Hi all,

 

When viewing All Protocols > Throughput and sorting the Current column
under Data Descending (Top Talkers at top) I often see throughputs WAY
off from reality.  The bytes sent/rcvd counters are accurate enough - so
I'm curious why the Throughputs would be so far off?

 

I thought perhaps it had to do with netflow export timeouts and the test
xfers I was doing were too short.  So, using Iperf I sent a 500Kb/s udp
stream between two hosts for 5 minutes.  Iperf counters and Cisco
interface counters both agreed the stream was ~ 500Kb/s, yet nTop showed
everything from 20Kb/s near the beginning of the test to 1.7Mb/s near
the end of the test.  It was dead on at 500Kb/s a couple times - but why
such disparity?

 

Could it have to do with the refresh interval of the browser and the
netflow export timers?  How is the "Throughput" actually calculated?  I
guess I could tear into the code - but figured I'd throw it out to you
guys first.  I use netflow almost exclusively and it would be nice if
the throughput values were close.

 

 

My timers are as follows:

 nTop -r = 120.  I did this because I would be analyzing data on a page
and it kept refreshing and going to the top of page.  I'd scroll down to
look at some data and it would do this again.  VERY annoying!

 

 Netflow: Active flows = 60secs, Inactive = 10 secs.  These are the
lowest timeouts available.

 

Thanks!

 

Gary

 


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