application-model multimedia

Sets the characteristics that affect the behavior of the multimedia application model, which optimizes real-time applications on your network. Examples include voice over IP, streaming audio, and video conferencing applications.

application-model multimedia
 
             { ( clip { half-life <hlife> |
 
                      metric-contribution <mcontr> |
 
                      threshold <threshold>
 
                      }
 
               ) |
 
               ( delay { half-life <hlife> |
 
                      metric-contribution <mcontr> |
 
                      }
 
               ) |
 
               ( jitter min-buffer <mbuff> ) |
 
               ( loss { descent-rate <meas> <target-loss> } |
 
                        half-life <hlife> |
 
                        metric-contribution <mcontr>
 
                      }
 
               )
 
               ( metric half-life <hlife> )
 
             }
 
no application-model multimedia
 
no application-model multimedia clip [ half-life | metric-contribution 
 
                                       threshold ]
 
no application-model multimedia delay [ half-life | metric-contribution ]
 
no application-model multimedia jitter [ min-buff ]
 
no application-model multimedia loss [ descent-rate | half-life | 
                                       metric-contribution ]
 
no application-model multimedia metric [ half-life ]
 

 

• hlife--(exact meaning depends upon which of the following keywords is used)
• clip half-life: exponential decay of the effects of a clip; range: 0 through 15000 (default 20)
• delay half-life: smoothing factor of average delay; range: 0 through 15000 (default 150)
• loss half-life: smoothing factor of measured loss; range: 0 through 15000 (default 150)
• metric half-life: internal parameter - do not change; range: 0 through 150000 (default 1500)
• mcontr--(exact meaning depends upon which of the following keywords is used)
• clip metric-contribution: range: 0 through 1000 (default is 500)
• delay metric-contribution: range: 0 through 1000 (default is 800)
• loss metric-contribution: internal parameter - do not change; range: 0 through 1000 (default is 10)
• threshold--the number of consecutively lost packets that would be considered a clip event; range: 0 through 100 (default 2)
• mbuff--amount of buffer delay introduced by a client; range: 0 through 1000 (default 80)
• meas--internal parameter - do not change; range: 0 through 5000 (default 250)
• target-loss--internal parameter - do not change; range: 1 through 100 (default 1)

Must be in engine or policy configuration mode (config-engine or config-engine-policy), which requires privileged-level access.

Available for use multiple times in the configuration.

Use the application-model multimedia command to change the default behavior of this model to suit the particular needs of your network. You may create as many variants as you wish by assigning each to a specific decision policy. See Details on Application Models in Chapter 6: Decision Policies and Application Models of the CNA Basic Monitoring Guide.

NOTE: When using the multimedia application model, you must use either the traceprobe or ICMP measurement modes. If you are able to employ only TCP, then you should use the web or other application model.

The following keywords control the major components of the multimedia application model:

• clip - defines the impact and severity of the loss of consecutive packets. half-life sets the exponential decay of the effects of a clip on the decision-maker’s calculations. A high number will cause decisions to be influenced by a clip event for a longer period. A low number will limit the effects of clip events to a shorter period, which can cause transitions to be less smooth (e.g., the decision-maker may change certain decisions more frequently). metric-contribution affects the weighting of a clip event’s effect on the decision-maker’s calculations. A higher value for this parameter will cause the decision-maker to treat a clip event more significantly. The threshold parameter sets the number of consecutively lost packets that determine a clip event.
• delay - determines how the moving average of delay is calculated. The half-life parameter controls the smoothness of the moving average: A high value results in smaller changes in the calculated average delay because the delay contribution of past measurements will be greater than when half-life is set low.
• jitter min-buffer - sets the amount of buffer delay introduced by a client application (e.g., voice over IP, video conferencing), in milliseconds
• loss descent-rate - this is an internal parameter, do not change it
• loss half-life - controls the smoothing factor of measured loss. A high value results in a smaller contribution of past loss events; conversely, a low value will allow past loss events to have a greater influence on the decision-maker’s calculations.
• metric - this is an internal parameter, do not change it

Use the no form of the command to revert to the default settings.