En route to Routing

In the move to the new public network, service providers need to integrate their switch-based voice networks with routing-centric data networks. The path is anything but clear

Today's seemingly endless quest for more bandwidth, faster transport and greater reliability has left network engineers searching for the ideal network to service a combination of voice and data traffic. And this search for solutions has produced a seemingly endless line of options, opportunities and off-chances.

The demand for bandwidth has risen in stages. First, users wanted to exchange data. Then, business customers wanted to connect their satellite offices and allow them to share information on a network. Users downloaded Internet pages into their homes.

But they want more.

Now customers want to transmit data, audio and video traffic, play games and control coverage of media events in real time. They want bigger pipes with the ability to transmit multiple media types - often simultaneously.

The telecom industry needs a common infrastructure to address all types of media. Regardless of the efficiency of a converged network, both technically and financially, the service demand for such integration is driving the marketplace to the converged network.

We know that such a network is necessary. The question remains, however, as to how service providers can integrate the best of the voice (switched) and the data (routing) networks to fulfill their customers' multimedia communications needs.

The birth of the switched network occurred more than 100 years ago in 1875 when Alexander Graham Bell invented the telephone. With this depth of history, the technology for the switched network has had plenty of time to develop. The performance, quality and interoperability standards for the switched network have been tested again and again.

Building a switched network today is like opening a cookbook and following a recipe. Even the operations support systems (OSSs) for the switched network have at least a 40-year history in which the industry has perfected the provisioning, monitoring and operations of the network.

But when service providers look to create a network that uses routing and packet technology, there are no directions and little history upon which to build. Whereas the switched network is the patriarch of the communications family, routing technology for multimedia services has not yet reached maturity - it is still in its infancy. All the questions and problems that were solved over the past 100 years with respect to switched networks have no answers when applied to routing networks.

Unresolved issues As the industry moves toward the ideal converged network for data, voice and video, it must address four major unresolved issues: standards, scalability, care of the network and quality of service (QOS).

Standards. As we move beyond the scope of the recipe book for the switched network, the necessity to re-invent the standards on which the routing networks are based becomes clear.

With multiple companies creating the hardware and software for the networks, we find issues of conflicting standards.

Certainly, both the government and the telecom industry have come to realize that competition is a good thing and should be encouraged. However, in the rush for companies to differentiate themselves and gain market share, we run the risk of the networks not being able to communicate with each other.

Already, there is pressure from telecom companies and international organizations to push vendors to work with each other to establish standards. Subsequent cooperative efforts have begun to produce standards.

In support of the interoperability issues, some service providers have insisted that vendors only provide technology based on open standards rather than on proprietary standards, so there are fewer problems connecting traffic to and from other networks. Standards are needed for the various new impairments such as latency that are introduced by a routed network.

Scalability. The architecture of the routing network calls into question its scalability. The service layer architecture currently being examined has not proved that it will scale up to millions of customers and calls.

Certainly, telecom companies are working with their vendors on the scalability question, but the problem is that vendors have different approaches to answering the question. Some vendors distribute more of the call control using proprietary protocols while others are centralizing the call control via standard protocols.

Care of the network. The OSS for the switched networks has a 40-year history. That's 40 years to create, test and improve the billing, provisioning and monitoring of the network. As with the routing network itself, the OSS for routing networks is in its infancy.

The routing network, at first glance, is sometimes thought of as a simpler model than the switched network. The routing network, however, requires more pieces. Each piece has its own software - running into millions of lines of code, and when you change software, you get problems. Thus, even as we look to update billing for routing, changing that software affects other aspects of the network, complicating the process.

QOS. In today's circuit switched network, QOS has been refined over the last 100 years. Reliability of each component, traffic rules and service quality have all been precisely defined and adhered to by the communications community.

Similar efforts are needed for the routing network. Routing networks have not been built with the same level of redundancy and reliability. Router software is still the source of a significant amount of troubles. Software updates affect services. Equipment sites do not have power reliability. Techniques to give the QOS necessary to multimedia services are not yet in place, although techniques and standards are now becoming available.

Why switch to routing? Is the hassle to address these issues worth the effort?

From the service provider's point of view, the ability to have a single infrastructure that can properly accommodate multimedia services offers significant operational and capital savings. From a human resources perspective, using one network means needing only one knowledge base, rather than having two sets of technicians that duplicate efforts for different knowledge bases. It also means only one OSS.

From the customer perspective, the ability to use one network for voice, video, data and other media types means only one pipe going into their premises. The customer can receive enhanced services such as customized incoming call management and unified messaging - services that are only possible with a converged platform.

The future of the communications industry is certainly moving toward the converged network. What remains to be determined, however, is the speed and efficiency at which service providers can move to that converged platform, providing quality services for time-sensitive traffic such as voice, video and data.

Because the routing networks are packet-based, time-sensitive traffic has not reached the quality level that the public has come to expect from switched networks.

When a customer makes a voice call on a switched network, that call has a dedicated channel; the voice traffic is transmitted in real time and is not interrupted.

Voice traffic on a routing network travels the same way as data - in packets. The network breaks down the voice transmission into packets, sending each packet through the network with its own address. When sending packets of data, the packets arrive at the destination end point, not necessarily in the same order as they were sent, and are put back in the correct order to be comprehended by the end user.

With voice transmissions, or other time-sensitive traffic, the packets need to be delivered to the destination end point in the proper time sequence and in the correct order. Otherwise, the transmission will be intelligible.

Another issue when using such a data-oriented system as the routing network is the robust nature of the network. Ask yourself: How often do you get a busy signal dialing up the Internet vs. making a regular phone call? And how often do you have to reboot your computer vs. your phone? The robust nature of the routing network is not yet to the level that customers expect from a switched network.

Packet-based technology is a best-effort system. To address the time-sensitive applications, providers must adopt circuit-switched technology.

A future unforeseen These are the types of issues that have yet to be resolved before providers can move entirely to the converged platform, taking the best of the data and voice networks. Are we there yet? Not quite. But industry leaders are working hard on moving to the standard, open network by opening the doors to an unforeseen future. Standards and technology solutions are emerging that should open the door for broad deployment beginning next year.