When you create a modeled link, you select modeling parameters that determine what VoIP network scenario you want to investigate. You can base your selections on the information obtained from the Utilization Assessment task.
After Utilization monitoring is complete, the Model Bandwidth view contains a table of all discovered links. For more information, see Section 6.1, Understanding Bandwidth Modeling.
NOTE:You cannot perform link modeling while Utilization monitoring is active. Wait until Utilization monitoring is complete.
To model a discovered link:
Click the Model Bandwidth view tab.
In the Monitored Links table, highlight the link you want to model.
Click Create Modeled Link.
Complete the fields in the dialog box as follows:
Field |
Description |
---|---|
Link name |
The name of the WAN or LAN link to be modeled. Can be a link that Vivinet Assessor discovered while performing inventory on your network, or a link that you entered manually. Corresponds to the link you highlighted in the Monitored Links table. Or, if you are creating a generic link to model, enter the link name. |
Link type |
The type of link to be modeled, such as serial, ATM, or frame-relay. Corresponds to the link you highlighted in the Monitored Links table. Or, if you are creating a generic link to model, select the link type from the list. |
Call script |
Corresponds to one of the supported VoIP codecs, such as G.729. For more information, see Section 7.10, Working with Call Scripts. |
Compress RTP headers |
Refers to a bandwidth-conversion technique: RTP header compression (cRTP). Compression can reduce the size of the RTP header, which otherwise takes 40 bytes. For more information, see Section 6.1.3, RTP Header Compression. |
Number of calls to model |
Can be specified in Erlangs or in number of calls. If you specify Erlangs, then the corresponding number of calls appears. If you specify Erlangs you also must specify the blocking percentage, which is the percentage of calls that are blocked because not enough lines are available. An Erlang is a unit of traffic density in a telecommunications system. One Erlang is the equivalent of one call (including call attempts and hold time) in a specific channel for 3600 seconds, which need not occur in a continuous block. An Erlang value of "1" means that the telephone line is 100% busy. For more information, see Section 6.1, Understanding Bandwidth Modeling. |
Link speed |
The absolute throughput capacity of this link, as determined during discovery scanning. Can be expressed in kbps. |
Target utilization |
Ideal target for bandwidth utilization. Expressed as a percentage of link capacity. For more information, see Section 6.1.2, Call Volumes. |
Click OK. The results of the modeling are displayed in the Modeled Links table.
For more information, see Section 6.3, Understanding Results from Bandwidth Modeling.
In addition to modeling discovered links, you can run a limited set of bandwidth calculations on a link that Vivinet Assessor has not discovered and monitored. Simply click Create Generic Modeled Link and select the modeling parameters as described in To model a discovered link:. Bandwidth utilization information is not available for models that are not based on discovered links.
To change any model parameters and re-run the modeling scenario, highlight a link in the Modeled Links table and click Edit.
To remove a link, highlight a link in the Modeled Links table and click Delete.