Case study 2 – Sluggish downloads
In this case study, we will look at a trace file that contains frames from a download occurring at the system of a user who was complaining about sluggish downloads.
Analysis
After simulating the same download that the user performed and capturing traffic at his system, we came up with a huge trace file and hence filtered the traffic (using tshark) on a particular IP from which the download was streamed.
The first thing to note when checking for latencies is the delta time and, more specifically, the TCP delta time when downloading over TCP. Sorting the traffic on TCP delta time, we see a significant delay in time, as highlighted here:
High TCP delta time
A graph can also be created indicating the high TCP delta time, which can be imperative for showing and explaining the problems to others.
This graph can be generated by performing the following steps:
Go to Statistics | IO Graph.
Under the Y Axis section, select Advanced from the Unit drop-down menu.
Select MAX...
