates the unidirectional measurement using the roundtrip delay divided by two computation. If synchronization can meet near exact accuracy, the actual option can be used. Specifying this option calculates the forward delay using the forward direction timestamps, T2-T1 computation.
When the operational state of the link measurement test transitions to down, the OAM function instructs the routing engine to clear the last reported delay value at the expiration of the last-reported-delay-hold. A previously reported delay is considered valid for the duration of this period and is cleared if the timer reaches zero. If the operational state returns to up before the timer expires, no action is taken to clear the previous value. The counter is reset to the configured value, waiting for the next operational down event.
The operation state for the interface delay test is determined by administrative actions and system events. The administrative events that determine the operational state are:
administratively disabling the measurement template associated with the interface
administratively disabling the active IP protocol that is being used to generate the test packet under the config>router>interface>if-attribute>delay>dynamic-delay context
The resource issue system events that drive the operational state are:
unavailability of the UDP port
internal errors
The aging timer does not start a count to zero for failure conditions that do not affect the interface delay test operational state. The delay measurement last reported is maintained when conditions external to the interface delay test, such as fault conditions on the port, IP interface, routing changes, and so on, occur. If the last-reported-delay-timer is set to zero, previously reported delay values from that test are cleared when the operational state changes to down without any additional time.