Content Filtering and X-Header Enrichment

Revision History

Table 1. Revision History

Revision Details

Introductory Release

First introduced.

Pre-2020.02.0

Functions of content filtering

The Content Filtering (CF) service prevents subscribers from accidentally accessing unacceptable content, or inappropriate content based on subscriber preferences.

The CF service filters HTTP and WAP requests from mobile subscribers based on the URLs in the subscriber requests.

Operators can control and filter the content accessible to an individual subscriber.

Configure content filtering

This section describes how to configure content filtering.


Important
Apart from these configurations, all other configurations are used only in the UPF, and SMF sends it to the UPF. The SMF doesn't use these configurations. For more information on how to enable the feature on UPF, see the UCC 5G UPF Configuration and Administration Guide.

Procedure

Step 1

Define the active-charging service name in global configuration mode to configure content filtering under the active charging service.

active-charging service service_name

Example:

[smf] smf(config)# active-charging service acs

Step 2

Define rulebase name to configure content filtering under rulebase.

rulebase rulebase_name

Example:

[smf] smf(config-service-acs)# rulebase rule1

Step 3

Specify the CF policy number.

content-filtering category policy-id cf_policy_id

Example:

[smf] smf(config-rulebase-rule1)# content-filtering category policy-id 32

The value of cf_policy_id must be an integer in the range of 1 to 4294967295.

Step 4

Define apn name and CF policy number to configure content filtering under apn. Save the configuration and commit the changes.

apn apn_name

Example:


[smf] smf(config)# apn isp1 
[smf] smf(config-apn-isp1)# content-filtering category policy-id 101

The value of cf_policy_id must be an integer in the range of 1 to 4294967295.

Content filtering policy ID on N7 interface

The CF categories are configured under the active charging service with specific policy IDs. The rulebase and APN also have an associated policy ID. Only one policy ID can be associated with a session at any time. The categories configured under that CF policy ID are applicable for the session on the UPF.

The PCF can override the CF policy ID by sending this value on the N7 interface. A proprietary IE available in the YAML definition for the N7 interface facilitates this process.

The hierarchy for the CF policy ID is structured as:

smPolicyDecision 
   ciscoAvpSet: 
      cfPolicyId: uint32 value

When the PCF does not send a CF policy ID, the existing CF policy ID in the rulebase configuration or the policy ID configured in the APN configuration is selected, in the order of precedence. This CF policy ID value is sent to the UPF in the PFCP Session Establishment Request message in the "Subscriber Parameters" attribute. During PDU Session Modification, if the PCF changes the CF policy ID, the ID is sent to the UPF in the PFCP Session Modification Request message.

X-Header enrichment

X-Header insertion and X-Header encryption features are collectively known as X-Header enrichment.

X-Header enrichment is a feature that:

  • allows appending headers to HTTP or WSP GET and POST request packets

  • adds headers to HTTP response packets for use by end applications,

  • such as mobile advertisement insertion (for example, MSISDN, IMSI, IP address).

X-Header information

Certain X-header configurations need the SMF to send relevant values to the UPF.

The table describes information sent from SMF to UPF for X-header insertion.

Table 2. X-header information description
Xheader Field Description Present in Session Establishment Modified in Session Modification
String Constant Inserts the configured string in X-header — —
Charging ID Per Flow or Bearer Charging Id Yes —
IMEI IMEI for the call Yes —
IMSI IMSI for the call Yes —
Rat-Type RAT type for the UE session Yes Yes
s-mcc-mnc MCC or MNC of the SGW or AMF Yes —
Sgsn-address AMF or SGW address Yes Yes
ULI User Location Info Yes Yes
GGSN-Address N4 or or S5 endpoint of SMF Yes Yes
Radius-station-ID MSISDN of the UE — —
Sn-rulebase Rulebase for a call Yes Yes
Subscriber-ip-address IP address allocated to UE — —
Msisdn-no-cc Obtained from MSISDN Yes No

The subscriber-specific fields—IMSI, MSIDN, and IMEI—are encoded in the "User ID" standard IE. For more information, refer to 3GPP 29.244, Section 8.2.101.

Rest of the fields are sent in the "Subscriber Parameters" proprietary AVP. Some fields, such as the "Rulebase" and "UE IP address", are sent as a part of the created PDRs.


Important

  • All parameters are consistently sent from the SMF to the UPF, regardless of the availability of X-header configurations. These parameters ensure that any change in configuration after session creation is immediately applied on the UPF.

  • The SMF supports X-header insertion-related configurations. The SMF does not require these configurations for its functionality. These configurations are sent to the UPF.