In addition to seeing indications of problems within a capture, you can also easily spot issues using the Intelligent Scrollbar, which is on the right-hand side of the packet list panel. In the following screenshot, we see indications of network congestion within the packet list:

The Info column header on the right-hand side lists several indications of trouble that warrants further investigation. These include the following:

• [TCP Out-Of-Order]
• [TCP Retransmission]
• [TCP Dup ACK 587#1]

In addition to the coloring in the packet list, on the right-hand side, there is a distinct coloring pattern based on the coloring rules set in the application, which is the Intelligent Scrollbar. The administrator can click on a color band and go directly to the specified packet in order to zero in on a possible problem. Once you click on a band, Wireshark will adjust the packet list to display the area of concern.

We can see how the coloring rules and the Intelligent Scrollbar identify transmission errors and trouble spots in the capture. In the next section, we will explore common transmission errors that occur on a network.