An architecture for large-scale IP telephony networks

• Main Author: Terzis, Dimitrios
• Published: University College London (University of London) 2006
• Subjects: 621.38215
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444218

After the explosion of Internet and World Wide Web use in the 1990s, the Internet Protocol has become the de facto standard for networked multimedia communications, sidestepping theoretically superior technologies like Frame Relay and ATM. This fact, combined with the higher efficiency of packet switching over circuit switching, has resulted in Voice over IP (VoIP) networks being increasingly preferred to the General Switched Telephone Network (GSTN), a trend that continues to accelerate in the 21st century. However, inherent technical difficulties related to the predominantly "best-effort" nature of IP, have restricted VoIP to the inside of corporate intranets or to the backbone of carrier networks, and no universal "IP Switched Telephone Network" (ISTN) exists to replace the GSTN. This thesis investigates the applicability of the ISTN concept, on the assumption that the establishment of such an infrastructure will require enhanced scalability and tighter integration of technologies related to all three areas of end-to-end communication: the LAN (end users), for whom appropriate applications and usage models must be proposed, so that IP Telephony can be widely adopted the MAN (access networks), particularly those interfacing with the GSTN, so that interoperability is secured and the WAN (backbone), where call routing is expected to be a crucial factor in the deployment of a unified, worldwide VoIP infrastructure. Examining the proposals currently used in the above three areas, reveals a number of shortcomings, which render the introduction of an alternative solution a necessity for ISTN to be realised in the near future. Therefore, a new architecture for large-scale IP Telephony is introduced and evaluated in this thesis, using improved designs for three core components, one per area addressed: a user agent for the LAN, a gateway for the MAN and a call routing mechanism for the WAN, which is generally more scalable than existing (and under-researched) ones. Finally, potential enhancements to the proposed architecture are suggested and certain directions for further investigation are identified.