LARTC: trace control for netem

Hi,

We developed an extension to the network emulator netem, that provides emulation of long term network properties such as long-range dependence and self-similarity of cross-traffic. It is not possible to emulate these properties with the statistical tables for the packet delay values used by the original netem.

We read the values for the packet delay, drop, loss and corruption from a pre-generated trace file. This trace file is obtained by monitoring network traffic and writing all actions to a trace file. During the emulation the packets get processed according the values in such a trace file. Detailed information are available on our Webseitehttp://tcn.hypert.net

A new option (trace) has been added to the netem command. If the trace option is used, the values for packet delay etc. are read from a trace file, afterwards the packets are processed by the normal netem functions. The packet action values are readout from the trace file in user space and sent to kernel space via procfs.

The evaluation results show similar behavior for our enhancement and the original netem with respect to packet delay precision and packet loss at high load (e.g. 80'000 packets per second).
It is possible to add, change or delete multiple netem qdiscs on-the-fly (original netem qdiscs and trace qdiscs mixed).

We are looking forward for any comments, feedback and suggestions!

Thanks,
Rainer