End-to-end internet packet dynamics

This is an interesting (but long) paper on determining end-to-end performance in the Internet. Analysis is done on packet traces of TCP transfers between pairs of end-nodes, where both sender and receiver are under the control of the author. Knowledge of the TCP protocol is also used to undo its effects in order for analysis of the underlying network to be performed.

If there is one key lesson from this paper, it is there there is no single number that describes characteristics such as percentage of out-of-order packets, bottleneck bandwidth, packet loss rates and jitter. These change over time, and depend on sites, network elements, TCP implementation, among others. For an internet application, this probably means constant probing and monitoring of such metircs.

The paper is generally full of interesting tidbits, although I cannot say that there is a consistent theme throughout. Among the many things I learnt was how to robustly measure bottleneck bandwidth.

I wonder if someone has did a similar thing for UDP packets, which might be interesting for streaming applications. While the author points out that TCP has this "harm-no-others" property, is that really a good reason for not looking at UDP? I think a practical reality is what rate to choose to send UDP packets at, since obviously the characteristics would be very different at different transmission rates.