Software Roots Out VOIP Trouble

 
 
By Andrew Garcia  |  Posted 2005-07-11
 
 
 

Software Roots Out VOIP Trouble


Apparent Networks Inc.s AppareNet Voice Professional 2.6 provides surprisingly accurate, in-depth information on network performance characteristics, rooting out many common misconfigurations and errors that go unnoticed in data-only networks but can easily sink real-time applications such as VOIP.



Click here to read the full review of AppareNet Voice Professional 2.6.

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Apparent Networks Inc.s AppareNet Voice Professional 2.6 provides surprisingly accurate, in-depth information on network performance characteristics, rooting out many common misconfigurations and errors that go unnoticed in data-only networks but can easily sink real-time applications such as VOIP.

Voice Professionals intelligent diagnostic algorithms identify duplex mismatches, ineffective or outdated network drivers, and network congestion or bottlenecks. In addition, the algorithms can predict voice quality under varying simultaneous call loads.

The software uses short bursts of UDP (User Datagram Protocol) and ICMP (Internet Control Message Protocol) traffic between an integrated sequencer and any remote host on the WAN. Because Voice Professional doesnt require voice-over-IP administrators to deploy large numbers of endpoints throughout the network, it does not unduly stress the network.

Click here to read more about how new VOIP performance assessment tools can help pre-empt problems.

Voice Professional 2.6, released in May, costs $15,000 to deploy on a single computer. Voice Professional can be installed on Microsoft Corp. Windows Server 2003, Windows XP with Service Pack 1 or Windows 2000 machines.

A Voice Professional installation consists of the AppareNet server application, a Microsoft SQL Server 2000 Desktop Engine database, a Business Objects S.A. Crystal Reports 9-based reporting engine and a sequencer (a small software component that generates traffic and records the response characteristics)—all of which are installed on a single machine.

Tests can be run immediately or scheduled via the Batch function. To kick off a test, we selected the remote host or range of hosts we wished to test.

The amount of traffic generated by Voice Professional is quite low, so we could simultaneously conduct several tests of different devices. For more accurate results, we could change the number of test iterations and the numbers of packets sent in each burst.

Voice Professional allowed us to test devices under a variety of call conditions. We could select from a roster of common compression codecs, including G.711, G.723, G.729 and GSM (Global System for Mobile Communications), or we could determine ToS (Type of Service) settings. We could vary call load as well, choosing to simulate anywhere from one call to 25 concurrent ones.

Our test results detected lost packets and measured MTU (Maximum Transmission Unit), bandwidth, utilization levels, propagation delay, round-trip times and packet jitter. Our test results also estimated values for best, worst and average measured MOS (mean Opinion score) values—not only for the tested target but for all intermediate hops in a routed network as well.

We liked Voice Professionals ability to step through the number of simultaneously active calls in order to gauge the threshold at which the network gets saturated and MOS values plummet.

Each detected error is linked to Voice Professionals library of help messages, which provides a summary and detailed explanations of the issue as well as a list of recommended actions for remediation.

Small differences in reported MOS scores might seem esoteric to all but the most grizzled voice assessment veterans, so Voice Professional includes a voice- sample playback feature. Taking a canned voice sample, Voice Professional applies the call distortion commensurate with the predicted MOS, allowing administrators to hear what the call would actually sound like.

Although the feature will lose importance as administrators become more familiar with voice management, it provides a great service to the less initiated.

The Crystal Reports-based reporting engine is functional, although it is not as intuitive as wed like. Finding the right results can be a little complicated. Test results are organized on-screen according to Test ID numbers that are sequentially generated as tests are created and run—and with a large number of tests, it was hard to zero in on the one we wanted.

However, the search function did allow us to perform granular searches according to administrator, date, target and findings.

The biggest drawback to using Voice Professional is that all tests must use the integrated sequencer as one endpoint. Because enterprise voice networks are often large, multisite endeavors, it would be preferable to have the option to kick off tests between sites remote to the AppareNet server.

Voice Professional does offer the ability to send sequencers to remote computers, so users may quickly install the software, and administrators can script a test to run between two remote systems. However, at the time of testing, Voice Professionals licensing does not allow the results of these tests to be imported back into the AppareNet server for analysis.

Because this feature is available with Apparent Networks data-only testing products, we expect it to be enabled in Voice Professional in the near future.

Next page: Evaluation Shortlist: Related Products.

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Evaluation Shortlist

Ixias IxChariot A central console manages an army of endpoints, which generate synthetic voice traffic to analyze jitter, delay and other metrics. Well regarded for data and throughput testing capabilities but wont provide much in the way of diagnostics (www.ixiacom.com)

NetIQ Corp.s Vivinet Assessor Similar in architecture to IxChariot, Vivinet Assessor integrates with Vivinet Diagnostics to pinpoint issues with call quality (www.netiq.com)

Telchemy Inc.s VQmon/EP A distributed voice testing product with a twist—the agents are embedded in end-user VOIP devices through OEM agreements with hardware manufacturers (www.telchemy.com)

Technical Analyst Andrew Garcia can be reached at andrew_garcia@ziffdavis.com.

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