Scroll through the graph in order to identify bursts. Change the tick interval to X Axis=0.001 sec and the scale to Y-axis= (bits/tick). Recalculate the scales on the X and Y-axes. Change the Y-axis to bits/tick because interfaces show output rates in bits/sec. If you make the scales more granular, you see a more accurate picture of the actual traffic profile.

However, if a major portion of this traffic attempts to leave the interface in a fraction of a second, the switch needs to extensively buffer packets and drop them when the buffers are full. In a period of one second, a 1 Gb/s link can accommodate 1000 Mb of traffic across the interface in a neatly-shaped profile with a minimum need to buffer any packet. However, one second is a very large interval when you consider the rate at which buffering and packet switching happens. Open the captured file in Wireshark and plot an IO graph like this one.Īt the default scale, it appears that there is no bursty traffic.

In order to capture this traffic, connect a PC that runs Wireshark and capture packets at the mirror destination port.

For example, you notice output drops on a 1G link while the average utilization of the link is only 150Mb.Ĭonfigure an egress mirror on the switch in order to capture transmitted (TX) traffic. Identify an interface that has incremental output drops.

What is wireshark io graph