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:

 

ParameterDescription
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.

Example(s)


Related and Further Reading
 
Categories
 
Status

DRAFT

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