VoIP Archives - Telnet Networks

How To Monitor VoIP Performance In The Real World

It’s one of the most dreaded calls to get for an IT staff member – the one where a user complains about the quality of their VoIP call or video conference. The terms used to describe the problem are reminiscent of a person who brings their car in for service because of a strange sound “ I hear a crackle”, or “it sounds like the other person is in a tunnel” or “I could only hear every other word – and then the call dropped”. None of these are good, and unfortunately, they are all very hard to diagnose.

As an IT professional, we are used to solving problems. We are comfortable in a binary world, something works or it doesn’t and when it doesn’t, we fix the issue so that it does. When a server or application is unavailable, we can usually diagnose and fix the issue and then it works again. But, with VoIP and Video, the situation is not so cut and dried. It’s rare that the phone doesn’t work at all – it usually “works” i.e the phone can make and receive calls, but often the problems are more nuanced; the user is unhappy with the “experience” of the connection. It’s the difference between having a bad meal and the restaurant being closed.

In the world of VoIP, this situation has even been mathematically described (leave it to engineers to come up with a formula). It is called a Mean Opinion Score (MOS) and is used to provide a data point which represents how a user “feels” about the quality of a call. The rating system looks like this:

Today, the MOS score is accepted as the main standard by which the quality of VoIP calls are measured. There are conditional factors that go into what makes an “OK” MOS score which take into account (among other things) the CODEC which is used in the call. As a rule of thumb, any MOS score below ~3.7 is considered a problem worth investigating, and anything consistently below 2.0 is real issue. *(many organizations use a different # other than 3.7, but it is usually pretty close to this). The main factors which go into generating this score come from 3 KPI’s

Loss
Jitter
Latency / Delay

So, in order to try and bring some rigor to monitoring VoIP quality on a network (and get to the issues before the users get to you) network staff need to monitor the MOS score for VoIP calls. In the real world there are at least three (separate) ways of doing this:

1) The “ACTUAL” MOS score from live calls based on reports from the VoIP endpoints

Some VoIP phones will actually perform measurements of the critical KPI’s (Loss, Jitter, and Latency) and send reports of the call quality to a Call Manager or other server. Most commonly this information is transmitted using the Real Time Control Protocol (RTCP) and may also include RTCP XR (for eXtended Report) data which can provide additional information like Signal to Noise Ratio and Echo level. Support for RTCP / RTCP XR is highly dependent on the phone system being used and in particular the handset being used. If your VoIP system does support RTCP / RTCP XR you will still need a method of capturing and reporting / alarming on the data provided.

2) The “PREDICTED” MOS score based on network quality metrics from a synthetic test call.

Instead of waiting for the phones to tell you there is a problem, many network managers implement a testing system which makes periodic synthetic calls on the network and then gathers the KPI’s from those calls. Generally, this type of testing takes place completely outside of the VoIP phone system and uses vendor software to replicate an endpoint. The software is installed at critical ends of a test path and then the endpoints “call” each other (by sending an RTP stream from one endpoint to another). These systems should be able to exactly mimic the live VoIP system in terms of CODEC used and QoS tagging etc so that the test frames are passed through the network in exactly the same way that a “real” VoIP call would be. These systems can then “predict” the Quality of experience that the network is providing at that moment.

3) The “ACTUAL” MOS score bases on a passive analysis of the live packets on the network.

This is where a passive “probe” product is put into the network and “sniffs” the VoIP calls. It can then inspect that traffic and create a MOS score or other metrics which is useful to determine the current quality of service being experienced by users. This method removes any need for support from the VoIP system and also does not require the network to handle additional test data, but does have some drawbacks as this method can be expensive and may have trouble accurately reading any encrypted VoIP traffic.

Which is best? Well, they both all have their place, and in a perfect world an IT staff would have access to live data and test data in order to troubleshoot an issue. In an even more perfect world, they would be able to correlate that data in real time to other potentially performance impacting information like router / switch performance data and network bandwidth usage (especially on WAN circuits).

In the end, VoIP performance monitoring comes down to having access to all of the critical KPI’s that could be used to diagnose issues and (hopefully) stop users from making that dreaded service call.

Thanks to NMSaaS for the article.

Can Your Analyzer Handle a VoIP Upgrade?

Your looking at doing an upgrade to your VoIP system, as it approaching end of life. But your network has changed substantially since your first deployment, making this an ideal time to investigate new VoIP systems and ensure your existing monitoring solution can keep pace with the upgrade.

Here are 4 critical areas for consideration to determine whether your monitoring tools can keep pace with the new demands of a VoIP upgrade.

1. SUPPORTING MORE THAN ONE IT TEAM:

If you have a voice team and a network team, you might live and breathe packet-level details while the voice is accustomed to metrics like jitter, R-Factor, and MOS.

CAN YOUR NETWORK MONITORING SOLUTION PROVIDE VOIP-SPECIFIC QUALITY ASSESSMENTS PLUS PACKET AND TRANSACTION DETAILS FOR PROBLEM RESOLUTION?

2. ADDRESSING CONFIGURATION CHALLENGES:

In rolling out large VoIP deployment systems, device and system misconfigurations can get the best of even the most experienced network team. To bring VoIP to the desktop ensure you have a proper Network Change and Configiration Management System (NCCM), and run a through pre-deployment evalution and you have the monitoring capabilities to ensure for successful implementation.

3. ISOLATING THE ROOT CAUSE:

If users are or departments are experiencing bad MOS scores. How quickly can you navigate to the source of the problem? Your analyzer should be able to determine whether the call manager or a bad handset might be at the root of your VoIP frustrations? The analyzer should be able to isolate the source of quality problems.

4. SUPPORTING MULTI-VENDOR INSTALLATIONS:

Does you network analyzer provide detailed tracking for multiple VoIP vendors? Your monitoring solution needs to understand how each VoIP system/vendor handles calls. Otherwise you will have to toggle between multiple screens to troubleshoot. Without this support, you may be forced to toggle between multiple screens to troubleshoot or reconcile various quality metrics to assess VoIP performance.

CONCLUSION

Understanding the changes in the environment, ensuring rapid problem isolation, tackling potential configuration challenges, and assessing your solution’s support for multiple vendors are the keys to ensuring a successful rollout.

Network Management Network Monitoring Unified Communications VoIP

The Advancements of VoIP Quality Testing

Industry Analysts say that approximately 85% of today’s networks will require voip quality testing upgrades to their data networks to properly support high-quality VoIP and video traffic.

Organizations are always looking for a way to reduce costs, and that’s why they often try to deploy VoIP by switching voice traffic over to a LAN or WAN links.

In a lot of cases the data networks which the business has chosen handle VoIP traffic accordingly, generally speaking voice traffic is uniquely time sensitive, it cannot be qued and if data grams are lost the conversation can become choppy.

To ensure this doesn’t happen many organizations will conduct a VoIP quality test in the pre and post deplomyent stage.

Pre Deployment testing

There are several steps network engineers can take to ensure VoIP technology can meet expectations. Pre-deployment testing is the first step towards ensuring the network is ready to handle the VoIP traffic.

After the testing process, IT staff should be able to:

Determine the total VoIP traffic the network can handle without audio deprivation.
Discover any configuration errors with the network and VoIP equipment.
Identify and resolve erratic problems that affect network and application performance.
Identify security holes that allow malicious eavesdropping or denial of service.
Guarantee call quality matches user expectations.

Post deployment testing

Places that already have VoIP/video need to constantly and easily monitor the quality of those links to ensure good quality of service. Just because it was fine when you first installed it, doesn’t mean that it is still working well today, or will be tomorrow.

The main objective of post deployment VoIP testing is to measure the quality and standard of the system before you decide to go live with it. This will in return stop people from complaining about poor quality calls.

Post-deployment testing should be done early and often to minimize the cost of fault resolution and also to provide an opportunity to apply lessons learned later on during the installation.

In both pre and post deployment the testing needs to be simple to setup and provide at a glance actionable information including alarms when there is a problem.

Continuous monitoring

In many cases your network changes every day as devices are added or removed, these could include laptops, IP phones or even routers. All of these contribute to the continuous churn of the IP network experience.

A key driving factor for any business is finding any faults before they become a potential hindrance on the company, regular monitoring will eliminate any potential threats.

In this manner, you’ll receive maximum benefit from your VoIP investment. Regular monitoring builds upon all the assessments and testing performed in support of a deployment. You continue to verify key quality metrics of all the devices and the overall IP network health.

If you found this interesting have a look at the recording of one our webinars on this topic, you will get an in-depth look on this topic.

Thanks to NMSaaS for the article.

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Three VoIP Quality Killers

Managing VoIP quality is a constant headache for engineers. Here are some ways to avoid some common problems.

While VoIP has been considered mainstream in the enterprise for the past couple of years, network engineers still face a challenge to ensure consistent VoIP quality. Unplanned or surprise changes to the network can leave end users unhappy and administrators scratching their heads. Even the smallest configuration and setting changes have the potential to immediately and adversely impact applications. One way to guard against performance issues is to use retrospective analysis — long-term packet capture for troubleshooting sporadic network issues — to identify and fix common VoIP quality problems more quickly. Here are some steps to follow:

Assess quality of service. Quality of service (QoS) settings are often the first step to manage VoIP. If QoS settings are not set correctly, the VoIP call doesn’t get passed at the priority it should. That can really affect call quality. Since network devices take care of setting the priority, incorrect QoS tagging can cause the quality of the calls to deteriorate. Customers will call in to figure out why they have one side of a phone conversation that sounds perfect and has a good mean opinion score while the other side is bad. Not having QoS tags properly configured can cause backups in the VoIP traffic, which can cause high jitter. If packets aren’t arriving when they’re supposed to arrive, there will be delays and the call will start sounding choppy.

To pinpoint the source of the problem, it is often necessary to begin at the packet level, using a retrospective network analyzer. A network recorder or advanced probe appliances placed at different points on the network, such as in front of different switches or routers, can collect a massive amount of data. Using different tools within the network analysis application, you can assess the QoS tag settings to determine if they are the same on both ends. If they’re not, this method can help you identify the offending hardware device. If QoS settings have already been checked and there are still VoIP quality issues, there are a few other culprits that are likely to interfere with service delivery.

Changing codecs. The next item on the list is to check whether codecs are changing. When calls are established, phone systems communicate which codecs are supported. Typically, phones will use the highest-quality codec when the call starts. But if something happens during the call, and the phone senses high jitter or data loss, the codecs will get changed. By looking at which codecs were used inside a Real-Time Transport Protocol stream, you can actually see, for example, that a call may have started off at the G.711 codec, which is 64 Kbps sampling, then changed to G.729, which is only 8 Kbps sampling. This makes for a less choppy-sounding audio, but causes a drastic drop in quality. Typically, codec changes happen due to network congestion.

High network utilization and network congestion. Another way to reduce the time it takes to troubleshoot VoIP issues is to establish accurate baselines. In larger enterprise environments, this can mean several network probes collecting data. In other words, what is “normal” on the network? What is the normal utilization? What are the normal protocols that are running? Baselines let you know when things get out of whack, because network utilization can affect VoIP quality.

While monitoring packets, it is important you pay close attention to network use. Tracking timestamps during instances of high jitter or packet loss and comparing this data to the intervals of higher network traffic can provide valuable insights.

One enterprise VoIP user, the global finance company Santander, reported solving a VoIP quality issue in this way: An Adobe update to Acrobat caused significant problems to the company’s network — calls suddenly began to drop off across its call centers. By looking at the high spike in traffic compared to when calls started dropping, network administrators were able to identify high utilization as the cause of the problem. They then evaluated post-event capture data and discovered a surge of Internet traffic flowing to Adobe IP addresses. The fix, as it turned out, was rather simple: Santander IT set up Adobe Reader to access local servers for updates instead of going out to the Internet. Problem solved.

By following these steps to avoid VoIP quality killers, troubleshooting time can be reduced and service delivery improved. A retrospective network analyzer can also help engineers spot future trends and allow them to resolve issues before they become problems.

Thanks to Tech Target for the article.

Unified Communications VoIP

Network Configuration Management is a Key Component in Business Today

Network configuration management is the process of organizing and maintaining information about all the components of a computer network.

When a network needs repair, alteration, development or advancements, the administrator refers to the network configuration management database to determine the best course of action.

This database contains the locations and network addresses of all hardware devices, as well as information about the programs, versions and updates installed in network computers.

There are many advantages you have while implementing configuration management such as:

Minimizing configuration errors.
Minimizing downtime.
Optimizing network security.
Improving the processes of maintenance, repair, and expansion and upgrading.

Companies such as Cisco have been developing network configuration applications for years now and they feel it is a necessity and not an option in business today.

By using it, it allows you to roll out configuration changes to numerous network devices within minutes rather than hours, or even days. Push out a config change in real time or schedule it for after hours.

It makes you take advantage of the central repository for all network devices by automatically backing up your configurations. This automated approach allows you to sleep at night knowing that you can always have the most up to date configurations of your devices.

The web interface quickly gives you a user friendly snapshot of the status of your devices providing you the knowledge of what devices are backed up, not backed up, have start/run conflicts, etc.

One of the main leaders in the tech industry Infosim has come out with statement saying that

“Through 2015, 80% of outages impacting mission-critical services will be caused by people and process issues, and more than 40% of those outages will be caused by change, configuration, release integration and hand-off issues.”

This can all be easily avoided by using one of our configuration applications. To find out more get in contact with the team.

Thanks to NMSaaS for the article.

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