Paper review : End-to-End Packet Delay and Loss Behavior in the Internet (Bol93)
Reviewer : Hai Fang (firstname.lastname@example.org)
To understand the packet delay and loss behavior in the Internet.
This paper presents a simple method to measure the round trip delay and
loss behavior in the Internet. Understanding this behavior is important for
the proper design of network algorithms such as routing and flow control
algorithms, for the dimensioning of buffers and link capacity, and for
choosing parameters in simulation and analytic studies.
- Main ideas
- The UDP echo tool can be used for measuring the end-to-end delay and loss
behavior of the Internet.
- The experiment results can be interpreted using a simple single server
queueing model with two input streams, which represent probe traffic and
Internet traffic respectively.
- The observations not only agree with results obtained by others using
simulation and experimental approaches, but also show interesting and less
expected behavior, e.g., the randomness of the probe packets loss.
- Significance rating: 3
Many studies of packet delay and loss in various network environments
have been reported in the literate. (2)
The method proposed in this paper is simple but effective in the scale of
the whole Internet. (+1)
- Convincing rating
First, the author give a review on different approaches, including analytic,
simulation, and experimental ones, for the delay and loss measurement problem.
Then a simple experimental method using UDP echo tool was proposed. The
experimental data was analyzed by a queueing model. The examples, e.g., the
calculation of the bandwidth between France and US, the phenomenon of probe
compression, support the correctness of the model.
This method needs a well-controlled experiment, say, the packets need to be
send at regular intervals. It also need to know more information about the
parameters and testing route than the general experimental methods.
Simple tool and simple model sometimes lead to a concise but useful analysis,
if there is some.
- It seems that there's a typo in the last column of Table 3, the ulp for
delta=500ms should be 0.07 or 0.097 instead of 0.97 from the analysis
followed the table.
- For the bandwidth problem, is it feasible to do a test on each hop of
the route from the source to the destination? For example, we may calculate
the bandwidth between node 1 and i (1 < i <= 10) in Table 1, and get the
bandwidth is b >> 128kb/s between node 1 and j (1 < j <5), whereas
approximately 128kb/s between node 1 and k (5 <= k <= 10); hence we know
that the bottleneck in this route is between node 4 and 5.