Network Assessments
for IP Services/VoIP
Case Studies
There are many corporations today who are looking for
the cost reducing opportunities of new IP services.
Additionally, there is new competition in the
communications service provider market due to the new
technical opportunities that allow converged voice and
data services over cable networks. All of these situations
have something in common: People are working with a
relatively new technology, in which problems must be
identified and solved. In all cases, the technology is a
means to an end- a means to deliver cost effective, high
quality private or commercial service to their customers.
Agilent has had the opportunity to work with these
customers and lend valuable test and simulation expertise
to these pioneers through our Network Assessment
Services. Following, are three Case Studies for VoIP
installations that proved to be successful. All company
names are omitted to honor customer privacy.
No matter where a customer is in the design cycle for
deploying network services, they have three options to get
there.
1.
Deploy the equipment
and service with in
house staff that need
time to climb a learning
curve and must
purchase/rent test tools
they may not use
frequently after
deployment.
2.
Hire an equipment
vendor or system
integrator and trust that
the vendor’s
performance claims
about their solution are
accurate.
3.
Combine option one or
two with an expert,
objective third party
who can test the design,
verify live performance,
and isolate faults.
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Study #1
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Study #2
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Cable TV VoIP
Service Provider
Case Study #3
Petroleum Corporation VoIP Solutions Case Study #1
Customer Profile
Large Multi-National Petroleum Company, with remote field operations
Customer Problem
Phase I : Fault isolation, gaining vendor cooperation
to resolve problems
Phase II: Finalizing network service design and
meeting quality of service requirements
Agilent Services Provided
Phase I : Live Performance Verification
Phase II: Benchmark Assessment, Proof of Concept
Testing, Live Performance Verification
Background
This Petroleum Corporation needed extra network capacity. Because their employees work in extremely remote locations, their communications capability is critical to their productivity and sanity. In this case, their employees were located in the Arctic Circle and needed to communicate with the office in Anchorage, Alaska. Voice and e-mail communications can be the only form of communication these employees have during work assignments away from home. Their engineers utilize CAD programs and databases of research data, which produce files that need large quantities of bandwidth to be transmitted over the network.
Leasing T1 lines in such remote locations is extremely expensive because a line must typically be installed for that customer alone. There is little infrastructure to leverage. Maximizing the utilization of their existing bandwidth is their best option for providing cost-effective service to their employees. The Petroleum Company decided to deploy voice over Internet protocol or VoIP to address this need. Along the way, Agilent helped them determine problems, verify the actual performance of the network equipment and deploy a solution.
Phase I
The Petroleum Company had previously selected a vendor and installed VoIP service within an existing data network between their main office and a remote field office. They experienced quality of service problems and they were unable to get the support they needed from their Network Equipment Vendor. Their Network Equipment Vendor believed that the equipment was performing correctly and maintained that it was configured appropriately. Meanwhile, their employees complained about terrible voice quality and slow network performance.
As a result, their employees bypassed the cheaper internal VoIP network and used the more expensive circuit switched internal network for long distance communication. The circuit switched network was already congested and the additional calls generated by the bypass of the VoIP network exacerbated the problem. The Petroleum Company was still paying high fees for long-distance calls and their new investment was not paying off.
Helen Wetters of Team Inc, a Manufacturers Rep firm, worked with the customer to understand the problem. Team, Inc. brought in Agilent Consultants to help resolve the problem.
The Agilent Consulting team initiated a meeting that brought the customer and the vendor together to discuss the problem and review the testing
methodology. The discussion helped the vendor understand the impact of the problem to the customer. They became engaged in trying to resolve the problem. Initially, a half duplex interface was discovered in a router that should have had a full duplex interface. The half duplex interface prevented
communications from traveling in both directions at once, which lead to poor voice quality caused by delays and dropped packets. After the replacement of the half duplex interface, the voice quality was tested.
The majority of the quality issues were resolved.
A. Existing Network Baseline: Agilent proceeded to work with the customer to assess voice quality. A baseline was established for the existing circuit switched network. This benchmark was used to assure that the VoIP voice quality would be on par with what the employees expected from the old network. Voice quality measurements of the existing network included PAMS, PSQM and signal loss. The signal loss measurement showed correct signal attenuation in one
direction, but not the other. This gave the customer an opportunity to fix this problem before it became an issue.
B. VoIP Network Performance Assessment for the New Network: Agilent tested the voice quality (PAMS and PSQM) with a single VoIP call. Voice quality was slightly better than the existing network. The signal loss measurements revealed incorrect attenuation in both call directions. Agilent then tested for voice quality with the maximum call load to understand the effects of call volume on voice quality. No voice quality
degradation was observed. Determining the effects of data traffic loading was the next step. IP data traffic was generated across the network to achieve a WAN utilization of 100%. Voice quality was maintained. Dynamic bandwidth
allocation allows data traffic and voice calls to share bandwidth. An allocation scheme is set up to provide
priority to voice at times when both voice and data traffic exists. If all voice traffic is absent, the data traffic should receive 100% allocation of the bandwidth. In this case, the bandwidth allocated to voice was not defaulting back to data. Bandwidth allocated to voice was wasted at any point when voice was not 100% active. The customer learned that the shared voice/data IP solution was not the best economic choice for them.
Result
Although the voice quality of the VoIP network was slightly superior to their existing network, they chose not to deploy a mixed voice/data network.
In the end, the consulting engagement saved the customer from deploying solutions that would not have provided the advertised savings.
Phase II
The oil company was pleased with the service they had received from Agilent. Six months later, they asked Agilent to help them evaluate a voice only VoIP network. The petroleum company was redesigning their network and brought Agilent in during the early phases of design. The new network was designed to allow three remote sites in the Alaskan North Slope to communicate over one T1 line to Anchorage, Alaska. The company selected a leading network manufacturers’
equipment for which they wanted performance verification. The vendor claimed that 125 VoIP calls could be placed over a single T1 circuit with the use of their routing technology. Agilent came in to determine how many calls could be executed while maintaining good voice quality.
The voice quality baseline had been established in the previous phase of voice quality testing. Armed with the baseline on boththeir traditional voice network and their prior VoIP trial, engineers set out to model the VoIP voice quality for the new deployment. Signal level
problems were identified and corrected before the network went live. The single call voice quality matched the previous benchmarks. However, the circuit was unable to meet the 125 call load while maintaining good QOS. Agilent determined that the maximum call load was 56 calls or less than half of the
advertised call volume. Once the call volume exceeded the 56 volume load, the QOS would deteriorate such that the employees would hang-up or their call would be dropped. The petroleum customer had two choices:
1. Add more bandwidth
or
2. Restrict the call volume to 56 calls.
Due to the high cost of additional bandwidth, the customer
restricted the call volume. The routers were set up correctly and tested to avoid the problem.
Result
In both these cases, Agilent was able to help the customer make the required assessments, understand their network performance and deploy faster than they could have deployed on their own. The customer avoided the disruption of decreased data speed and poor voice quality, both of which would have been costly problems.
Utility Company VoIP Deployment Case Study #2
Customer Profile
Regional Utility Company in the Southern United States
Customer Problem
Fault isolation and resolution
Agilent Services Provided
Live Performance Verification
Background
A large utility company in South Central United States deployed Voice Over IP (VoIP) for
interoffice communications to 80 locations. Frame Relay was the transport for the existing data network VoIP was added to the existing network to eliminate or reduce long distance charges for interoffice voice communications. The office PBXs were connected to Routers that transported both voice and data to the network. Users complained of voice quality issues and problems. Problems accessing voice mail and other IVR type features were also reported. The Utility Company had spent a large sum of money to implement VoIP but the users bypassed VoIP lines because of unsatisfactory performance. A representative from the utility company raised these issues while talking with an Agilent engineer at the Agilent booth during a trade show. Agilent proposed to identify the source of the problems through a network assessment.
Agilent was hired to assist the company with finding the cause of the problem. Agilent
developed a test plan that involved testing voice quality while monitoring the WAN for packet loss, jitter, utilization, and line errors and to measure signal loss.
Testing proceeded between sites that had reported the most problems. Reported problems
were not observed on the day of testing between Site A and Site B. Utilization of the WAN was low. However, signal loss
measurements uncovered
improper loss and gain setting in the router and PBXs. The router and PBX configuration problems were observed that required correction.
All the reported problems were observed while testing between Site C and Site D. Voice quality would intermittently test poorly. Data traffic was high at site C and saturated the WAN. A high rate of jitter and packet loss was observed when the WAN was saturated. Signal loss was measured and determined to be out of tolerance.
Agilent consultants, the utility company’s data network and voice engineers, and a Network Equipment Manufacturer engineer collaborated on the problems and determined that the routers were configured to give data priority over voice. When heavy data traffic was present, voice quality degraded. Typically, PBX technicians (voice experts) are given instructions for switch pad settings within the PBX when installing line interfaces. The data networking team ordered the installation of the interfaces but failed to provide engineering for the setting of the switch pads.
gain in the routers with the golden ear method-someone listened to the sound and determined the settings. Unfortunately, the golden ear method is not reliable when there are many sites that are
interconnected, such as in this situation where 80 sites were connected to their network.
Result
Agilent recommended a signal level loss plan be devised and implemented to resolve the IVR issue. Agilent also recommended configuring the routers to prioritize voice over data. Plans to resolve the signal levels and voice priority were to be devised and implemented by the customer.
The company was able to gain the benefits of their investment in VoIP and the user complaints were resolved.
Transmission levels had been adjusted by configuring loss and
Cable TV VoIP Service Provider Case Study #3
Customer Profile
Cable Service Provider in the Midwestern United States
Customer Challenge
Deploying Bleeding Edge Commercial VoIP Service Over Cable
Agilent Services Provided
Full Assessment Suite
Background
In 2001, a cable TV provider hired Agilent to perform network diagnostics and analyses to aid in selecting equipment for its pioneering VoIP service offering. The service provider was
evaluating two vendors and they needed a consultant that could be “vendor neutral.” The cable provider planned to select the vendor based on performance. Agilent was able to provide non-biased test results through out multiple phases that allowed the service provider to make an informed choice based on the test results.
Each vendor’s solution provided all the network elements
necessary to provide analog voice service to residential cable TV subscribers over the existing cable TV network. Dial tone was provided to the residence via a cable modem. The cable modem converted analog voice to IP packets that were transported through the cable plant to the cable company’s central office switch or call agent. Calls could be placed to other subscribers within the cable network and to the outside world via the Public Switched Telephone Network (PSTN).
Vendor evaluation was performed in two phases. Phase I tested each vendor’s solution in a lab environment with all testing performed on a closed network.
Phase II would add residential
cable subscribers and the PSTN.
Phase I
Phase I testing consisted of voice
quality testing with the Agilent Voice Quality Tester (VQT), fax transmission testing using the Agilent Telegra Fax Tester, monitoring packet loss with the Agilent IP Telephony Analyzer, and data traffic loading using the Agilent Advisor and Router Tester products. Call feature testing and network element failure simulation were also performed.
Agilent’s Consulting Engineers uncovered unacceptable voice quality, call completion problems, fax transmission issues, and general performance problems that sent both vendors back to the design lab. Neither vendor solution could transport VoIP telephone calls across a cable TV network with service quality comparable to a conventional telephone service provider. Each vendor had a list of problems to resolve before proceeding to
Phase II of the trial. The
vendors benefited by refining their designs and resolving issues before the live trial.
Phase II
Phase II tested the complete
solution that now included a live cable network, the VoIP transport system, and connections to the PSTN. All tests performed in
Phase I were performed again to
verify problem resolution. Voice quality and fax testing were performed from residences located both near to and far from the cable head end equipment.
Agilent analyzed these cable segments for RF loss, noise, and other cable impairments to understand how cable length affected voice quality and fax transmissions.
Agilent Technologies again uncovered issues and problems that neither the vendors nor the customer knew existed. Some problems were resolved during the trail and other problems would have to be resolved in vendor’s laboratories. Detailed reports provided by Agilent Technologies to the cable service provider described the results and facts documented during Phase I and Phase II testing. Reports were issued for each phase and for each vendor. The cable service provider was now faced with the decision to choose one of the vendors, to use another method other than VoIP to transport voice to customer residences, or to abandon the voice service offering. The company chose vendor two because the solution performance was superior.
Pre-Deployment Testing
VoIP over the cable providers network would be deployed in stages. The first installation would be deployed in the region where vendor two’s Phase II was performed because it was known to be ready.
August 2002 was the scheduled launch for the new cable based
Product specifications and descriptions in this document subject to change without notice.
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VoIP service. The company realized the value of Agilent’s Consulting expertise during their vendor selection process. Once the cable provider personnel and network equipment manufacturer engineers considered the network ready for service, the service provider asked Agilent Technologies to verify the
readiness of the new VoIP service. Additional tests were added above and beyond the test suite used in Phase I and Phase II of the design trails. Baseline measurements were taken of the local telephone service provider’s circuits for voice quality, fax performance, and signal level loss in order to gauge the
performance of the VoIP circuits. Security, domestic long distance calls (in excess of 1,500 miles/ 2,400 kilometers), and
international calling were also performed.
Agilent Consultants verified that the network performed
exceptionally well compared to
the networks in the trial. Quality was good. However, Agilent’s consultants found minor and severe network issues that required attention and resolution prior to the final deployment of the VoIP service to customers. For example, the network was vulnerable to hackers. A network element failure simulation uncovered a routing issue that crippled the network and signal levels were out of tolerance. Advertised call features did not work according to the
documentation furnished to the cable provider’s customers, and other minor problems were found and resolved.
Result:
While these issues delayed the final deployment of the network. Resolution of the major issues was critical to the cable TV service provider’s customer satisfaction and customer credibility. They launched a more secure and reliable network with confidence.
