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VoIP PERFORMANCE TESTING TOOLS

"There will always be a need for manual testing"

Terry Caterisano (quoted in Linask).

VoIP Services

Conducting automated and manual tests on Voice over Internet Protocol (VoIP) can help VoIP service providers circumvent expensive and embarrassing problems as well as support their commitment to ensure their network delivers acceptable call quality and non-stop availability. With some VoIP services, one may only call other individuals using the same service. Other VoIP services, albeit, may permit one to phone any local, long distance, mobile, and/or international numbers. While various VoIP services work only over a computer or a particular VoIP phone, a number of other services permit a person to make calls with a traditional phone connected to a VoIP adapter. Despite differences, however, VoIP service providers and vendors reportedly routinely test VoIP performance to enhance its performance (Voice-Over-Internet Protocol; Linask; VoIP Performance Testing...).

During the research paper, the writer presents a sampling of several technical and business sources to relate relevant reflections regarding VoIP performance tools. The writer also asserts, as the quote at the start of this paper indicates, that in testing, the person, more than any system in both automatic and manual processes, proves to be the most valuable component.

VoIP and Testing

VoIP depicts a technology that enables one to use a broadband Internet connection rather than a regular (or analog) phone line to make voice calls. Benefits from VoIP include reduction of telecom costs, management of one network instead of two, simplified provisioning of services to remote locations, and the ability to deploy a new generation of converged applications (Voice-over-IP (VoIP) and Network Performance; Linask). In the book, Voip Voice Over IP 100 Success Secrets - 100 Most Asked Questions on Voip Phones, Providers and Services, Marion Tracey relates four reasons most companies subscribe to VoIP services. These include: 1) VoIP proves cost effective as it circumvents expensive per minute long distance calls; 2) Many professionals who travel regularly consider VoIP more suitable to their lifestyle: 3) as VoIP enables the subscriber to utilize Real-time and audio and video conferencing, the user may avoid having to organize face-to-face business meetings; 4) VoIP provides flexibility that in turn improves productivity as employees may eat integrate their mail and phone services via a solitary application.

VoIP network performance testing can indicate the division between a VoIP system operating at a high level and a weak system functioning so poorly that customers could transfer their business to competitors. Testing for protocol and services interworking, performance, capacity, network strain, and other factors proves vital to identify and address any glitches or shortcomings affecting VoIP (Voice-over-IP (VoIP) and Network Performance; Linask). To avoid costly and embarrassing problems, service providers and vendors need to implement testing not only prior to the time they present the new product or solution to the user community, but also during the employment of the product or solution.

VoIP testing consists of two distinct areas: 1) Pre-deployment testing and 2) post deployment testing. Pre-deployment testing reduces potential risks and problems by allowing one to run realistic and worst-case scenario testing under controlled circumstances (Voice-over-IP (VoIP) and Network Performance). In the article, "VoIP Testing Made Easy with Automation," Erik Linask, the editorial director of TMC, a Web-based information provider with approximately 2,000,000 monthly visitors, asserts that service providers without their own testing labs or technicians may secure testing services from a substantial number of test solution vendors which provide the equipment and software required to effectively test VoIP performance. Unfortunately, Linask stresses, none of the test solution vendors can perform all the basic, essential testing functions well.

Linask reports that Terry Caterisano, President and CEO of CallMation, one test solution vendor, asserts that although some test solution vendors excel in testing call generation, they may be inferior in feature testing. Others may prove superior when testing features, yet lack the ability to test voice quality. Over time, a service provider or vendor may need to utilize a variety of test equipment from a number of various vendors in test labs. The following seven best practices help ensure the service provider or vendor experiences a risk-free VoIP deployment and ongoing processing of VoIP.

1. Replicate network conditions to identify VoIP scenarios

2. Duplicate real-world scenarios in a testing lab to instigate VoIP services

3. Evaluate VoIP call quality

4. Confirm in a testing lab

5. To corroborate quality remedies, repeat the above four steps

6. Conduct pre-deployment acceptance testing

7. Routinely apply best practices (VoIP performance testing fundamentals).

One prominent VoIP performance tool, a virtual network test bed primarily proves useful for taking risk out of both initial VoIP deployment and long-term VoIP implementation. Basically, a test bed, situated in a lab environment, permits application developers, quality assurance (QA) specialists, network managers and other it staff to replicate, securitize and investigate the current or planned production network applications' behavior/s. This type test bed, vital for modeling VoIP performance in the production environment, validates vendor claims, compares alternative solutions, experiments with proposed network enhancements, and experiences the call quality the planned VoIP implementation will deliver (VoIP performance testing fundamentals).

During the VoIP testing process, traffic generation, network traffic analysis and IP network recreation serve as vital tools that can help identify and decrease risk to effective VoIP service. Concerns in testing include apparent voice quality on VoIP systems, severely affected by packet loss, packet delay and jitter which comprise variable packet arrival times. The solution for these factors, inherent to any packet-based system, includes altering networks and assigning higher priority to VoIP traffic. In addition to potentially proving to constitute a time-consuming and troublesome process, altering the parameters of a live network may also negatively affect the performance of other applications. Another option involves utilizing a network simulator. The network simulator enables one to exactly model the target network and consequently observe the effect of changing key factors like routing, link speeds, and priorities (Voice-over-IP (VoIP) and network performance).

The deployment of VoIP testing stimulates the following two proposal questions:

1. Does the VoIP system deliver adequate perceived voice quality?

2. Does the VoIP application affect the performance of other applications?

Voice, by definition, exists as analogue in nature, while voice quality proves highly subjective. One network may deliver a number of different perceptions of quality for various voice types. When measuring voice quality, tests involve two essential advances, analogue and digital. An analogue voice quality tester produces a real voice call across a network and weighs it against the received call with the reference call. A digital voice quality tester analyzes the packet data stream containing the VoIP data and measures packet loss, packet delay and packet jitter. The tester then uses the ensuring information I to calculate the likely voice quality, expressed as predictive Mean Opinion Score (MOS) (Voice-over-IP (VoIP) and network performance).

When the VoIP voice quality proves inferior, the service provider, vendor or customer may need to test cabling channels as over time, moving, adding and/or changing cables can contribute to their degradation. Circuits may also contribute to substandard voice and call quality. Other quality challenges may require a remote monitoring (RMON) tool to track VoIP performance. RMON, a network management term constitutes a "specification for collecting and reporting advanced network activity data. Data collected using RMON can be used to analyze remote network performance, topology, faults, departmental usage (for accounting) and protocols" (RMON, RMON Section). The Internet Engineering Task Force (IETF) developed RMON to support monitoring and protocol analysis of Ethernet and Token- Ring LANs. RMON depicts the industry standard specification that furnishes to a great extent of the functionality contemporary proprietary network analyzers and protocol analyzers offer.

According to Linask, Caterisano stresses that no standards for testing VoIP currently exist. The majority of provide a level of automation and remote control over VoIP devices, but only for basic tasks, like loading a script, initiating its start, stopping the script, and capturing results. No consistency, albeit, exists between vendors regarding how they facilitate those capabilities. Even though the need for manual testing will always exist, automation can offload 50% of the work the tester may perform daily onto a structure that runs tests overnight and on weekends.

When a network server or vendor plans for VoIP, the planner should expect the peak in use to occur all the time. If peak service scenarios are not pre-planned, when heavy processing does occur, the provider or vendor's voice signal will degrade. In addition, examining buffer space and discards on active electronics proves vital. As a function, switches discard packets. When the buffers exceed their full capacity, they drop packets and require the sender retransmit, an adverse feature for voice. Even though one may set up VLANs and priority, overloaded gear will prove futile. Instead, one will need to check discards on any uplink port and any port generally attached (for example in the IP switch) (VoIP performance testing fundamentals).

In addition, the tester may discover a number of errors in SNMP data that also merit investigation. Bit errors, which may be perceived as InErrors and OutErrors prove most significant. Some manageable systems will not permit one to drill down further into the error state, albeit, some systems allow this action and consequently enhance the troubleshooting process. When these errors surface, one should initially test the cabling channel connected on that port as well as confirm the installation of the latest revision of software on the system and the updated, current status of the firmware calibration. The tester also needs to ensure interfaces and/or patch cords are relatively new. As each implements a limited number of mating cycles, a specific channel may appear to be malfunction when it is performing correctly (VoIP performance testing fundamentals).

The tester also needs to examine duplex configurations as having full duplex links duplex proves vital to performance. Mismatches and/or channels auto-negotiated to half duplex will further limit VoIP operations. Half duplex links may result from a hard setting in either the switch or at the workstation as well as faulty cabling, including channels exceeding the maximum distance designated for VoIP performance. When the tester corrects errors, he will need to schedule a following network pulse in 30 days. This time element allows for things as month-end processing and other functions that do not occur daily (VoIP performance testing fundamentals).

In the article, "Operation: VoIP: Testing and Monitoring Are Complex. But Key for Solid

Results," Craig Kuhl explains that VoIP testing includes the following four stages/segments

1. Research and Development test equipment

2. Manufacturing test equipment

3. Installation and maintenance test equipment

4. Monitoring test equipment (Kuhl, ¶12).

Kull asserts that the ultimate criteria to ensure the peak VoIP Quality of Service (QoS), reliability and performance proves challenging. As VoIP constitutes a new venture for the cable industry, it mandates fresh skill sets, tools, equipment as well as innovative corporate engineering and perceptions. In response to the Yankee Group's projection that the growing VoIP business would reach 18 million subscribers by 2009, the vendor community designed and administered a number of crucial tests to pass or fail an IP-enabled voice network. Cable VoIP, like broadband VoIP, comprises a legitimate business. This contributes to the expectation that competition between service providers will significantly increase during the next 10 years. Critical tests, albeit, will need to continue to help ensure efficient service. As this growth occurs, service providers and vendors will need to implement even more test and monitoring equipment (tools), particularly in areas like troubleshooting (Kuhl).