Monitoring Cisco TenGigabit Interfaces

Nerdbebo

Hello!

 We recently upgraded our uplinks to 10GB, I went to make the changed in IPMonitor only to discover we were now pushing less than 100Mb of traffic, when in fact PRTG and the 1 minute interface average on the router show we are pushing around 1GB of traffic across these links. It almost seems that IPMonitor is assuming these interfaces are 100Mbit and changing the monitors.

 From IP Monitor:

Traffic In: 3.9235 MB/s

Traffic Out: 4.4396 MB/s

 

From the Cisco:

  1 minute input rate 256716000 bits/sec, 135813 packets/sec
  1 minute output rate 653518000 bits/sec, 120882 packets/sec

 Ideas?

Fodome

Hi Nerdbebo,

ipMonitor uses 2 SNMP OIDs to gather this information; ifInOctets and ifOutOctets. 
These OIDs provide the number of octets (or bytes) transfered since boot.
In order to calculate the amount of bytes transfered, one would perform a delta between the sum of the current values and the sum of the last values gathered and then divide the result by the number of seconds between the time the two values were gathered.

The problem with this is that the values retrieved over SNMP are limted to 4294967296.  This means that when 4 Gigs has been transfered, the counter is reset to 0.  This can pose a problem when calcuating deltas and may result in what you are seeing.

In order to reduce these low numbers and increase the accuracy of what is being reported within ipMonitor, I recommend setting the Monitor to poll more often such as every 30 to 60 seconds.

Let me know if this helps.

Sincerely,

Chris Foley - SolarWinds - Support Specialist
Support:  866.530.8040  |  Fax: 512.857.0125
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