Policy Table Case Study

The following case study is derived and simplified from actual carrier policies and illustrates how a large set of policies can be consolidated using a policy table.

A wireless carrier named Example Inc. offers three monthly data usage plans for its subscribers. The monthly quota levels are 100 MB, 2 GB, and 150 GB. Seven policies are used to capture the business logic for each usage plan, as follows:

When subscribers near their monthly quota limit, the carrier sends an SMS notification.
When subscribers reach their monthly quota limit, the carrier sends an SMS notification, sets an additional quota (at an additional price), sets a new warning threshold, and sets a new limit threshold.
When subscribers reach the additional limit, the carrier sends an SMS notification and throttles additional usage to 64 kbps.

The rules for each usage plan are collected in a policy group: to support the three plans, there are three policy groups. Finally, triggering policies determine which policy group to execute based on the entitlement of the subscriber.

The names the carrier uses for the groups, and the names of the policies each contains, are as follows. The groups are named for the data plans (100_MB, 2_GB, and 100_GB), and the policies are named for the data plans and the actions each policy performs.

Quotas and Policy Names
Group Name	Policy Name
Quota_100_MB	Quota_100_MB_send_70_percent_SMS
	Quota_100_MB_send_100_percent_SMS
	Quota_100_MB_additional_quota_send_100_percent_SMS
	Quota_100_MB_set_70_percent_volume_threshold
	Quota_100_MB_set_100_percent_volume_threshold
	Quota_100_MB_additional_quota_set_100_percent_volume_threshold
	Throttle_64_kbps_100_MB
Quota_2_GB	Quota_2_GB_send_90_percent_SMS
	Quota_2_GB_send_100_percent_SMS
	Quota_2_GB_additional_quota_send_100_percent_SMS
	Quota_2_GB_set_90_percent_volume_threshold
	Quota_2_GB_set_100_percent_volume_threshold
	Quota_2_GB_additional_quota_set_100_percent_volume_threshold
	Throttle_64_kbps_2_GB
Quota_100_GB	Quota_100_GB_send_90_percent_SMS
	Quota_100_GB_send_100_percent_SMS
	Quota_100_GB_additional_quota_send_100_percent_SMS
	Quota_100_GB_set_90_percent_volume_threshold
	Quota_100_GB_set_100_percent_volume_threshold
	Quota_100_GB_additional_quota_set_100_percent_volume_threshold
	Throttle_64_kbps_100_GB

Comparing the triggering policies shows that they differ only in the name of the entitlement to match and the policy group to execute:

Trigger Policy: Evaluate 3G Volume Quota Group Quota_100_MB

where the ENTITLEMENTS is contained in Match Lists Ent_100MB_Quota

evaluate policy group Quota_100_MB

Trigger Policy: Evaluate 3G Volume Quota Group Quota_2_GB

where the ENTITLEMENTS is contained in Match Lists Ent_2GB_Quota

evaluate policy group Quota_2_GB

Trigger Policy: Evaluate 3G Volume Quota Group Quota_100_GB

where the ENTITLEMENTS is contained in Match Lists Ent_100GB_Quota

evaluate policy group Quota_100_GB

Similarly, comparing the corresponding policies in different groups shows that they are mostly the same, with only a few isolated differences:

Group: Quota 100MB; Policy: Quota 100MB send 70 percent SMS

where the user is using greater than or equal to 70 percent and less than 100 percent of volume for DP_QUOTA.100MB quota
And where the event trigger is one of USAGE_THRESHOLD_REACHED
send SMS `You have consumed 70 % of your total quota allotted on Example Inc.` to user. Request delivery receipt `default`.
send notification to syslog with `SMS 70%;{User.E164};{User.Custom5};{User.Custom6};GOLD;{User.Entitlement};You have consumed 70 % of your total quota allotted on Example Inc.` and severity `Info`
Advanced: set values for QoS and Charging parameters to 
Diameter IP-CAN Session Usage Monitoring  USAGE_MONITORING_ENABLED

continue processing message

Group: Quota 2GB; Policy: Quota 2GB send 90 percent SMS

where the user is using greater than or equal to 90 percent and less than 100 percent of volume for DP_QUOTA.2GB quota
And where the event trigger is one of USAGE_THRESHOLD_REACHED
send SMS `You have consumed 90 % of your total quota allotted on Example Inc.` to user. Request delivery receipt `default`.
send notification to syslog with `SMS 90%;{User.E164};{User.Custom5};{User.Custom6};GOLD;{User.Entitlement};You have consumed 90 % of your total quota allotted on Example Inc.` and severity `Info`
Advanced: set values for QoS and Charging parameters to 
Diameter IP-CAN Session Usage Monitoring  USAGE_MONITORING_ENABLED

continue processing message

Group: Quota 100GB; Policy: Quota 100GB send 90 percent SMS

where the user is using greater than or equal to 90 percent and less than 100 percent of volume for DP_QUOTA.100GB quota
And where the event trigger is one of USAGE_THRESHOLD_REACHED
send SMS `You have consumed 90 % of your total quota allotted on Example Inc.` to user. Request delivery receipt `default`.
send notification to syslog with `SMS 90%;{User.E164};{User.Custom5};{User.Custom6};GOLD;{User.Entitlement};You have consumed 90 % of your total quota allotted on Example Inc.` and severity `Info`
Advanced: set values for QoS and Charging parameters to 
Diameter IP-CAN Session Usage Monitoring  USAGE_MONITORING_ENABLED

continue processing message

Group: Quota 100MB; Policy: Quota 100MB additional quota set 100 percent volume threshold

where the user is using greater than or equal to 100 percent of total volume for DP_QUOTA.100MB quota
And where the user is using less than 100 percent of total volume for DP_QUOTA_ADDL.3GB quota
remove PCC rule types all for all
install 16Mbps_DL_5.76Mbps_UL PCC rules for flow
grant total volume to 100 percent used for DP_QUOTA_ADDL.3GB
Advanced: set values for QoS and Charging parameters to 
Diameter Enforcement Session Event Triggers  REVALIDATION_TIMEOUT, USAGE_THRESHOLD_REACHED
Diameter IP-CAN Session Usage Monitoring  USAGE_MONITORING_ENABLED

accept message

Group: Quota 2GB; Policy: Quota 2GB additional quota set 100 percent volume threshold

where the user is using greater than or equal to 100 percent of total volume for DP_QUOTA.2GB quota
And where the user is using less than 100 percent of total volume for DP_QUOTA_ADDL.4GB quota
remove PCC rule types all for all
install 16Mbps_DL_5.76Mbps_UL PCC rules for flow
grant total volume to 100 percent used for DP_QUOTA_ADDL.4GB
Advanced: set values for QoS and Charging parameters to 
Diameter Enforcement Session Event Triggers  REVALIDATION_TIMEOUT, USAGE_THRESHOLD_REACHED
Diameter IP-CAN Session Usage Monitoring  USAGE_MONITORING_ENABLED

accept message

Group: Quota 100GB; Policy: Quota 100GB additional quota set 100 percent volume threshold

where the user is using greater than or equal to 100 percent of total volume for DP_QUOTA.100GB quota
And where the user is using less than 100 percent of total volume for DP_QUOTA_ADDL.5GB quota
remove PCC rule types all for all
install 16Mbps_DL_5.76Mbps_UL PCC rules for flow
grant total volume to 100 percent used for DP_QUOTA_ADDL.5GB
Advanced: set values for QoS and Charging parameters to 
Diameter Enforcement Session Event Triggers  REVALIDATION_TIMEOUT, USAGE_THRESHOLD_REACHED
Diameter IP-CAN Session Usage Monitoring  USAGE_MONITORING_ENABLED

accept message

All the differences in the seven policies for the three groups can be tabulated using only six columns and three rows, as follows. Because of the similarities from group to group, these policies are good candidates for using a policy table. These three groups can be replaced by one set of policies using variables for differences and one policy table with three rows. The table's key column, representing the scenarios, is a policy context property. The table column headings become the names of the other variables used in the policies.

Differences Between Quotas
Policy Variable Scenario	Base Quota	Additional Quota	Percent Limit	Additional Limit	Grant Quota
100 MB	DP_QUOTA.100MB	DP_QUOTA_ADDL.3GB	70	3 GB	DP_QUOTA_ADDL.3GB
2 GB	DP_QUOTA.2GB	DP_QUOTA_ADDL.4GB	90	4 GB	DP_QUOTA_ADDL.4GB
100 GB	DP_QUOTA.100GB	DP_QUOTA_ADDL.5GB	90	5 GB	DP_QUOTA_ADDL.5GB

The triggering policies are now rewritten to use the policy table and a single policy group, which in this case study is named QUOTA. A policy context property is used as the key to locate the row in the table to use.

Table-Driven Trigger Policy: Evaluate 3G Volume Quota Group 100 MB

where the ENTITLEMENTS is contained in Match Lists Ent_100MB_Quota
set policy context property scenario to 100MB
evaluate policy group QUOTA

Table-Driven Trigger Policy: Evaluate 3G Volume Quota Group 2 GB

where the ENTITLEMENTS is contained in Match Lists Ent_2GB_Quota
set policy context property scenario to 2GB
evaluate policy group QUOTA

Table-Driven Trigger Policy: Evaluate 3G Volume Quota Group 100 GB

where the ENTITLEMENTS is contained in Match Lists Ent 100GB Quota
set policy context property scenario to 100GB
evaluate policy group QUOTA

The policies in the QUOTA group are now rewritten to use the policy table, which in this case study is named Quota_table, and variables. The sample policies shown previously are rewritten as follows:

Group: QUOTA; Policy: Quota send Warning percent SMS

use table Quota_table called table
where the user is using greater than or equal to table.PctLmt percent and less than 100 percent of volume for table.BaseQuota quota
And where the event trigger is one of USAGE_THRESHOLD_REACHED
send SMS `You have consumed table.PctLmt % of your total quota allotted on Example Inc.` to user. Request delivery receipt `default`.
send notification to syslog with `SMS table.PctLmt%;{User.E164};{User.Custom5};{User.Custom6};GOLD;{User.Entitlement};You have consumed table.PctLmt % of your total quota allotted on Example Inc.` and severity `Info`
Advanced: set values for QoS and Charging parameters to 
Diameter IP-CAN Session Usage Monitoring  USAGE_MONITORING_ENABLED

continue processing message

Group: QUOTA; Policy: Quota additional quota set 100 percent volume threshold

use table Quota_table called table
where the user is using greater than or equal to 100 percent of total volume for table.BaseQuota quota
And where the user is using less than 100 percent of total volume for table.AddlLmt quota
remove PCC rule types all for all
install 16Mbps_DL_5.76Mbps_UL PCC rules for flow
grant total volume to 100 percent used for table.AddlQuota
Advanced: set values for QoS and Charging parameters to 
Diameter Enforcement Session Event Triggers  REVALIDATION_TIMEOUT, USAGE_THRESHOLD_REACHED
Diameter IP-CAN Session Usage Monitoring  USAGE_MONITORING_ENABLED

accept message