2 Replies Latest reply: Feb 2, 2012 1:27 PM by Ralphr RSS

Throughput on 1 Gig Link Greater Than 1 Gig

Ralphr

Looking to accurately explain to management why NPM occasionally shows the throughput of a busy 1 Gig link as more than 1 Gig, just a little more but more.  Believe I have eliminated a possible cause as being an issue with counter rollover by changing to 64 bit counters and decreasing the polling rate to every minute.  Still had the issue.  Thought that it might be due to the calculation being based on buffered traffic as opposed to actual bytes on the wire.  Assume thats not it (these are Cisco router interfaces) as I see this over subscription issue on the both the RCV side and the TX side and I do not see corresponding discards on the TX side.  So I'm left with that this is simply not that exact of a calculation.  So that if I set the polling rate to 60 seconds (for ease of explanation) but the actual time delta between inOctets GET 1 and inOctets GET 2 is really 61 seconds or 60.5 seconds but NPM still uses 60 seconds to do the math then that would produce the over throughput numbers I am seeing occasionally.  It's either that or I am still missing something .  Any enlightenment would be appreciated.