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Request Construction

Diameter Request Construction

When constructing Diameter messages to send, the DSG-SCP is able to modify the values of core AVPs and include additional AVPs as required.

Request configuration has several sub-sections:

A sample Diameter request configuration might be:

    <application name="<application instance name>" module="DsgScpApp">
      ...
      <config>
        <diameter>
          ...
          <request>
            <service_identifiers>
              <rule literal="1" tag="network" value="home" />
              <rule literal="2" tag="network" value="national_roaming" />
              <rule literal="3" />
            </service_identifiers>

            <rating_groups>
              <rule literal="10" tag="bearer" value="voice" />
            </rating_groups>

            <requested_times />

            <service_context_ids>
              <rule literal="n2dsg_test@nsquared.nz"/>
            </service_context_ids>

            <additional_mscc_avps />

            <additional_root_avps>
              <avp code="873" vendor_id="10415"> <!-- Service-Information -->
                <avp code="876" vendor_id="10415"> <!-- IMS-Information -->
                  <avp code="831" vendor_id="10415" idp="callingPartyNumber_digits_n" /> <!-- Calling-Party-Address -->
                  <avp code="832" vendor_id="10415" idp="calledPartyNumber_digits_n" /> <!-- Called-Party-Address -->
                </avp>
                <avp code="3410" vendor_id="10415"> <!-- VCS-Information -->
                  <avp code="3412" vendor_id="10415" idp="bearerCap_itc" /> <!-- Bearer-Capability -->
                  <avp code="3417" vendor_id="10415" from_tag="msc" /> <!-- MSC-Address -->
                  <avp code="3420" vendor_id="10415" from_tag="vlr" /> <!-- VLR-Number -->
                  <avp code="3414" vendor_id="10415" from_tag="location" /> <!-- ISUP-Location-Number -->
                </avp>
              </avp>
            </additional_root_avps>

          </request>
          ...
        </diameter>
        ...
      </config>
      ...

This configuration would construct Diameter requests with the following characteristics:

Configuration Details

The config → diameter → request configuration block holds configuration for the specific handling that is applied to build and send Diameter messages to the OCS. The available element attributes and children are:

Attribute Type Description
service_identifiers Array Holds the rules that are applied to determine the value of the Diameter Service-Identifier AVP. If not present, or if no rules are specified, no Diameter Service-Identifier will be sent to the OCS.
.rule Object Provisions a Selector Rule for setting the value of the Diameter Service-Identifier AVP.
rating_groups Array Holds the rules that are applied to determine the value of the Diameter Rating-Group AVP. If not present, or if no rules are specified, no Diameter Rating-Group will be sent to the OCS.
.rule Object Provisions a Selector Rule for setting the value of the Diameter Rating-Group AVP.
requested_times Array Holds the rules that are applied to determine the value of the Diameter Requested-Service-Unit → CC-Time AVP. If not present, or no rules are specified, the diameter_default_rsu_seconds application parameter value will be sent to the OCS in Diameter Requested-Service-Unit → CC-Time AVPs.
.rule Object [Required] Provisions a Selector Rule for setting the value of the Diameter Requested-Service-Unit → CC-Time AVP.
service_context_ids Array Holds the rules that are applied to determine the value of the Diameter Service-Context-Id AVP.
.rule Object [Required] Provisions a Selector Rule for setting the value of the Diameter Service-Context-Id AVP. If not present, or no rules are specified, the diameter_default_service_context_id application parameter value will be sent to the OCS in Diameter Service-Context-Id AVPs.
additional_mscc_avps Array Holds the additional AVP definitions that are added at the end of the Diameter Multiple-Services-Credit-Control AVP.
.avp Object [Required] Provisions a single additional AVP definition for freeform AVP inclusion in the Diameter Multiple-Services-Credit-Control AVP.
additional_root_avps Array Holds the additional AVP definitions that are added at the end of the Diameter request.
.avp Object [Required] Provisions a single additional AVP definition for freeform AVP inclusion in the Diameter request.

Additional AVP Definitions

Within the additional_mscc_avps and additional_root_avps blocks, an AVP tree can be specified for inclusion within Diameter request messages that are constructed.

Each avp definition may be either a leaf AVP, containing a source value, or may contain other avp definitions. AVPs are added in the order listed.

If a source value for an AVP does not have a value (e.g. the network did not provide it), the AVP will not be sent. Grouped AVPs with other AVPs as their children must have at least one child present to be sent. An AVP may be marked as mandatory, in which case a failure to populate it will reject the message that is being constructed.

Additional AVPs at the MSCC level are not sent if there is no Diameter Multiple-Services-Credit-Control AVP sent, e.g. if MSCC is not enabled via configuration or the message is terminating a root session without MSCC.

Note that all AVPs listed for inclusion must be pre-configured in the N2SVCD Diameter codec. Refer to the N2SVCD technical guide for details.

The available element attributes and children for each avp definition are:

Attribute Type Description
code String [Required] The AVP code for this AVP definition. The combination of the code and vendor_id must be configured in the N2SVCD Diameter codec.
vendor_id String The Diameter Vendor-Id for this AVP definition, if required. The combination of the code and vendor_id must be configured in the N2SVCD Diameter codec.
(Default = 0, IANA AVP code values).
literal String [Conditional] A literal value to use as the source value for this AVP. One of literal, idp, or from_tag must be present for each AVP definition that is not a grouped AVP.
idp String [Conditional] An available field from the InitialDP to use as the source value for this AVP. Multiple fields may be separated by a comma, and will be concatenated (if populated). One of literal, idp, or from_tag must be present for each AVP definition that is not a grouped AVP.
from_tag String [Conditional] A tag to use as the source value for this AVP. Multiple tags may be separated by a comma, and will be concatenated (if populated). One of literal, idp, or from_tag must be present for each AVP definition that is not a grouped AVP.
r_index Integer For idp and from_tag source selection, r_index can be used to specify the starting index for value retrieval. Positive values count from the start of the string (zero-indexed), and negative values count from the end. Used in conjunction with r_len to provide any substring of the selected value, including prefix or suffix.
(Default: 0, copy from the start of the string)
r_len Positive Integer For idp and from_tag source selection, r_len can be used to specify the returned length of the selected value. Used in conjunction with r_index to provide any substring of the selected value, including prefix or suffix.
(Default: the selected value's remaining length after r_index has been applied)
mandatory Boolean Whether this AVP must be included in outbound messages or not. If false, if the AVP cannot be populated with a source value or with AVP children, the AVP will not be included in the sent Diameter request. If true and the AVP cannot be populated from, the Diameter request will not be sent.
Note that this does not apply to AVPs that are deliberately not populated due to configured filter conditions, e.g. at_initial.
(Default = false, allow request without this AVP).
edr String If provided, the AVP's populated value will be written to EDRs produced in the field named. Note that the EDR field will not be filled if any of the following apply:
  • the AVP cannot be populated from the source indicated
  • the AVP is not included due to rule filtering
  • the AVP is grouped (i.e. contains children)
  • no Diameter was sent (e.g. failure during mandatory tag population)
  • the containing Multiple-Services-Credit-Control AVP was not sent due to root session closure
tag String [Conditional] A tag name to require a specific value for to trigger population of the AVP. If tag is present, value> must also be present.
tag_x String [Conditional] As for tag, but with x representing a unique pairing, e.g. tag_1 or tag_a. A matching value_x must also be present.
value String [Conditional] The string or integer value to match against during AVP population. Required when tag is present.
value_x String [Conditional] As for value, but with x representing a unique pairing, e.g. value_1 or value_a. A matching tag_x must also be present.
originating Boolean Whether this AVP should be included for requests for originating calls
(Default: true)
forwarding Boolean Whether this AVP should be included for requests for forwarding calls.
(Default: true)
terminating Boolean Whether this AVP should be included for requests for terminating calls.
(Default: true)
at_initial Boolean Whether this AVP should be included at the initial OCS interrogation, i.e. the Diameter CC-Request-Type is 1 (INITIAL_REQUEST).
(Default: true)
at_update Boolean Whether this AVP should be included at interim OCS interrogations, i.e. the Diameter CC-Request-Type is 2 (UPDATE_REQUEST).
(Default: true)
at_terminate Boolean Whether this AVP should be included at the final OCS interrogation, i.e. the Diameter CC-Request-Type is 3 (TERMINATE_REQUEST).
(Default: true)
(other available fields) (various) Any number of selector rule available fields.