Inter-Frame Delay Variation (IFDV) is the difference between the one-way delay of a pair of selected Service Frames of the same Class of Service (CoS). This definition is borrowed from RFC 3393 where IP packet delay variation is defined. For a particular Class of Service Identifier and an ordered pair of UNIs in the EVC, IFDV Performance is applicable to Qualified Service Frames.

MEF 10 and 10.1 refer to Inter-Frame Delay Variation as “Frame Delay Variation”.

The term "Jitter" is not an appropriate term to be substituted for Frame Delay Variation

Computing IFDV

The Inter-Frame Delay Variation Performance is defined as the P-percentile of the absolute values of the difference between the Frame Delays of all Qualified Service Frame pairs that satisfy the following conditions:

The difference in the arrival times of the first bit of each Service Frame at the ingress UNI was exactly some (small) time value Δ .

The concept is depicted below (click to enlarge):


Assuming that for a given EVC and for a specific CoS ID, ETH-DM procedure is executed every 1 second (D t1 second), the absolute value difference between 2 consecutive readings is the measured value. At the end of the time interval T , a percentile is calculated and is compared with the objective. For the SLS, an Inter-Frame Delay Variation metric MUST specify a set of parameters and an objective. The parameters and objective for an Inter-Frame Delay Variation Performance metric are given in the following table:


T The interval
S Subset of the ordered UNI pairs of the EVC
P Inter-Frame Delay Variation Performance percentile
D t The separation between frame pairs for which Inter-Frame Delay Variation Performance is defined
Inter-Frame Delay Variation Performance Objective


The computation method above is applicable for a single ordered pair of UNIs. For a set S of ordered pairs, the IFDV is computed as the maximum of the individual measurements for each pair.


Related and Further Reading


Source(s) and Reference(s)
Section 6.9.4 of MEF 10.2 |