Comparison SIP and IAX to Voice Packet Signaling over VOIP

Abstract

Within the VolP networks environment, there are three protocols that solve the problem of voice packet signaling, known as "highlight protocols": H323, SIP and IAX. Particularly, this document focuses on a specific difference between SIP and IAX: the bandwidth, which is an essential parameter in order to design and optimize a VoIP network for an organization. One of the most important factors to consider when building VoIP networks is the proper capacity planning. About capacity planning, bandwidth calculation is an important factor to consider when designing and troubleshooting packet voice networks for good voice quality. This paper presents important explanations about the bandwidth utilization over VoIP networks, this include o take some theoretical foundations and calculate the bandwidth per media flow for a VoIP trunk, in which different voice codecs is enabled (specifically G. 711 and JSM) and when a VoIP protocol such as SIP and IAX. Voice over IP (VoIP) is used. These calculations will be compared here against the results obtained stats about traffic analysis from some network analyzers over a physical Ethernet trunk between two Asterisk servers into a specific LAN, simulating two different branches for an organization. Both the analysis of the results obtained and the proper conclusions from this work, are useful when calculating the maxim number of simultaneous calls or the minimal capability of a data link, necessary for a single number of voice conversations, taking into account the audio codecs used and signaling and data flow protocols.