CAC Utilization Statistics via SNMP

The Oracle Communications Session Border Controller allows you to retrieve information on current session utilization and burst rate as a percentage of their configured maximums on per session-agent and/or realm basis. The Oracle Communications Session Border Controller uses the configured max-session and max-burst-rate settings in conjunction with a percentage formula to calculate this value. The system also uses an ACLI configuration setting to establish the threshold at which trap and trap clear messages are sent from the SNMP agent to the configured manager(s).

The user must load the MIB version associated with this software version on all pertinent SNMP managers to query these CAC utilization (occupancy) values and interpret the traps. In addition, the user must configure the threshold at which the system generates the CAC utilization trap. Note that the corresponding clear trap uses the same threshold setting, sending the clear trap when utilization falls below 90% of the threshold.

SNMP Get for CAC Utilization

Using a MIB browser, the user can query the current percentage utilization values for both max-session and max-burst-rate for any session-agent or realm. The calculations for these utilization levels are:

Session utilization level = (current session count * 100 ) / max-sessions
Burst rate utilization level = (current burst rate * 100 ) / max-burst-rate

The MIB objects associated with these statistics are parallel for session agent and realm and include a table to contain the objects, an object associating the objects containing the values with the applicable table, and objects containing the values themselves. These objects are listed below.

The MIB objects containing CAC utilization data for Session Agents are listed below.

The object establishing the statistics table for session agent CAC utilization follows:

--apSip Session Agent Connection Admission Control Stats Table
apSipSaCacStatsTable OBJECT-TYPE
        SYNTAX          SEQUENCE OF ApSipSaCacStatsEntry
        MAX-ACCESS      not-accessible
        STATUS          current
        DESCRIPTION
            "SIP Session Agent Connection Admission Control Stats Table."
        ::= { apSipMIBTabularObjects 5 }

The object establishing the session agent CAC utilization statistics objects follows:

apSipSaCacStatsEntry OBJECT-TYPE
        SYNTAX          ApSipSaCacStatsEntry
        MAX-ACCESS      not-accessible
        STATUS          current
        DESCRIPTION
            "Connection Admission Control Statistics."
        AUGMENTS { apSipSessionAgentStatsEntry }
     ::= { apSipSaCacStatsTable 1 }

The session agent CAC utilization statistics values include:

ApSipSaCacStatsEntry ::= SEQUENCE {
    apSipSaCacSessionUtilLevel                 Gauge32,
    apSipSaCacBurstRateUtilLevel               Gauge32
}

The above objects, specifying the CAC utilization value for sessions and burst rate utilization for session agents include:

apSipSaCacSessionUtilLevel        OBJECT-TYPE
    SYNTAX        Gauge32
    UNITS        "percentage"
    MAX-ACCESS     read-only
    STATUS        current
    DESCRIPTION
        "Current session utilization level."
    ::= { apSipSaCacStatsEntry 1 }


apSipSaCacBurstRateUtilLevel        OBJECT-TYPE
    SYNTAX        Gauge32
    UNITS        "percentage"
    MAX-ACCESS     read-only
    STATUS        current
    DESCRIPTION
        "Current burst rate utilization level."
    ::= { apSipSaCacStatsEntry 2 }

The MIB objects containing CAC utilization data for Realms are listed below.

The object establishing the statistics table for realm CAC utilization follows:

--apSig Realm Connection Admission Control Stats Table
apSigRealmCacStatsTable OBJECT-TYPE
        SYNTAX          SEQUENCE OF ApSigRealmCacStatsEntry
        MAX-ACCESS      not-accessible
        STATUS          current
        DESCRIPTION
            "Realm Connection Admission Control Stats Table."
        ::= { apSipMIBTabularObjects 6 }

The object establishing the realm CAC utilization statistics objects follows:

apSigRealmCacStatsEntry OBJECT-TYPE
        SYNTAX          ApSigRealmCacStatsEntry
        MAX-ACCESS      not-accessible
        STATUS          current
        DESCRIPTION
            "Connection Admission Control Statistics."
        AUGMENTS { apSigRealmStatsEntry }
     ::= { apSigRealmCacStatsTable 1 }

The session agent CAC utilization statistics values include:

ApSigRealmCacStatsEntry ::= SEQUENCE {
    apSigRealmCacSessionUtilLevel              Gauge32,
    apSigRealmCacBurstRateUtilLevel            Gauge32
}

The above objects, specifying the CAC utilization value for sessions and burst rate utilization for realms include:

apSigRealmCacSessionUtilLevel        OBJECT-TYPE
    SYNTAX        Gauge32
    UNITS        "percentage"
    MAX-ACCESS     read-only
    STATUS        current
    DESCRIPTION
        "Current session utilization level."
    ::= { apSigRealmCacStatsEntry 1 }

apSigRealmCacBurstRateUtilLevel        OBJECT-TYPE
    SYNTAX        Gauge32
    UNITS        "percentage"
    MAX-ACCESS     read-only
    STATUS        current
    DESCRIPTION
        "Current burst rate utilization level."
    ::= { apSigRealmCacStatsEntry 2 }

CAC Utilization Traps

The Oracle Communications Session Border Controller can issue a trap when either the value of max-session or CAC burst rate exceeds a configured value. The system only sends one trap when the threshold is exceeded. When the value falls back under 90% of this threshold, the Oracle Communications Session Border Controller sends a clear trap.

You configure the value that triggers these traps as a percentage of the max-session and max-burst-rate settings configured for the applicable session agent and/or realm. The system uses the same setting to specify when to send both the sessions and burst rate traps. The name of this parameter is the cac-trap-threshold.

For realms, you configure a session-constraint element with the cac-trap-threshold setting and apply that session constraint to the realm. For a session agent however, you configure the cac-trap-threshold directly within the session agent's configuration.

The syntax for the command is the same within session constraint and session agent configurations.

cac-trap-threshold[0-99]

You must express the value as a number less than 100. There is no default setting; the system does not generate a trap if you have not configured this setting.

The apSipCACUtilAlertTrap identifies the threshold exceeded on a per-element and per-value (session count or burst rate) for each trap, including:

apSipSaCacSessionUtilLevel
apSipSaCacBurstRateUtilLevel
apSipRealmCacSessionUtilLevel
apSipRealmCacBurstRateUtilLevel