Before you design your first assessment of VoIP Quality, research your network and your proposed VoIP implementation. First, look at existing network documentation to find peak and average usage statistics. For instance, telephone records are a good source of data about the likely call volume your network will have to handle. Then check the vendor data sheets to answer the following questions:
What type of codec will you be using?
Will this codec use silence suppression or packet loss concealment?
How many simultaneous calls need to be supported?
Can your network currently support QoS for VoIP?
What size jitter buffer will be used?
You should emulate these factors as closely as possible when you design VoIP Quality assessments.
To configure and run a VoIP Quality assessment, take the following steps:
|
Step |
Description |
|---|---|
|
Step 1 |
Discover the endpoints installed in your network. You specify a range of IP addresses to scan. Endpoints that are discovered are added to the database and available in the Design view. For more information, see Section 7.3, Discovering. |
|
Step 2 |
Design the assessment schematically in the Design view. Choose the computers where the simulated voice over IP traffic will run and connect them using VoIP connectors. For more information, see Section 7.4, Designing a VoIP Quality Assessment. Create endpoints to represent the different areas of your network. Create at least one call group that spans a WAN link, assuming your deployment will include one. When creating connectors, create only one connector for each call script (representing a codec type) you want to include in the assessment. To add more calls, change the “Connector Multiplier” in the Create a Connector dialog box. The multiplier corresponds to the number of simulated calls that will be sent simultaneously over the connection between the endpoints in the call group. If your network contains a firewall, you need to do some extra configuration, both in Vivinet Assessor and at the firewall itself. For more information, see Section 7.8.2, Working with Firewalls. |
|
Step 3 |
Schedule the assessment in the Schedule view. The scheduling parameters for a VoIP Quality assessment allow you to run a quick call-quality check by sending a single set of simulated calls over the network and measuring the resulting MOS, or to send and measure calls periodically over the course of up to a week. A typical assessment runs for about seven days, enough to get plenty of data from different days of the week when network traffic conditions are different. However, for your first assessment, run for a few hours and then scan your results. You can then reset the schedule for a longer time period if the assessment is providing meaningful results and including enough representative endpoints The schedule interval determines how heavy the simulated VoIP traffic will appear to your network equipment. To simulate heavier traffic (more frequent calls), choose a smaller interval. You should already have some idea of what peak and average utilization on your network will be; if not, do some traffic analysis to find out. For more information, see Section 7.5, Scheduling a VoIP Quality Assessment. |
|
Step 4 |
Verify that the computers you selected can be reached, and that they have Performance Endpoint software installed. Verification runs a mini-assessment to determine whether your assessment is ready to run successfully as completed. Experiment with different configurations at this stage and correct the causes of any errors you see before you run the assessment. For more information, see Section 7.6, Verifying a VoIP Quality Assessment. |
|
Step 5 |
Run the assessment. While the assessment is running, your presence is no longer required. However, you should plan to check the assessment periodically to make sure no major errors have occurred that might interfere with results. For more information, see Section 7.7, Running a VoIP Quality Assessment. |
|
Step 6 |
Generate reports. Reports contain much more useful information if you have followed the advice offered above. They are also more useful if you assign helpful endpoint names to the endpoints You will notice that by default, the reports label the results according to the call group names, which are combinations of the ’ names. Another option is to assign a Connector Comment to each connector to achieve the same purpose—identifying the call groups in reports and in charts. Names that describe the locations of the endpoints are perhaps the most helpful. For more information, see Section 8.0, Generating Reports. |