PM6344 datasheet(223/256 Pages) PMC

223 / 256 page

STANDARD PRODUCT

PMC-Sierra, Inc.

PM6344 EQUAD

PMC-951013

ISSUE 5

QUADRUPLE E1 FRAMER

210

13.6 Using the Performance Monitor Counter Values

All PMON block event counters are of sufficient length so that the probability of

counter saturation over a one second interval at a 10-3 BER is less than 0.001%.

The odds of any one of the counters saturating during a one second sampling

interval go up as the BER increases. At some point, the probability of counter

saturation reaches 50%. This point varies, depending upon the framing format

and the type of event being counted. The BER at which the probability of counter

saturation reaches 50% is shown below for various counters:

Table 7

Counter

BER

LCV

4.0 x 10-3

FER

4.0 x 10-3

CRCE

cannot saturate

FEBE

cannot saturate

Below these 50% points, the relationship between the BER and the counter

event count (averaged over many one second samples) is essentially linear.

Above the 50% point, the relationship between BER and the average counter

event count is highly non-linear due to the likelihood of counter saturation.

Figure 32-Figure 34 show this relationship for various counters and framing

formats. These graphs can be used to determine the BER, given the average

event count. In general, if the BER is above 10-3, the average counter event

count cannot be used to determine the BER without considering the statistical

effect of occasional counter saturation.

PM6344 Datasheet(PDF) 223 Page - PMC-Sierra, Inc