Using the Detail Chart only
The longest time frame that can be analyzed with the Detail Chart method is 15 minutes. You may be better off using the Microburst Analysis tab instead.
Tip! Microburst analysis is easier to comprehend using bars instead of lines on the Detail Chart. Choose Settings > Detailed Chart and change the appearance to 2D Columns. Depending on your preferences, at times you may also wish to change the Y-axis scale to 100 when you are viewing the chart as Percent of duration Intervals with Microbursts.
Note: When you change between the Percent and Number charts, the bars may not appear to change. If you look closely, you will notice that the numbers on the vertical axis change as does the title of the chart.
To enable microburst analysis and define what on your network qualifies as a microburst:
1. On the Home tab, in the Capture group, click GigaStor.
2. Click the Screen resolution box, which opens the Microburst Analysis options.
3. Select Enable Microburst Analysis and choose your settings. When you make changes to these options, the Detail Chart changes. Sometimes it is a very subtle change. All of these options are interrelated. By changing any one of these settings, you change what is determined to be a microburst. When that changes, the graphs change. Change only one option at a time, then view your changes.
Screen resolution (Interval/Total Time): The screen resolution is two numbers that define the length of time shown in the Detail Chart. The first number is the interval length, which when looking at a bar chart, is each bar. The second number is the total time of all of the intervals on the chart, although if an interval does not have any bursts the interval will not have a bar. The interval is used along with Duration to determine how many chunks of time are theoretically possible. See Table 38 for examples of how changing the interval may affect the Detail Chart.
Duration: The duration is length of time over which the burst is calculated. It must contain two or more packets (or partial packets) to be counted as a microburst. A single packet filling an entire duration interval does not count as a microburst. The shorter the time frame, the more bursts you may have because the length of time necessary to meet the threshold is shorter. Conversely, as you increase the length of time required for traffic to be considered a burst, fewer bursts will meet the duration threshold. This is why counts may change as you increase or decrease the duration. More of less traffic meets the duration threshold to be considered a microburst. See Table 38 for examples of how changing the duration may affect the Detail Chart.
Utilization threshold: The utilization threshold is the percent of your capture card speed that must be met before a microburst can be determined to have occurred. The lowest threshold allowed is 10%. The highest threshold is 100%, although it is extremely rare that 100% is ever achieved. Ninety-nine percent utilization is not uncommon though. See Table 38 for examples of how changing the Utilization threshold may affect the Detail Chart.
Full Duplex / DTE / DCE: Determines how the utilization threshold is calculated and what information is shown in the Detail Chart. These options are only available when the probe instance you are using is attached to a capture card. We do not recommend attaching passive probe instances to the capture card, so these options may not be available to you. In this case, your settings are Full Duplex + DTE + DCE are not available and cannot be changed.
Full Duplex + DTE + DCE: Each port on the capture card is considered independently from all others. The traffic is never combined between ports to meet a threshold. If you have a 4-port 1 Gb capture card, you have four independent 1 Gb connections.
A microburst is counted when the utilization on any one of the ports exceeds the utilization threshold, but only on that port. The threshold does not need to be met on all ports — just on one or more of them.
Full Duplex + DTE: Calculates and displays microbursts only on DTE ports. The DTE ports on the capture card are the even numbered ports (2, 4, 6, 8).
Full Duplex + DCE: Same as Full Duplex + DTE, except for DCE links. The DCE ports are the odd numbered ports (1, 3, 5, 7).
None selected: When no options are selected, the ports are combined to create the maximum utilization threshold. If you have a 4-port 1 Gb capture card, you have one connection with a 4 Gb maximum utilization. (This is the opposite of Full Duplex + DTE + DCE where you have four independent 1 Gb connections.) For this reason, you will likely see fewer microbursts than when any of the Full Duplex options are selected because the utilization threshold is higher.
Note: The Data type option is unavailable when doing Microburst analysis because Microburst analysis shows the number of times or percentage of time when a microburst occurs within a duration and utilization threshold. Because the charts show only microbursts and no other type of information, you cannot choose to show bytes, bits or packets for data type.
Percent of duration intervals with microbursts: The Detail Chart shows bursts as a percentage. It uses four variables to determine the percentage. Each bar (assuming your chart is configured to show bars instead of lines) represents one interval. Within each slice are smaller chunks of time, which are the durations (although they are not visible on the Detail Chart). The percentage is calculated by:
1
Screen resolution interval
=
Maximum number of intervals
Duration
2
Number of duration intervals with microbursts
=
Percent of interval durations with microbursts
Maximum number of intervals
Number of duration intervals with microbursts: The Detail Chart shows the count of microbursts that occurred in each duration interval. There can only be one microburst per duration interval This number is also used to calculate the percent of duration intervals with microbursts.
Table 38 shows how changing one variable changes the calculations and can affect what you see in your charts.
Table 38. Changing interval, duration, or MB Utilization
Interval 5 ms1 , 2 , 3
Interval 200 ms1,2,3
Interval 1 s1,2,3
Duration 1 ms1,3, 4
Duration 100 µs1,3,4
Duration 10 µs1,3,4
MB Util 10%1,2,4,5
MB Util 50%1,2,4
MB Util 90%1,2,4
Bits/sec in Interval
2,500,000
100,000,000
5,000,000
5,000,000
5,000,000
5,000,000
5,000,000
5,000,000
5,000,000
Bytes/sec in Interval
309,672
12,338,304
61,688,484
617,826
617,826
617,826
617,826
617,826
617,826
Bytes/sec in Interval with IFG
319,500
12,500,000
625,000,000
625,000
625,000
625,000
625,000
625,000
625,000
Megabytes/sec
0.298
11.921
59.605
0.596
0.596
0.596
0.596
0.596
0.596
# of packets/Interval
204
8,128
40,638
407
407
407
407
407
407
Max # of microbursts in Interval
5
200
1,000
10
100
1,000
10
10
10
Max bits of duration from Utilization Threshold
500,000
500,000
500,000
500,000
50,000
5,000
500,000
500,000
500,000
# of bits per Duration for microburst
250,000
250,000
250,000
250,000
25,000
2,500
50,000
250,000
450,000
# of packets in Duration
20.319
20.319
20.319
20.319
2.032
0.203
4.064
20.319
36.573

1 Frame size is 1514, Frame bits are 12,304, Capture adapter speed is 1 Gb, and Network utilization is 50%.

2 Duration is 1 millisecond.

3 Microburst Utilization threshold is 50%.

4 Interval is 10 milliseconds.

5 Microburst Utilization.