7.4 Using QoS Alarms

The following steps are an overview of how to use QoS alarms in your application. For details, refer to the specific API and data structure descriptions:

1. Call ipm_GetQoSThreshold( ) to retrieve the current settings of QoS parameters.
2. Set up the IPM_QOS_THRESHOLD_INFO structure with desired values for QoS parameter settings.
3. Call ipm_SetQoSThreshold( ) to set the desired QoS parameters. This function may be called at any time by an application, including while a session is in progress.
4. Call ipm_EnableEvents( ) to start QoS parameter monitoring.
5. When a QoS alarm has been triggered, an IPMEV_QOS_ALARM event is sent by the system.
6. Use standard runtime library API functions to query the IPMEV_QOS_ALARM_DATA structure to retrieve more details about the alarms which have been triggered.
7. Call ipm_DisableEvents( ) to stop QoS parameter monitoring.

The following pseudocode illustrates how you might use QoS alarms in an application.

#include <stdio.h>
#include <srllib.h>
#include <ipmlib.h>
typedef long int(*HDLR)(unsigned long);
void CheckEvent(); 
/* % Packet Loss */
Time_Interval = 1000;           /* 1 second                           */
Debounce_On = 20000;            /* 20 seconds                         */
Debounce_Off = 45000;           /* 45 seconds                         */
Fault_Threshold = 6;            /* 2 lost 30 msec packets per second. */
Percent_Success_Threshold = 10; /* 10 seconds (in 20 seconds)         */
Percent_Fail_Threshold = 30;    /* 30 seconds (in 45 seconds)         */ 
/* Jitter */
Time_Interval = 100;             /* 100 msec                          */
Debounce_On = 20000;             /* 20 seconds                        */
Debounce_Off = 45000;            /* 45 seconds                        */
Fault_Threshold = 360;           /* 1.5 30 msec G711 packet jitter per second. (unscaled) */
Percent_Success_Threshold = 100; /* 10 seconds (in 20 seconds)        */
Percent_Fail_Threshold = 300;    /* 30 seconds (in 45 seconds)        */ 
void main()
{
    int nDeviceHandle;
    eIPM_EVENT myEvents[3] ={EVT_ROUNDTRIPLATENCY, EVT_LOSTPACKETS, EVT_JITTER};
    // Register event handler function with srl
    sr_enbhdlr( EV_ANYDEV ,EV_ANYEVT ,(HDLR)CheckEvent);
    /*
    .
    Main Processing
    .
    */ 
    /*
    Need to enable three events for IP device handle, nDeviceHandle.
    ASSUMPTION: A valid nDeviceHandle was obtained from prior call to ipm_Open().
    */
    if(ipm_EnableEvents(nDeviceHandle, myEvents, 3, EV_SYNC) == -1)
    {
        printf("ipm_EnableEvents failed for device name %s with error = %d\n",
            ATDV_NAMEP(nDeviceHandle), ATDV_LASTERR(nDeviceHandle));
            /*
            .
            Perform Error Processing
            .
            */
    }
    /*
    .
    Continue Processing
    .
    */
} 
void CheckEvent()
{
    int nEventType = sr_getevttype();
    int nDeviceID = sr_getevtdev();
    switch(nEventType)
    {
    /*
    .
    . List of expected events
    .
    */
        /* When alarm occurs you get this event. */ 
    case IPMEV_QOS_ALARM:
        {
            printf("Received IPMEV_QOS_ALARM for device = %s\n",
                ATDV_NAMEP(nDeviceID));
            IPM_QOS_ALARM_DATA * l_pAlarm = (IPM_QOS_ALARM_DATA*)l_pVoid;
            switch(l_pAlarm->eQoSType)
            {
            case QOSTYPE_ROUNDTRIPLATENCY:
                printf("QOSTYPE_ROUNDTRIPLATENCY=%d\n", l_pAlarm->eAlarmState);
                break;
            case QOSTYPE_JITTER:
                printf("QOSTYPE_JITTER=%d\n", l_pAlarm->eAlarmState);
                break;
            case QOSTYPE_LOSTPACKETS:
                printf("QOSTYPE_LOSTPACKETS=%d\n", l_pAlarm->eAlarmState);
                break;
            }
            break;
        } 
    default:
        printf("Received unknown event = %d for device = %s\n",
            nEventType, ATDV_NAMEP(nDeviceID));
        break; 
    }
}
 

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