VoIP complicates test
With VoIP systems now receiving serious attention, communications test must embrace increasingly complex demands.
Richard A. Quinnell, Contributing Technical Editor -- Test & Measurement World, 11/1/2005 2:00:00 AM
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READ OTHER NOVEMBER ARTICLES:
Table of contents, Nov. 2005 NOVEMBER FEATURES: Bringing home the data Beyond at-speed Protecting the tester VoIP complicates test Sometimes, analog is better |
Recovering from a false start in the mid-'90s, voice over Internet Protocol (VoIP) has re-emerged as a viable contender for telephony applications. Transmitting time-critical voice traffic over the data-centric Internet Protocol has required the development of complex protocols, which in turn has led to dramatic changes in network communications test. One of the changes that VoIP is bringing to communications test is a huge growth in the market for VoIP test equipment, according to analysts Sankara Jambulingam and Olga Yashkova of market research firm Frost & Sullivan. In their report, "World VoIP Test Equipment Markets," the analysts foresee the market blooming from $215.8 million in 2004 to nearly $640 million in 2008, an annual growth rate of more than 30%.
The market expansion includes R&D and manufacturing equipment, but Yashkova said that the biggest growth is in system monitoring and troubleshooting equipment, a market that should expand by more than 50% each year. Jambulingam explained, "As the size of VoIP networks expands, the scalability limitations of open source tools has come to light. Unlike data communications, which can tolerate delay and changing data rates, anything that goes wrong with voice is instantly felt by the user." This sensitivity to timing makes monitoring and troubleshooting large networks critical to providing the quality of service (QoS) that users have come to expect from telephony systems.
Test equipment challenges
Test equipment vendors participating in this growing market face significant challenges, according to the analysts. Because standards for VoIP are still evolving, test equipment must be capable of interpreting a variety of protocols and must also be able to detect interoperability issues arising from differing implementations of protocols. In addition, the analysts noted, the equipment needs to be relatively easy to use. Voice applications are highly complex uses of the network that cannot be treated as simply another application, they said. The more the equipment can simplify delving into that complexity, the better.
Test engineers also face a challenge: blending VoIP systems with traditional time-division multiplexed (TDM) switched-circuit systems telephony. Handling blended systems will require the use of traditional audio telephony and data network test equipment as well as an understanding of both SS7 and Internet Protocol, according to Bahaa Moukadam, VP of IP telephony at Spirent Communications. "One thing we are seeing everywhere, both on the VoIP equipment side and the telephone carrier side," said Moukadam, "is that they [engineers] have in-depth knowledge only of their side. Merging VoIP and switched-circuit telephony needs a deep understanding of both."
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| Full evaluation of VoIP and IPTV designs will require testing in a complete system environment in order to ensure that the customer experience will be as desired. Courtesy of Spirent Communications. |
To meet that need, Moukadam says, VoIP developers are turning to their test equipment suppliers. "More and more customers are saying that they need help with expertise as well as tools," he said. He added that customers are also asking for help in creating test plans and test methodologies.
System test demands scalability
Regarding the needs of VoIP test equipment, Moukadam agreed with the Frost & Sullivan analysts. An ability to handle both protocol variations and scalability is essential, he said, particularly scalability. He noted that testing must be able to simulate an entire network of mixed traditional and VoIP telephony along with data communications, all at varying load levels. This requirement implies that some VoIP test equipment will need high performance if it is going to help evaluate equipment targeting a large enterprise environment. Spirent, for example, offers its Abacus 5000 test system, which handles analog, TDM, and VoIP calls with 50,000 IP phone calls under test.
Moukadam also commented that VoIP test equipment must go beyond simply testing against the protocols and must include evaluation of their voice quality. "To test voice applications by looking only at the IP level is not enough," he said. "QoS tests need to evaluate the subscriber experience."
Blended-nature telephony systems are likely to be in place for a long time as VoIP slowly replaces traditional telephony, first for enterprise customers and then working outward to replace telephone systems for residential customers. In order to provide the kind of user-level-experience testing that Moukadam recommends, test engineers will need a full suite of both VoIP and analog test equipment for conducting end-to-end tests in a blended system.
Many pieces of the puzzle are available, as some manufacturers have begun to offer equipment for voice quality and network testing as well as network analysis in VoIP systems. In addition, you can also find an array of Ethernet analyzers and traditional telephony test equipment products on the market.
More challenges await
Yet, even while test equipment vendors are embracing the need to test blended systems, new applications and challenges are arising. One is the "triple-play" combination of data communications, VoIP telephony, and Internet television (IPTV). As with voice, video signals require sophisticated protocols in order to generate a user experience comparable to that of conventional cable and satellite television. Emergence of the IPTV application will continue and compound the challenges faced by test equipment vendors.
Nor will the challenges stop there. There is also a move within the industry to combine wired and wireless communications systems. This blending of two approaches will affect test equipment in an exact parallel to the effect that blending voice and data has on wired networks. Test engineers will need to develop familiarity with both types of networks, which are substantially different, and test equipment vendors will need to be there to help.
The impact of all these changes will be an expansion of requirements for communications test. Lab equipment, field equipment, and test engineers will need to stretch their capabilities to be able to cover the diversity of equipment and protocols involved in communications. This, in turn, represents a tremendous opportunity for those with enough reach.
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