ns, the concept behind conver- gence varies a bit depending on whether you're a service provider, an equipment manufacturer, or an applications developer. In the end, though, they all focus on one thing: bringing together voice, data, and video to be happily married at the network level, at the systems level, at the applications level, and at the device level. Convergence in Transport Convergence in transport refers to voice, data, and video traffic all sharing a com- mon packet-based network, generally based on IP at present. This can apply to LANs, MANs, WANs, and wireless alternatives to each of those domains. From the standpoint of a service provider, convergence has to do with the idea of bringing together all the different technologies we've known in the past to come up with one common infrastructure, rather than working in today's world that consists of a sepa- rate voice network, the PSTN, separate data solutions, the Internet, IP backbones, Frame Relay, and ATM-a variety of different packet-switched alternatives-and then generally also separate networks engineered specifically for video and broad- cast. The problem is that each of these represents a separate control plane, which means separate network management systems and procedures. It means technicians who are trained and knowledgeable in those specific systems, services, and prod- ucts; and, of course, it means greater cost because there's duplication among plat- forms, and you have to make redundant components available and power backups to a large number of what, in essence, are overlays. So, to the service provider com- munity, convergence means the convergence of the transport network. Convergence in Systems There has to be some convergence from the standpoint of the systems. To equipment manufacturers, this means creating systems that allow voice, data, and video traffic to all be commonly served through one device. In the context of next-generation net- work infrastructures, this most commonly refers to the use of softswitches, also known as c