Dummynet is a popular tool for traffic shaping, and it can
also simulate a link with packet loss, propagation delay, bandwidth and queuing
management. Therefore, it is often used to research and test networking
protocols by simulating the end-to-end Internet dynamics.
Current version of Dummynet only provides packet random loss. That is, every two packet losses are independent. However, according to a lot of existing studies, packet loss in the Internet occurs in a bursty manner, or some packet losses in a row are correlated. In order to introduce an enhanced Dummynet able to emulate end-to-end packet loss in the Internet, we intend to implement some common theoretical loss models into Dummynet.
Three types of loss models will be implemented: 1) Gilbert related models, including Gilbert-Elliott (GE) model and Extended GE model with Multiple States; 2) Kth-order Markov Chain model; and 3) Loss run-length based model, including its generic form and special ones with run-length governed by particular distributions (such as Geometric distribution or Pareto distribution). The project will be carried on under FreeBSD. Since IPFW provides user interfaces for Dummynet, necessary controls will also be added to ipfw2.
Dummynet has already been used widely in the research community, and we believe that adding a few more loss models will be a good contribution to the research and FreeBSD communities.
Homepage of Dummynet's author, Luigi Rizzo