Internet telephony gateway location

Abstract

Although the Internet was designed to handle non-real time data traffic, it is being used increasingly to carry voice and video. One important class of contributors to this growth are Internet tele- phones. Critical to more widespread use of Internet telephony is smooth interoperability with the existing telephone network. This interoperability comes through the use of Internet Telephony Gateway's (ITG's) which perform protocol translation between an IP network and the Public Switched Telephone Network (PSTN). In order for an IP host to call a user on the PSTN, the IP host must know the IP address of an appropriate gateway. We con- sider here the problem of finding these gateways. An analysis of a number of protocol architectures is presented, including hierar- chical databases, multicast advertisement, routing protocols, and centralized databases. We propose a new protocol architecture, called Brokered Multicast Advertisements (BMA) which serves as a lightweight, scalable mechanism for locating ITG's. The BMA architecure is general, and can be applied to location of any ser- vice across a wide area network.