On Modeling a Bottleneck Link using Dummynet

Developing a communication network of any system must continue to improve capability and scalability. However, development without a plan will cost a lot of energy and costs; this requires a testing system implemented as a network testbed. Testbeds are classified into two, namely physical testbed and virtual testbed, where virtual testbed is superior in terms of cost and scalability. To create network links in a virtual testbed, we propose using Dummynet which can emulate real network conditions. Performance comparisons were made between a particular Mikrotik router (as a physical device representation) and Dummynet using virtual machine (VM). Experiment results show that Dummynet is better in terms of bandwidth-limiting accuracy, with 95.56% to 97.16% accuracy, compared to Mikrotik router, with 91.09% to 95.07% accuracy. On the other hand, Mikrotik router has the advantage of a relatively stable packet delay. In contrast, Dummynet has an additional delay with a maximum value of 6.06 ms at 64 Kbps bottleneck bandwidth. Dummynet is still relevant for implementing network links in a virtual testbed, when physical delays are above that measured additional delay.