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Assuring VoIP Quality for Triple Play: It's a Whole New Ballgame
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Testing a network before service turn-up is also crucial to uncovering configuration mistakes that could lead to quality problems. For instance, if gateways are not configured for proper IP address to phone number translations, calls cannot be set up. Router configurations must be accurate to enable optimal forwarding and QoS for voice traffic, which can be accomplished by implementing DiffServ prioritization and queuing, and MPLS traffic engineering. In addition, queuing choice and configuration are also critical because incorrect queuing can cause inappropriate packet delays.
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Post-Deployment: A Look at Services
The services side mainly involves assuring quality after the service is in the production phase.
There are three aspects of a good VoIP service assurance solution:
* Fault management, or the identification of fault events (via alarms) in the network and the correlation of these events
* Performance management, or the collection and trending of performance-related data over time for customer reporting and proactive monitoring purposes
* Diagnostics, or the ability to identify the exact cause and required repair for a known performance or fault event
By far the most important aspect of the three listed above is diagnostics. Good diagnostic solutions can decrease a service provider’s mean time to repair by 50 percent – while also allowing less skilled technicians to easily diagnose network problems.
Uncovering the Various Layers
Having a good diagnostic solution is particularly critical when supporting triple play services, where the same transmission equipment is often used to support a variety of different applications. This makes it very difficult to uncover what equipment is causing a particular problem. That is why one of the most critical features of a good diagnostic system is the ability to diagnose problems across the various layers of the network using one integrated tool.
For instance, a quality issue in Layer 7 – the application layer – may not be caused by a problem in that layer. It could be caused by a Layer 1 problem – that is, a physical layer problem – that was created by a backhoe that brought down the connection to a DSLAM. Or it could have been caused by a Layer 2 problem – for instance, by a glitch in the Ethernet switch that was causing traffic to be sent to the wrong location. With the ability to run tests at different layers – as well as within layers – technicians can quickly isolate the problem to a specific protocol or equipment without having to be IP experts themselves. Even further diagnostics can also be conducted to isolate problems to a specific network segment.
Without the ability to diagnose services issues across layers, resolving them becomes much more complex. The inability to correctly diagnose network problems can actually cost service providers money. For instance, one Ethernet service provider was paying a customer rebates every month because the customer claimed that the service provider was not meeting the quality standards outlined in its SLA. Using diagnostic tools, the service provider monitored the customer’s traffic and discovered that the customer was exceeding the agreed upon bandwidth, which was in turn causing dropped packets. The service provider no longer had to pay rebates, the customer was able to reconfigure their equipment, and the problem was easily fixed
The bottom line is that offering triple play services – whether they are delivered to enterprises or residential customers – introduces complexity into a network, which in turn makes the need for network testing critical. As more and more VoIP providers enter the marketplace, ensuring high quality VoIP services from day one of deployment will be imperative to retaining customers. After all, isn’t creating sticky customers the goal of offering triple play services to begin with?
About
the Authors
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Beth Wingerd is the Senior Director, Product Line Management for Spirent's IP Services products. She has almost 20 years of experience in the telecommunications industry with particular emphasis on data services such as IP, ATM, Frame Relay and Ethernet. Prior to joining Spirent, Beth held executive positions in product management and engineering at TTC, Acterna and Seneca Networks working on products for domestic and European markets. Beth holds an MBA from the University of Maryland and a Masters in Computer Science from West Virginia University. She is the author of an article "Distributed Monitoring and Analysis", Handbook of Local Area Networks, Auerbach Publications.
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Andy Huckridge leads Spirent's go-to-market strategy for the IP Telephony market. His responsibilities include business planning, market development, and product management. Andy has worked in the communications industry for 10 years, including roles at Centilo, Inc, and 8x8, Inc., where he was director of Product Marketing. Andy has a broad background in defining and marketing products in the semiconductor and IP Telephony space. He earned his Bachelors and Masters Degrees in telecommunications engineering from the University of Surry in England. Andy is active in the SIP Forum and Multi-Switching Forum where he is Vice Chairman of the Interoperability Working Group.
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About
Spirent Communications
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Spirent
Communications is a global provider of integrated
performance analysis and service assurance systems that enable the
development and deployment of next-generation networking
technology such as Internet Telephony, broadband services, 3G
wireless, global navigation satellite systems, and network
security equipment. Spirent’s solutions are used by more than
1,500 customers in 30 countries, including the world’s largest
equipment manufacturers, service providers, enterprises and
governments.
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