Here’s a fun case study on troubleshooting a one-way performance issue. Of course, the root cause for every one-way performance issue won’t be the same as this one, but it’s a bit of experience to add to your bag.
It’s very important when analyzing packets to take on the perspective of the host from which you captured the data. If it’s the receiving side, then think like the receiver. If it’s the sender side, then think like the sender. To do that and have it lead you to a root cause requires knowledge of what you should expect to see and just plain ol’ experience. So keep at it.
Let me tell you, there was over an hour’s worth of TCP goodness to talk about in this case study so I tried to focus only on the issue at hand to keep it to a reasonable time. I will be coming back to this case study to talk about TCP behavior in-depth in the future.