Improvements in OMNeT++/INET Real-Time Scheduler for Emulation Mode

TL;DR

This paper evaluates and improves the real-time scheduler in INET's emulation mode, significantly enhancing delay precision and responsiveness, while discussing trade-offs in packet capturing methods.

Contribution

It identifies implementation errors in INET 2.6, proposes a modified configuration, and demonstrates improved performance in INET 3.0 for emulation delay accuracy.

Findings

Delay emulation precision improved significantly in INET 3.0

Responsiveness of emulation mode increased with modifications

Packet loss in capturing increased but is a known issue

Abstract

In this paper the performance of INET's emulation mode is evaluated. In particular, the focus of the study is on the precision of the delay emulation. It is shown, that this precision is low in INET 2.6 (respectively a later version provided in the integration branch that fixed the crashes of 2.6 in emulation mode). Two errors in the implementation are identified and an alternative configuration for packet capturing is proposed. The performance tests are re-run with such a modified version of the real-time scheduler (which is now included in the recent INET 3.0 release) and it is shown that the responsiveness of the emulation mode and the precision of delay emulation are improved significantly. Finally, the negative impact of the modified capturing configuration is briefly analyzed. Packet loss in the capturing process has deteriorated but in fact is has already plagued the emulation mode of previous implementations and this topic clearly demands for further studies.