Configuring Quality of Service Rules

The Quality of Service Rules table lets you configure up to 510 Quality of Service rules. A Quality of Service rule defines an action to perform when the threshold (major or minor) of a specific performance monitoring call metric is crossed for a specific IP Group. The call metric can be voice quality (i.e., MOS), bandwidth, Answer-seizure ratio (ASR), Network Effectiveness Ratio (NER), or Average Call Duration (ACD).

Depending on the call metric, you can configure the following actions to be performed if the threshold is crossed:

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Reject calls to the IP Group for a user-defined duration. Rejection of calls can also trigger alternative routing. When the device rejects a call due to an ASR, NER or ACD threshold crossing, it generates the SIP response code 850 (Signaling Limits Exceeded). When the device rejects a call due to Voice Quality and Bandwidth threshold crossing, it generates the SIP response code 806 (Media Limits Exceeded). If you configure these SIP response codes for an Alternative Reasons Set (see Configuring SIP Response Codes for Alternative Routing Reasons) that is assigned to the IP Group ('SBC Alternative Routing Reasons Set' parameter) and the device rejects a call, it searches in the IP-to-IP Routing table for an alternative routing rule.

When the device rejects calls to an IP Group based on a Quality of Service rule, it raises an SNMP alarm (acIpGroupNoRouteAlarm). The alarm is also raised upon a keep-alive failure with the IP Group. For more information, refer to the document SBC-Gateway Series SNMP Alarm Reference Guide.

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Use a different IP Profile for the IP Group or current call. This action can be useful, for example, when poor quality occurs due to packet loss and the device can then switch to an IP Profile configured with a higher RTP redundancy level or lower bit-rate coder.

To learn more about which actions are supported per call metric, see the description of the 'Rule Action' parameter below.

To configure thresholds, see the following sections:

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Voice Quality (MOS) - Configuring Quality of Experience Profiles

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Bandwidth - Configuring Bandwidth Profiles

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ASR, ACD and NER - See Alarm Thresholds

The following procedure describes how to configure Quality of Service rules through the Web interface. You can also configure it through ini file [QualityOfServiceRules] or CLI (configure voip > qoe quality-of-service-rules).

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To configure a Quality of Service rule:

1.

Open the Quality of Service Rules table (Setup menu > Signaling & Media tab > Media folder > Quality of Service Rules).

2.

Click New; the following dialog box appears:

3.

Configure a rule according to the parameters described in the table below.

4.

Click Apply, and then restart the device with a save-to-flash for your settings to take effect.

Quality of Service Rules Table Parameter Descriptions

Parameter	Description
Match
'Index' [Index]	Defines an index number for the new table row. Note: Each row must be configured with a unique index.
'IP Group' ip-group-name [IPGroupName]	Assigns an IP Group. The rule applies to all calls belonging to the IP Group. Note: This parameter is mandatory.
'Rule Metric' rule-metric [RuleMetric]	Defines the performance monitoring call metric to which the rule applies if the metric's threshold is crossed. ■ [0] Voice Quality = (Default) The device calculates MOS of calls and if the threshold is crossed (i.e., poor quality), the configured action (see 'Rule Action' parameter below) is done for all new calls and for the entire IP Group. ■ [1] Bandwidth ■ [2] ACD ■ [3] ASR ■ [4] NER ■ [5] Poor InVoice Quality = The device calculates MOS (and TMMBR) of the call and if the threshold is crossed (i.e., poor quality), the device uses a different IP Profile (see 'Rule Action' parameter below) for the current call only (not the entire IP Group). This option is also used for voice quality for unregistered users (see Configuring Voice Quality for Unregistered Users). ■ [6] Registered User Voice Quality = The device calculates the MOS of calls belonging to users that are registered with the device. For more information on this feature, see Configuring Voice Quality for Registered Users. Note: ✔ When this option is selected, a User-type IP Group must be selected in the 'IP Group' parameter (above). ✔ This option is applicable only to the SBC application.
'Severity' severity [Severity]	Defines the alarm severity level. When the configured severity occurs, the device performs the action of the rule. ■ [0] Major (Default) ■ [1] Minor Note: If you configure the 'Rule Metric' parameter to ACD, ASR or NER, you must configure the parameter to Major. For all other 'Rule Metric' parameter values, you can configure the parameter to any value.
Action
'Rule Action' rule-action [RuleAction]	Defines the action to be done if the rule is matched. ■ [0] Reject Calls = (Default) New calls destined to the specified IP Group are rejected for a user-defined duration. To configure the duration, use the 'Calls Reject Duration' parameter (see below). ■ [1] Alternative IP Profile = A different IP Profile is used for the IP Group or call (depending on the 'Rule Metric' parameter). To specify the IP Profile, use the 'Alternative IP Profile Name' parameter (see below). Note: ■ If you configure the 'Rule Metric' parameter to ACD, ASR or NER, you must configure the parameter to Reject Calls. ■ If you configure the 'Rule Metric' parameter to Voice Quality or Bandwidth: ✔ If you configure the 'Severity' parameter to Minor, you must configure the parameter to Alternative IP Profile. ✔ If you configure the 'Severity' parameter to Major, you can configure the parameter to any option. When configured to Alternative IP Profile and the threshold is crossed, the device changes the IP Profile for the entire IP Group for all new calls. ■ If you configure the 'Rule Metric' parameter to Poor InVoice Quality, you must configure the parameter to Alternative IP Profile. If the threshold is crossed (i.e., poor call quality), the device changes the IP Profile for the specific call only (during the call). ■ If you configure the 'Rule Metric' parameter to Registered User Voice Quality: ✔ If you configure the 'Severity' parameter to Minor, you must configure the parameter to Alternative IP Profile. If the threshold is crossed (i.e., poor MOS), the device changes the IP Profile (from the original IP Profile configured with the G.711 coder to the alternative IP Profile configured with the Opus coder)during the call. As soon as the device detects an improvement in the network (based on packet loss), it returns to the original IP Profile. ✔ If you configure the 'Severity' parameter to Major, you can configure the parameter to any option. ✔ If you configure the parameter to Alternative IP Profile, new calls will initially use the coder that was last used in the previous call (regardless of MOS). ✔ If you configure the parameter to Alternative IP Profile, this feature is not supported for HA switchover (e.g., if coder changed to Opus before switchover, after switchover the call remains with Opus until it ends, regardless of MOS level). ✔ If you configure the parameter to Alternative IP Profile and the device supports other media types (e.g., video) in addition to audio, at least one of the peers must support re-INVITE without SDP.
'Calls Reject Duration' calls-reject-duration [CallsRejectDuration]	Defines the duration (in minutes) for which the device rejects calls to the IP Group if the rule is matched. The default is 5. Note: The parameter is applicable only if the 'Rule Action' parameter is configured to Reject Calls.
'Alternative IP Profile Name' alt-ip-profile-name [AltIPProfileName]	Assigns a different IP Profile to the IP Group or call (depending on the 'Rule Metric' parameter) if the rule is matched. By default, no value is defined. Note: The parameter is applicable only if the 'Rule Action' parameter is configured to Alternative IP Profile.