Voice and data convergence in the LAN is about to become a hot topic in the industry, thanks to advances in switching and processors, as well as the H.323 standard. This chapter first looks at the business reasons for considering the deployment of voice and video over the LAN and then discusses the technical issues and requirements. Topics include the value of voice and video on the LAN, infrastructure efficiencies, LAN technologies for integrated voice and video, and standards for LAN-based voice and video applications

Most desktops in enterprises today are equipped with two network connections: a LAN connection to the PC or work station for data communications and a phone connection to the PBX for voice communications. The LAN and the PBX exist as two separate networks with little or no connectivity between them. Each has evolved to meet the very specific and differing needs of data and voice communications, respectively.

Despite much talk in the industry about the convergence of computers and communications, LANs and PBXs have not really moved any closer together during the last decade. In the mid-1980s, some PBX vendors sought to bring data services to the desktop via ISDN technology, but the advent of PCs requiring far more than 64K-bps communications bandwidth favored the emerging LAN standards of Ethernet and Token Ring. So far, most LAN vendors have not attempted to support voice communications on the LAN. But all this is about to change.

There are three key factors at work today that suggest that voice and data convergence in the LAN is about to become a hot topic in the industry:

•  The widespread acceptance of advanced LAN switching technologies, including ATM, which makes it possible for the first time to deliver reliable, high-quality, low-delay voice transmissions over the LAN.

•  The emergence of the first standard for LAN-based videoconferencing and voice telephony, H.323, which removes objections about the use of proprietary protocols for voice and video over the LAN.

•  The deployment of the latest generation of Intel processors, featuring MMX technology, which makes high-quality software-based real-time voice and video processing feasible for the first time, and the new PC hardware architectures with Universal Serial Bus that permit voice and video peripherals to be attached without additional hardware inside the PC.

This chapter first looks at the business reasons for considering the deployment of voice and video over the LAN and then discusses the technical issues and requirements.

THE VALUE OF VOICE AND VIDEO ON THE LAN

There are essentially two main kinds of motivation for considering voice and/or video on the LAN: the need to support new types of applications that involve real-time communications and the desire to improve the overall cost effectiveness of the local communications infrastructure.