SLA Measurements

The following metrics are measured as part of this IP SLA jitter functionality.

One way jitter

One way jitter is defined as the time difference between inter-packets transmit time and inter-packets arrival time in a given direction. This is measured in both the Initiator to Responder direction (referred to as SD jitter) as well as the Responder to initiator direction (referred to as DS jitter).

Ideally, the jitter in both directions should be 0. A positive value of jitter is bad for VOIP and higher values of jitter will mean poor conversation quality. This is explained in the illustration below:

One way delay

One way delay is defined as the time difference between the Initiator transmitting the frame and the Responder receiving the frame. This requires the Initiator and the Responder to be time synchronized with the same clock server. This is explained in the illustration below:

Round trip time

RTT is measured at the initiator on a per packet basis and is as illustrated below: