Real-Time Reporting Incorrectly

[willieb]

What causes the Max to be so high? This is a gig interface so 2.57G is not expected as possible. Also is it graphing Max instead of avg? If so how can we change it to avg to get a more usable graph? Thanks.

Edit: BTW I'm using Denika 7.0.

[jghidoni]

Hi Willieb,

Real-time reporting is polling the snmp values for in octets and out octets every second. These values are counters, ever increasing. Each second a response is received, it subtracts the previous snmp response value to get the difference. It is this difference which is plotted on the Real-time graph.

SNMP responses are not top priority for a device, so it may not always respond every second. However, the real-time graph will still subtract the previous response received (may have been 1 or more seconds passed), and graph the difference between the current response and the last response.

That is how you can get values greater than your max allowable bandwidth plotted on the Real-time graph, if it is reporting 2 or more seconds worth of data in a 1 second timeframe.

For example, 1 gig interface is at 90% utilization, so if it skips a second and reports 2 seconds of data, it will be reporting 1.8 G, which is more than the allowable 1 G bandwidth.

You can also see the pattern in the example you show. There are gaps, then spikes, indicating non-reporting seconds, then over-reporting seconds.

Does that answer your question sufficiently?

Again, because SNMP is not top priority to be handled by the device, if the device is very busy, it very well may not respond to the SNMP requests every second.

- Joanne

[willieb]

That does answer my question for why it's happening but it basically renders the graph useless for us. Is there any way to graph the average utilization? Thanks.

[jghidoni]

There is no configuration options for the Real-time graphing.

The standard Denika reports aren't giving you detailed enough data?

There is also a free tool available on our support site - STG - Realtime SNMP graphing utility. You need to know the MIB.

http://www.plixer.com/support/tools.php

- Joanne