Optimum VoIP packet routing using a communications processor

Abstract

This article presents a new architecture for the VoIP media gateway using only a communications processor and digital signal processors. The new architecture can be used by telecommunications equipment manufactures to replace a network processor and a general-purpose processor with a single communications processor, thereby can reduce the system cost, power consumption, printed circuit board (PCB) area, software complexity and time to market. In the new architecture the modules are interconnected via Ethernet interfaces, which make voice packet encapsulation possible in digital signal processors. This relieves the network processor, which in voice over IP (VoIP) media gateways is most commonly used for the routing of VoIP packets and voice-packet encapsulation, and means it can be replaced by a communications processor. The presented media gateway architecture makes it possible to combine the data- and control-plane application on a single-communications processor, but only in the case of a properly optimized program code and an optimized Ethernet driver. Therefore, the main part of the article is dedicated to a presentation of the methodology for the analysis and optimization of the presented systems. In order to support this methodology, a new tool named performance monitor (PM) was developed. The PM tool is presented here, and was used for optimizing the Ethernet driver. The Ethernet driver was optimized and modified in such a way as to put a minimal load on the microprocessor core of the communications processor when routing the VoIP packets to digital signal processors and back. The article ends with a presentation of the experimental optimization results, which were acquired from a real telecommunications system.