Technical Documentation

jnxRpmResultsSampleTable

The jnxRpmResultsSampleTable provides you measurements from the latest individual RPM probe samples. Each jnxRpmResultsSampleEntry has the objects listed in Table 1.

Note: jnxRpmResultsSampleTable does not maintain entries for unsuccessful probes.

Table 1: jnxRpmResultsSampleTable

Object

Object Identifier

Description

jnxRpmResSampleType

jnxRpmResultsSampleEntry 1

The measurement type for the particular jnxRpmResultsSampleEntry.

jnxRpmResSampleValue

jnxRpmResultsSampleEntry 2

The measurement for the entry.

jnxRpmResSampleTsType

jnxRpmResultsSampleEntry 3

The type of timestamp used to obtain the measurement.

jnxRpmResSampleDate

jnxRpmResultsSampleEntry 4

Date and time at which the measurement was obtained.

For information about JnxRpmMeasurementType, see the following section:

JnxRpmMeasurementType

Different types of measurements can be made for each probe. Table 2 lists the measurement types used in jnxRpm.mib.

Table 2: JnxRpmMeasurementType

Measurement Type

Description

roundTripTime

The delay between the transmission of a probe and the arrival of its response.

rttJitter

The difference between the current round trip time measurement and the previous one.

rttInterarrivalJitter

An estimate of the statistical variance of a packet’s inter-arrival time defined in RFC 1889 as:

J=J+(|D(i-1,i)|-J)/16

where J is the inter-arrival jitter and D (i-1, i) is the egressJitter measurement.

egress

The delay between the transmission of a probe and its arrival at the destination.

egressJitter

The difference between the current egress delay and the previous measurement.

egressInterarrivalJitter

An estimate of the statistical variance of a packet’s inter-arrival time. Defined in RFC 1889 as:

J=J+(|D(i-1,i)|-J)/16

where J is the inter-arrival jitter and D (i-1, i) is the egressJitter measurement

ingress

The delay between the transmission of a probe response and its arrival at the destination.

ingressJitter

The difference between the current ingress delay and the previous measurement.

ingressInterarrivalJitter

An estimate of the statistical variance of a packet’s interarrival time. Defined in RFC1889 as:

J=J+(|D(i-1,i)|-J)/16

Where J is the interarrival jitter and D (i-1, i) is the current ingressjitter measurement.

Not all types of measurements are performed for every probe. For example, the jitter measurements are available only for those RPM entries that use hardware timestamps on both client and server. Similarly, the ingress and egress measurements are available only for those probe types that measure one-way delays or where hardware timestamps are used (for this, the one-way-hardware timestamp knob must be enabled). However, in the cases discussed above, if the one-way delay is greater than the round-trip time, the corresponding entries are not stored.

Note: To avoid possible variations in one-way jitter measurements and calculations due to clock synchronization issues, one-way jitter measurements are performed only on samples that are less than 10 seconds apart.


Published: 2010-04-27