The VoIP management challenge

Enterprise network managers are implementing VoIP, but how are they managing these installations? Here are four tools to simplify the task

DA-3400, it manages them in a slightly easier and certainly more accessible user interface. The Brix System is more flexible, but the OptiView has had more time to win the hearts and minds of the same network managers who are now implementing VoIP, especially those from midsize companies looking to maximize their IT budgets.

Spirent Abacus 5000

Unlike the other tools in this roundup, Spirent's Abacus 5000 isn't intended to measure VoIP network quality. Instead, it is intended for manufacturers of VoIP equipment to measure just how well their products meet industry standards. The type of VoIP gear it's capable of testing ranges from small VoIP appliances all the way up to large, telco-oriented VoIP PBX and switching products.

Like most of Spirent's products, the Abacus 5000 comes as a stand-alone box equipped with an expandable port chassis to accommodate multiple test configurations. All hardware is controlled by a dedicated software suite running on an attached workstation using Windows 2000 or Windows XP Pro.

Our only gripe with the Abacus' software is that each phase of a test setup opened a new window, resulting in so many simultaneous windows that a multiheaded video setup would have been useful. Having additional screen real estate can go a long way toward making sure you don't miss a screen squashed at the bottom of the mosh pit.

Because the most important measurement is the user's experience, the Abacus approach to measuring call quality is more real-world than the simple MOS scores used by many other systems. Instead of just measuring through a simulated phone, Spirent has an adapter that replaces the phone's audio handset (the earpiece) with an electrical interface so that it can send and receive real WAV files.

Spirent goes a bit further and uses various WAV file recordings of different people speaking to measure voice quality over a wide range of users, instead of relying on the so-called "95th percentile human" theoretical measurement used by other test suites.

Straight standard-compliance and product testing is hardly the device's limit. A wide variety of accessories turn Abacus into an all-purpose VoIP tool -- as long as you're willing to spend the additional retrofitting time and, of course, the bucks. You can attach POTS interfaces to be configured as FXO (Foreign Exchange Office), FXS (Foreign Exchange Subscriber), T1/E1 Ethernet, or a multitude of other telco-standard interfaces.

Calls are simulated either through the telco interfaces or by creating simulated VoIP handsets (SIP, MGCP, H.323) with variable ramp up times. This is valuable data considering that every time a VoIP handset is turned on, it must obtain its configuration from the proxy server. If call accounting is turned on, then the handset must also create entries in a database.

Thus, being able to vary the ramp-up rate allows the Abacus to more realistically simulate the real world. It's impossible to simultaneously power up 200 or more phones, which is why this ability to ramp up the call rate exists. You can also control a call's start, end, and duration in addition to the type of voice or sound played back over the link.

Another interesting Abacus feature is trunking. Trunking will aggregate a large number of calls to the PBX as if they were coming in from a gateway or T1/E1 channelized telco circuit, or as if a number of calls were coming in from another PBX over the Ethernet. That means the Abacus can test a large number of phones over a variety of links, and it can test them in a variety of implementations.

Abacus' only catch is that it assumes that any products it tests adhere strictly to published standards. But as we discovered during InfoWorld's recent VoIP PBX test, the VoIP industry rarely does this.

We used the Abacus as the central test device in that review of four VoIP PBX products. Three of those four PBXs had tweaked their implementation of the SIP or H.323 protocol enough to flummox the Abacus and require dedicated fix upgrades from Spirent's technical staff. The device that stuck strictly to the SIP standard easily completed all the Abacus' tests.

This standards-tweaking forced Spirent to spend an amazing amount of engineer time working with each VoIP vendor in our PBX review so that each would handle exceptions. Although this sounds like a real problem, keep in mind that the Abacus seems to have been designed by telco engineers, and the telco world is built around the strict implementation of standards.

Still, standards-tweaking and extra engineering fixes can't continue to be the norm. Extending simple protocols such as SIP and H.323 may provide custom features, but the VoIP marketplace can't allow noninterchangeable, nonstandard phone systems for much longer. The effort required to integrate systems is simply too big a financial burden for service providers or large enterprises to bear.

Even with this caveat, the Abacus isn't designed for enterprise VoIP network management. Although it's certainly flexible enough to manage such tasks, its price point and engineering focus just don't extend in that direction. This is a VoIP device testing tool for telcos and at that job, it truly excels.

InfoWorld Scorecard
Features (25.0%)
Performance (25.0%)
Value (10.0%)
Setup (10.0%)
Standards (15.0%)
Scalability (15.0%)
Overall Score (100%)
Acterna DA-3400 Data Network Analyzer 8.0 8.0 7.0 8.0 6.0 8.0 7.6
Brix System 8.0 8.0 7.0 7.0 7.0 9.0 7.8
Fluke Networks OptiView Protocol Expert Plus 8.0 7.0 8.0 8.0 9.0 7.0 7.8
Spirent Abacus 5000 8.0 8.0 7.0 7.0 5.0 8.0 7.4
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