33001 is the source UDP port of server and 42132 is the source UDP port of the client

Because we know that 33001 is the source UDP port of the server and 42132 is the source UDP port of the client, we can ask Wireshark to plot the number of packets sent per second. As the file is being transferred from the server to my local machine we are not surprised to see that a large number of packets per second are being sent by the server (~8,000 packets per second). While the number of packets being sent to the server is a very small number of packets per second. At the beginning of the file transfer the number of packets being sent per second is small and rapidly increases. However, we notices that there are a number of points that fall below the line indicating that the packet rate was lower for these samples.

Wireshark output for the source and destination ports during the FASP transfer — Wireshark plot of traffic in both directions for the whole FASP transfer. The red dots show the number of packets per second that were sent by the server and received at my local computer, while the black dots indicate the number of packets sent by my local client to the remote server.

Note the packet rate unit is in Packets/tick

Transcript

Now, if we do a plot looking at packet rates. You can see that the 33001, which is the source port of the server, here's the rate at which it is sending packets. So sometimes it decreases but mostly it stays along at about that rate. And in comparison, we can see down here the UDP traffic sent by the client at a very very low rate.