The "new public network" or "next generation network" as it is sometimes called, is the convergence of the PSTN (public switched telephone network) and the Internet (or at least Internet-based technologies) into a new network that is a packet-oriented, multiservice (voice, video, data) network. Its most defining feature is that it should provide the same level of guaranteed service for voice on a packet network that the PSTN provides on a circuit-switched network. The NPN is essentially the Internet with full support for voice and video and backward compatibility with the PSTN.

The development of this new network is being driven by a need to move beyond the centralized control of communication services that the carriers now hold. Deregulation is pushing the telecommunications industry to move to a model that is based on open market competition. In addition, customers are demanding new services, and competitive carriers are supplying them. Packet-switched networks are based on the concept of intelligent end devices that run any application the user chooses. This is counter to the PSTN model, in which the end devices (telephones) are dumb and the network is smart. Packet networks will eventually disrupt the 100-year-old phone system. In the meantime, the old and the new must coexist. One thing the telephone network has going for it is high availability. It is available 99.999 percent of the time, which translates to 5 minutes of downtime per year.

The NPN is a merging of the best features of the PSTN and Internet. It has the following characteristics:

• It is a converged public network made up of many providers using the distributed model of the Internet, but many of its features come from both the Internet and PSTN.


• The network is built on open standards and nonproprietary equipment that easily interconnects.


• The new network is distributed, meaning that intelligence is not centralized in the network but moves out to smart edge devices (PCs, smart phones, PDAs, and so forth). New services are easy to create in the NPN because they are created at the edge (by simply installing an application) rather than in the network.


• All forms of communication, including voice, video, data, and telecommunications are supported.


• The circuit-oriented, TDM-based hierarchy built on the 64-Kbit/sec digitized voice call will eventually be replaced.


• While the PSTN was optimized for constant bit rate, narrowband, connection-oriented traffic, the new network is built for variable bit rate, connectionless traffic.


• Bandwidth is abundant, but the network contains enough intelligence to allocate bandwidth and provide guaranteed service. While the traditional Internet is a best-effort delivery service, the new network will provide guaranteed QoS via virtual circuits and traffic engineering. This is made possible by implementing MPLS and improving the core with optical networking technologies.


• The NPN provides fault tolerance and high-availability features of the circuit-oriented PSTN, features that are sorely lacking in the Internet. When was the last time your phone didn't work or your 911 call didn't go through?


• The NPN will require intelligence that supports customer service demands, such as bandwidth on demand. This calls for network services such as policy management (to determine who can get the services), accounting, billing, and security.

The ability to create new services at end devices is perhaps the most important feature of the NPN. The telephone companies offer a relatively limited set of services, such as caller ID and call waiting. These services are configured within the carrier network itself. If you want a service, you request it from the network by pressing buttons on the keypad. For example, you press *69 to have the carrier redial the last person that called you. Think about it. With the PSTN, the 12-digit keypad is your user interface. On the Internet, a Web browser is your interface. Which would you rather have?

Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.
All rights reserved under Pan American and International copyright conventions.