While troubleshooting a Wifi performance issue on a large BYOD network, I was explaining to the customer a lot of people on a wireless network sending a lot of small packets can cause a performance issue by robbing precious time from other Wifi clients.
They didn’t quite understand how this could happen since many users’ computers and phones are idle and just simply connected to the WiFi network. I illustrated the impact of having common applications installed on a smartphone/tablet as well as browser extensions or add-ons would have on a network by using Wireshark.
The trickiest part of this exercise is actually capturing the Wireless packets. You can use Riverbed’s Airpcap adapter, or any other vendors WiFi packet capturing product. Just keep in mind that in many cases where you have encryption enabled, its easier if you join that network to see the packets.
To this day I am surprised how many network analysts lack WiFi troubleshooting tools and either rely on their wired lan tools or strictly use the vendors monitoring applications as their sole source of information. I remember a few years ago I did a tools presentation for a vendor and asked the group how much confidence they would have in their auto mechanic if he only had one tool on the bench, or if he lacked specialty tools for your specific car’s make and model.
With Wireshark I was able to give them an ‘under the hood’ view of their network. You don’t need to have an extensive protocol analysis background to quickly realize that this is one busy network. As I have many times in the past, “Packets don’t Lie”.
On a wired network this is less of an issue since a wired network is more bandwidth bound. On a wireless network at home this isn’t an issue either since you aren’t sharing the wireless network with as many people.
In this case, the customer had over 200 people on an access point which cumulatively creates an issue.
In this video I use Wireshark to illustrate the traffic generated by these various applications.