When the mouse is set to the drags option in the lower-left corner of the window, clicking on a dot brings you to the matching packet in the capture window. As you can see in the following screenshot, a sequence number slightly higher than 872,000 is transmitted in packet 8119, about 15.24 seconds after the start of capture, and then again in packet 8191 at 15.35 seconds after capture start:

In the following screenshot, we can see the result of clicking on these two dots in the time-sequence graph. The first packet, packet 8119, has the sequence number 872674 at 15.248 seconds since capture started:

In the following screenshot, you can see the second packet, with the same sequence number, at 15.25 seconds after the start of capture. When a sequence number repeats itself, this is called TCP retransmission, and will be covered in Chapter 10, Network Layer Protocols and Operations.

When viewing a graph, the important thing is to know what the application is. A graph that indicates a problem in one application can be perfect network behavior for another application.