The (high 32 bits) value of
wfFrSwCctLocalSentDEFrames value at
wfFrSwUsageEndTimeStamp.
Note: Since wfFrSwCctLocalSentNonDEFrames
is a 32-bit COUNTER, this is really a counter
keeping track of number of times
wfFrSwCctLocalSentDEFrames has wrapped
around.