Paper Review: End-to-End Packet Delay and Loss Behavior in the Internet

Reviewer: Mark Meras (mm446)

Main Contribution

This paper by J. Bolot presents a new analysis of end-to-end packet delay and loss behavior by using a "ping"-like mechanism. Bolot confirms previous work on mixing high-bandwidth, large packets with small, interactivity-intended packets. He also claims that the loss of these "ping" packets (called probes) is random in most situations.

Key Ideas

We need to analyze packet delay and loss behavior (i.e. how and when packets are dropped). Packet delay includes both fixed delay (e.g. propagation delay) and variable delay due to routing and queuing delay. Loss behavior needs to be measured as to its frequency and clustering
Analysis was performed using small "probe" UDP packets. The two streams of probe packets and regular Internet packets were mixed together. Analysis revealed that probe packet loss tended to be in bursts.
Other, not so expected, results also occured. Probe packet loss was random unless traffic intensity was very high. Rapid fluctuations of queuing delays over small periods were also common.

Critique of Contribution

Most of the paper does not seem suprising. Clustering of packets during loss has been studied previously. However, the randomness of packet loss in low-intensity situation is an interesting update to the solution. More importantly, it was shown that probe tools can be used to study end-to-end network characteristics.

Open Question

The question remaining is how will multimedia transmissions (such as real-time video) affect the nature of packet loss and delay on the Internet? This is yet to be studied at the time of publication.