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New VoIP products seem to come to market daily, resulting in a dizzying array of choices. Enterprises and service providers need to be able to measure the impact a particular VoIP product will have on their network. What audio and video codecs are supported? Does it support SIP or H.323 and is it interoperable with other vendors� SIP or H.323 products? What about packet loss, jitter, and latency? How many audio or video calls can the network handle? To answer questions like these, a VoIP testing product such as Delta Protocol Test Solutions H.323 and SIP protocol analyzer/emulator is required. The product consists of two separate software programs called the Emulator and the Voice and Video over IP Protocol Analyzer. Also, although we didn�t examine this, we should point out that Delta Protocol Testing Solutions features highly scalable H.323 and SIP Bulk Call Generator programs.
Their turnkey testing and protocol analysis solution can test Internet telephony (voice and video over IP and Internet fax) as well as to traditional video teleconferencing, since many of the standards are common to both. It can test and diagnosis VoIP protocols with full packet decoding, including H.323, SIP, SDP, MGCP, SGCP as well as video/data conferencing standards that include H.320, H.323, H.324, T.120, H.261, and H.263. TMC Labs tested the H.323 Analyzer/Emulator program using several H.323 NetMeeting clients.
We first examined the Video over IP Protocol Analyzer program, which can be used in verification testing of products under development. Delta Protocol Testing has great experience in codecs, particularly with their history in videoconferencing in proprietary military applications. Their software was designed as the �base� reference point that is 100 percent compliant with the H.323 (and SIP) standards. As such, not only can it perform stress testing on connected equipment, it can also see if a device is 100 percent compliant with the appropriate standard. Thus, interoperability testing can be performed and problem areas in the communication protocol between multiple endpoints can be isolated. It can provide any specific test sequence, or operate in a passive, listen-only monitor mode between equipments engaged in a VoIP or video call. The best analogy would be to think of a typical network analyzer, which monitors all types of network traffic for troubleshooting. Delta Protocol�s product merely takes a subset of the LAN traffic only listening in on VoIP and video traffic.
We made some NetMeeting-to-NetMeeting endpoint calls and used the Analyzer to monitor and analyze the traffic. The Analyzer auto-discovered IP addresses communicating on the LAN allowing us to pick the Source and Destination IP addresses from drop-down boxes to monitor/analyze. We could also set the Source IP address to a single IP address and the destination to �All� to monitor all traffic from/to the single IP address.
We ran some of the QoS graphs and reports to determine how well this product analyzes VoIP traffic. One of the graphs (called Bandwidth by Media) shows a pie chart breaking out the various audio and video codecs seen on the LAN, i.e. H.263, G.723, G.711, etc. Several useful real-time QoS graphs are included with the product, including RTP Measurements, Bandwidth by Media vs. Total Bandwidth, Total Bandwidth by IP address vs. Total Bandwidth, and IP connections vs. Jitter.
We purposely set our test 10BaseT network to a theoretical limit of just 20,000 because the VoIP traffic was several factors smaller than the overall network bandwidth, resulting in VoIP bars that were merely lines.
Essentially by reducing the theoretical limit, we were �zooming� in on the graph so we could show the VoIP traffic better. In our test, we had four NetMeeting sessions. Two were connected using G.723 and two were connected using Ulaw (G.711). It makes sense that the Ulaw took up much more bandwidth since it not compressed like G.723. At the time the graph was captured, we weren�t transmitting video, or the H.263 would no doubt be the largest bar on the graph.
Although having real-time graphs that auto-updates every half-second or so was a nice feature, most administrators would probably like to be able to pinpoint VoIP problems that occurred in the past. Thus, we�d like to see a more comprehensive graphing capability that lets you select a date/time range for graphing historical VoIP data.
In addition to analyzing simple point-to-point VoIP endpoints, you can analyze performance and protocol exchange through gateways connecting packet-switched and circuit-switched networks. Using the Analyzer you can also compare vendors� video codec performance. The video analyzer checks bit stream syntax and measures codec performance. A continuous real-time histogram of video code types is displayed, and performance including frame rate is calculated.
Next, we tested the Emulator, which is able to both receive and make outbound H.323 calls. We simply added an IP address of a NetMeeting client running on the LAN, set the test to run for 300 seconds, configured various other settings and then clicked Start Call. We answered the call from the NetMeeting client and were immediately presented not only with audio messages from the Emulator, but a video test consisting of various moving shapes and colors was also transmitted. We could have configured dozens of simultaneous test calls. Up to 150 audio calls only and 50-60 video calls are supported and up to 1,000 gatekeeper registrations. Using the recently released Bulk Call Generator program, up to 10,000 simultaneous gatekeeper registrations is supported.
Overall, both programs were fairly easy to use even though the programs have very detailed configuration screens with various parameters and settings. Fortunately, the
programs do have default settings that make sense in most typical testing scenarios.
FEATURES
Voice and Video over IP Protocol Analyzer:
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Provides complete disassembly, decoding and display of all major standard protocols.
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Packet throughput summary (by media type, source, address).
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Measure packet delay, lost packets, packet jitter,
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High capacity rackmount, mid-tower, and portable workstation.
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RS449, ISDN, PSTN and LAN Network interfaces.
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Optional H.261 codec with camera for producing live test data.
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Sends a multiplexed bit stream of audio, video, and data to the endpoint under test.
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Receives and de-multiplexes the data from the endpoint(s) under test and translates the separate bit streams into user-readable codes.
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Detailed displays with break point event processing.
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Captures and analyzes each protocol layer of the call.
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Displays summaries of key events during a connection.
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Real-time audio playback of captured data.
Emulator 323.
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Multiple call stream generation over.
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1 to 8 10/100 LAN Interfaces.
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H.323v4 with Faststart and Tunneling.
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Build call profiles through a GUI.
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Call profiles are stored for future use.
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Variable call duration and call start delay.
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Originate and answer calls.
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1000 registrations with a Gatekeeper.
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Inject packet jitter and errors.
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Selectable audio and video packet output.
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Detailed status log created.
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Displays call setup/tear down progress.
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Reporting of pass/fail progress for all call activity.
ROOM FOR IMPROVEMENT
It took some time getting used to OS/2, which affected the Usability and GUI ratings for this product, so we�d certainly like to see a Windows-based product if technically possible. Even still, there were some interface designs of the program that could be improved upon even on the OS/2 platform. Perhaps some included benchmark metrics would be useful as well so that a comparison can be made against known expected metrics. As mentioned earlier, we�d like to see a more comprehensive graphing capability that lets you select a date/time range for graphing historical VoIP data. Also, we�d like the ability to export the packet data as a CSV file so we could bring it into Crystal Reports, Excel, or another reporting/graphing program. Delta Protocol mentioned they are adding this capability shortly.
CONCLUSION
Delta Protocol Testing Solutions analyzer and emulator software can accelerate the testing and verification process for new products in development, pre-qualify networks for VoIP applications, and help support engineers in performing interoperability testing with other vendors. This product is also perfect for mission critical environments, such as the carrier and service provider space to monitor, troubleshoot, and diagnose problems with VoIP applications on the network. Although the product can use some �polishing� and refinement on the graphical user interface and usability, TMC Labs wouldn�t hesitate to recommend this product.
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