Operation: VoIP

Sun, 07/31/2005 - 8:00pm
Craig Kuhl, Contributing Editor

The litmus test for ensuring the peak Quality of Service (QoS),
reliability and performance expected from Voice-over-Internet Protocol
(VoIP) networks is proving to be a tough exam.

The litmus test for ensuring the peak Quality of Service (QoS), reliability and performance expected from Voice-over-Internet Protocol (VoIP) networks is proving to be a tough exam.

As an entirely new exercise for the cable industry, VoIP is mandating new skill sets, tools, equipment and even a fresh corporate engineering culture and mindset for the burgeoning VoIP business, predicted to reach 18 million subscribers by 2009, according to a recent forecast from the Yankee Group.

In turn, the vendor community, which is being asked to design and administer the crucial tests that will pass or fail an IP- enabled voice network, is penetrating deeper into the VoIP testing and monitoring space, a market expected to top $638 million in 2008, reports a Frost & Sullivan survey.

No longer in its trial stages, cable VoIP is now a legitimate money-maker and competitive service which is expected to grow significantly in the next 10 years. Getting to those lofty VoIP numbers will require passing some critical tests, however.

"Cable is the major driver of VoIP deployment and is implementing more test and monitoring equipment into [its] networks for areas such as troubleshooting. But VoIP customers are very sensitive, and cable operators aren't used to that, so they must be more pro-active in their testing and monitoring," says Jessy Cavazos, program manager, Frost & Sullivan.

VoIP networks have their sensitive side, too. Therein lies the test and monitoring challenge. "This is not classic network management," says Randal Burke, senior director for national communications engineering and operations for Comcast Corp. "We need a more dynamic view of nodes before they impact customers, so we have to maintain a quality test and monitoring system to address multiple gateways and track performance issues such as jitter and latency. As we grow, we need to understand how we're pushing the demand of those elements and where the trunk points will be as the scale is pushed higher. These are now very dynamic networks."

Virtually all of the top MSOs, and to some extent, small- to mid-sized cable operators, are growing their VoIP networks and pushing the service hard into their business plans. Consequently, their attitude toward testing and monitoring the ongoing complexities of nascent VoIP networks is getting very serious.

Figure 1
Figure 1: Four stages/segments of VoIP
testing and the equipment needed for each.

"We have to understand where the problem is and get it resolved, fast," explains Charlotte Field, Comcast's senior vice president for national communications engineering and operations. "We're working with vendors to push that strategy. For example, [the use of] equipment to do loop back testing and to get down to a more granular level. We're looking for vendors to work more closely together in the VoIP test equipment segment than in the past. We all have to play nice together."

Playing in the VoIP test and monitoring space can be tricky, however. With PacketCable and security issues key factors in a VoIP network, the predictive aspects of a traditional, hardened circuit-switched network are long gone.

"There are some unique characteristics to testing VoIP, like handling packets and security, and protocol switching, which take longer to process and can create delays. The tough part is trying to place a call on an actual PacketCable level and going live. We're developing gear to place live calls for core IP analyzers and working with MSOs on how to put all this together," explains Kevin Oliver, vice president of marketing for the cable network division of Acterna Inc., a testing and monitoring firm that, at press time, was in the process of being acquired by JDS Uniphase.

"Together" is the operative word in the new world of VoIP testing, admits Stefan Pracht, product marketing manager for Agilent, a VoIP test and monitoring provider. "Piecing together calls from a loosely defined set of protocols and assembling signal messages is challenging. Highly de-centralized architectures require monitoring several different locations, and the role of VoIP signaling will increase with real-time video, streaming and gaming. So, we have to understand the intricate details of the architecture."

Prepping for the peak

With VoIP expected to reach its peak deployment period in 2010, an In-Stat report predicts the cable community is bracing for a steady migration to VoIP service in the next five years, during which time VoIP testing strategies are expected to solidify.

"It's an on-going process to identify weaknesses and stand them up versus baseline elements of packet configurations and root causes, then resolve them. We're beginning to deploy tool sets in PacketCable to build up pro-active data, and our most powerful tool is reactive testing that allows us to extract actual call-in data, dump it into our database and trace the root cause. We see every call and a clear picture of the network's health," says Bruce McLeod, manager of VoIP development engineering for Cox Communications.

Despite the progress in VoIP testing and monitoring, McLeod readily admits much more needs to be done before a faultless testing system and its support equipment is in place. "HFC leakage 101 doesn't change, and we must look at that first. If an eMTA (embedded multimedia terminal adapter) is added, you double the tests, so testing is growing exponentially. That's where it gets complex."

Finding the skilled technicians to multi-task between the telecom, cable and IP worlds and who can speak data, HFC and telecom languages is proving to be a puzzling exercise, as well. Adds McLeod: "Techs with those three skills are hard to find. It's difficult to teach a carrier-class mentality to a cable network person."

Gearing up

Nevertheless, the effort among the cable community and the growing number of VoIP equipment manufacturers to design and integrate a world-class VoIP test and monitoring system is intensifying.

Trilithic, which recently partnered with VoIP test system provider Minacom, is one of several test and monitoring companies that have jumped into the VoIP test market, and is currently bulking up its VoIP segment.

"We've added VoIP tests to our field analyzer for techs—a real time transfer protocol for packet loss, jitter and latency which gets the MOS score (Mean Opinion Score) even before VoIP is implemented," says Steve Windle, product manager for Trilithic, a maker of VoIP field test products. "Now, we're being asked to develop better methods of analyzing return path spectrum data based on new VoIP standards. They (cable operators) want to see what's happening to a node in a 24-hour period in the entire range of spectrum. We need to understand all the service quality measurements, and that is a challenge."

A gaggle of VoIP test product players, including Agilent, Brix Networks, Empirix, NetTest, Spirent, Sunrise Telecom, Tektronix and others are migrating deeper into VoIP testing territory, knowing full well the cable industry's growing VoIP testing requirements.

"We have manufacturing customers who are turning whole divisions into cable related businesses, like VoIP, and designing products specifically for that market. But they still have to handle media gateways and a packetized environment. There are some very dynamic QoS issues specific to cable," notes Jason Steele, product marketing manager for network diagnostics at Tektronix Inc.

One of those issues certainly is customer retention, a primary goal of every cable system contemplating a VoIP rollout. "Marketing will get the sign-ups, but QoS gets the return customers. That's where VoIP testing and QoS are so crucial. Determining if it's an RF or IP problem is something they haven't dealt with before. So, we must make our equipment easier to use for the technicians who have to understand both sides," says Jean-Luc Gelines, vice president of product development and marketing for Montreal-based Sunrise Telecom.

Good idea. Especially for VoIP newcomers such as Adelphia Communications, which is rolling out VoIP this year after taking copious notes on how other MSOs were testing and integrating VoIP equipment into their existing networks. Admittedly, Adelphia is late to the VoIP dance, but there's no shortage of partners, or potential customers.

"VoIP is potentially a greater business than high-speed data and it can lift video and data reliability and quality. It really helps everything. The upfront cost of testing, monitoring and deploying VoIP can be expensive, but if you look at the price points and margins of the product, it's a small price to pay," insists Tom Buttermore, vice president of data engineering and operations for Adelphia.

There are hurdles to overcome, Buttermore admits. For instance, the expectation level of voice service is far greater than video, he says. So the company is adding backup power supplies at its headends and redundancy and powering in the plant.

Pro-actively monitoring the network is another key piece to Adelphia's VoIP testing strategy. Explains Buttermore: "VoIP is very new, so surveillance capabilities become very important. Areas such as back office surveillance, ticketing and network operations become crucial. We're looking at advanced troubleshooting tools and more network probes to isolate the problems, while deploying advanced diagnostic tools with our CSRs. VoIP is prompting very significant changes on how we maintain our plant."

Network probes, he continues, allow you to stair-step down various test points in a network to isolate problems. "How do we look at the dynamics of QoS and where the errors are being generated? All are protocol-specific, so that service level view is critical, before the customers see it. That methodology is key for us, right down to the dispatcher. We're really raising the bar."

And the bar, at least the testing aspect, is far higher for VoIP than for traditional circuit switched telephony, maintains Jeff Walker, senior director of marketing for connected home solutions at Motorola Inc.

"Testing PacketCable is very different than circuit-switched. All signaling must work appropriately, traffic hand-offs are different, media gateways must be addressed and QoS testing is unique. And they require whole new skill sets," he says.

Tests for PacketCable features such as call forwarding and waiting, and voice quality such as jitter, QoS and D-QoS (dynamic QoS), stress, stability and performance testing, along with capacity testing, are key test areas for VoIP, Walker adds.

"When doing voice implementation, we'll replicate their environments in our lab, run all the tests and provide the results. But there is no silver bullet technology or solution to test VoIP. You have to test all the pieces, interpret standards and handling capacity, installs, provisioning, order-taking. That's why companies like Comcast have a calculated strategy. They just want to do it right," concludes Walker.

Doing VoIP testing right, at least the first time, is not exactly a slam-dunk proposition. And with a significant number of VoIP customers expected to grace the subscriber roles at most MSOs, testing and monitoring the myriad VoIP elements integrated into a network can be a heavy burden.

"Network congestion for short periods of time is a problem, and some packets are dropped as a result. How do you measure that distribution? We've built a conceptual model to address that and the echo issue, which is more obvious in a VoIP network. But voice is very sensitive and needs more good test tools," says Alan Clark, president and CEO of Telchemy Inc., a provider of VoIP performance management technology that integrated its VoIP analysis and monitoring technology with a range of Acterna VoIP products.

Yet certain testing fundamentals remain, and maintaining a healthy network tops the list. Concludes Field of Comcast: "Monitoring HFC plant is the key before we can deploy VoIP or any quality product. We're trying to create fingerprints in a dynamic network that's changing, and we're doing lots of work to understand performance. Interoperability was the challenge with circuit switched, and that's the challenge now with VoIP. It's just that the path is more complex."

Just where the VoIP test and monitoring path leads will likely depend on which players can meld together an all-encompassing test solution that will meet the rigid requirements for QoS, PacketCable and other vital elements specific to VoIP.

Most experts agree, however, that for the foreseeable future, maintaining a healthy HFC network, while integrating key VoIP testing and monitoring components, including field analyzers, network probes, et al, will be the best-of-class strategy.

Concludes Carvazos: "Each network is different. The more complex it is, the more need there is for testing and monitoring equipment."


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