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Doing the Math: Bell Labs'
Analysis Tools Optimize VoIP Networks
May 18, 2004
Iraj Saniee, Anwar Walid and Indra Widjaja (left to right) in the Bell Labs Mathematical Sciences Research Center are designing analytical tools that help Lucent master some of the difficult issues behind VoIP networks.

Service providers are eyeing Voice over Internet Protocol (VoIP) technology with more than just a casual interest. The question today isn't will they deploy it -- it's how, when and where they will deploy it -- and how much will they save? A small team in Bell Labs Mathematical Sciences Research Center (MSR) in Murray Hill, N.J., is literally crunching the numbers to provide answers that will help optimize network migration for customers.

Iraj Saniee, Bell Labs director in the MSR, Murray Hill, and his team are keenly focused on the mathematics of networks and systems, and are "doing the math" and designing the analytical tools and mathematical models that are taking the guesswork out of deploying new VoIP networks that are based on Lucent's Accelerate™ VoIP Solutions.

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* The technology behind VoIP networks is like a river being fed by many tributaries -- the technology has been growing for years and is starting to crest now with actual deployments to meet customer demand.

Debasis Mitra
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That keen focus is nothing new in the MSR center. "Some of our models and tools date back 25 years; others to the early 90s; some are brand new," said Debasis Mitra, Bell Labs vice president, Murray Hill, who leads the MSR. "The technology behind VoIP networks is like a river being fed by many tributaries -- the technology has been growing for years and is starting to crest now with actual deployments to meet customer demand."

Saniee's team is working with the Convergence Solutions architecture team in Integrated Network Solutions (INS) to study the migration of service provider networks to VoIP. This work is applicable to all of the products in Lucent's Accelerate™ portfolio, including the Lucent Softswitch and the 5E-XC™ switch solutions. The collaboration between the two teams covers four areas: the trunk capacity benefits of IP networks; VoIP call admission control; optimization of migration plans with capital and operating expense quantification; and efficient support of new VoIP services.

"These are very difficult problems and it would be nearly impossible to solve them without the knowledge and experience that the math research team brings to the table," said Mike Morris, director, Convergence Solutions Architecture, who leads the architecture team in Naperville, Ill. "I've worked with the math center's teams before and have grown to respect their abilities even more. This collaboration will help differentiate our products from our competitors."

Real World Solutions
For example, Saniee's team already is working with Convergence Solutions and large service providers to model various migration scenarios using its new Circuit-to-Packet Migration Optimization Tool, developed jointly with Qiong Wang, member of technical staff, MSR, Murray Hill. The tool can help service providers develop realistic plans for how much circuit-based voice traffic to migrate each year to IP networks based on their specific needs.

"One service provider might want to migrate to a converged network gradually over the next five years to gain confidence with the technology, to consolidate building space or for any number of other reasons, including budget constraints," said Anwar Walid, distinguished member of technical staff, MSR, Murray Hill.

According to Walid, the service provider has to juggle numerous variables, including the cost of circuits today, next year and the years after; the operating and capital costs of running an IP network or a converged network; projected traffic, whether it's voice or data; budget constraints; and even inflation.

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* The value of our circuit-to-packet migration tool is that once all the necessary data is collected and populated into the model, we can perform an optimization indicating how much traffic to migrate each year to optimize the network within the constraints identified by the customer.

Anwar Walid
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Risk also is a factor. For example, as a service provider migrates to an IP network, it must add capacity. "Capacity comes in different costs and granularities, and the costs typically drop every year," said Walid. "If a service provider deploys all the new circuits in a single year, it loses the advantage of lower circuit costs in future years."

Traffic projection for existing or new services is another area where costs have to be considered, added Walid. If too much capacity is migrated or deployed initially and it's not used, the service provider isn't getting the best return on that investment. "The network isn't optimized, and the customer isn't happy," said Walid.

"The value of our circuit-to-packet migration tool is that once all the necessary data is collected and populated into the model, we can perform an optimization indicating how much traffic to migrate each year to optimize the network within the constraints identified by the customer," added Walid.

It Gets Complicated
As service providers continue to migrate to IP and converged networks, "understanding the behavior of the load -- the traffic -- is the key to efficient networking," said Saniee. "One of the major achievements in circuit-based networking was dynamic routing, which came out of understanding the load characteristics during peak traffic periods in the network. By understanding how the load behaves, we can create the mechanisms to control and manage congestion. That's a big part of what we are doing today with Voice over IP networks, as part of our fundamental research."

According to Saniee, convergence is broader than just VoIP, and certainly more complex and nuanced than just saying, "Convergence is one network that does everything." "Ultimately, it can be one network. But today, service providers have a voice network, an ATM network, a frame relay network -- all different, with different protocols to manage them. Eventually, service providers want to migrate to one protocol."

The migration to one network requires in-depth understanding of service provider networks. "That's why our collaboration with Convergence Solutions and their customers is so important," said Indra Widjaja, member of technical staff, MSR, Murray Hill. "Convergence Solutions and our customers benefit from our mathematical tools and analytical skills. We, in turn, benefit because we are exposed to real-world problems and the raw data that helps us understand real-world networks."

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* Convergence Solutions and our customers benefit from our mathematical tools and analytical skills. We, in turn, benefit because we are exposed to real-world problems and the raw data that helps us understand real-world networks.

Indra Widjaja
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Another project the team is working on involves trunk capacity optimization. It's an area that service providers are very interested in because of potential savings. "We have been collaborating with the switching architecture team in Convergence Solutions to develop the Tool for Analysis of TDM and Voice-over-IP Networks with Large Trunk Groups," said Widjaja.

By applying mathematical methodologies, the tool can confirm the capacity benefits and resulting savings of employing packet trunking over TDM trunking. The tool also evaluates other issues, including the implications of various IP network designs. For example, switches in a traditional circuit-based network are interconnected in a mesh design with dedicated trunks and capacities among switches. In most IP networks, capacity is shared among the switches. The new tool, once populated with the appropriate data, can evaluate the impact of a sudden burst of traffic to a specific switch in the network and the impact it might have on the other switches in terms of monopolizing capacity and increasing blocked calls that could negatively affect the quality of service of the entire network.

By essentially optimizing capacity, the service provider not only saves capital expense dollars, but can also realize savings in operational expense, said Saniee.

'We've Done it Before'
In another situation, a service provider has provided the team with the network topology and traffic loads for a very large and sophisticated segment of its network. "We're working with Convergence Solutions on how to analyze the data to understand the network implications of selectively removing and consolidating switches," said Walid.

This team also is involved in analyzing efficient support of new VoIP services such as privacy management, and call admission control that can tell a service provider how many circuits are busy or available in VoIP networks to ensure quality of service.

According to Mitra, the problems and challenges that surface in the field in real networks with real customers "are jewels -- each and every one of them. They are never identical to past problems. They have something typically distinct about them that require us to rethink that problem from a fundamental perspective.

"That is what makes our work here in Bell Labs special," said Mitra. "But without a clear characterization of the problem -- which originates with a customer -- we would not be effective. Out of our combined efforts with the market segments comes better, cheaper, more resilient architectures; better tools and models; and better products, and the services those products will provide."

Lucent is counting on it.

— by John Brooks


Click here to read about the MSR's collaboration with Supply Chain Networks on issues of supply and demand.



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