Diameter S6a interface: SUBSCRIPTION-DATA AVP in IDR message

Question

Based on the 3GPP 29.272, the IDR (Insert-Subscriber-data Request message) is generated by the HSS to the MME to update the subscriber profile in the MME and/or requesting subscriber info such as location-information, subscriber state...
However the SUBSCRIPTION-DATA AVP containing the of profile to be added or updated is defined as Mandatory.
What should contain this AVP if the IDR is sent only for requesting subscriber-info without updating the subscriber profile.
Should ot be present without any nested AVP under it?

Answer 1

Subscription-Data is a mandatory AVP within the IDR command, however sub AVPs of this grouped AVP are optional. So HSS can add Subscription-Data AVP without having any sub AVPs while sending IDR to MME. Specification covers the handling of this scenario.
In this particular case, MME will continue with the stored subscription.
In essence, if Subscription-Data AVP includes any sub AVP then MME considers the new value of that parameter.

Comments

Thank you for your answer.
You mention that the specification covers the handling of this scenario.
Can you indicate the section in the 3GPP specifications describing this specific scenario? (Generating IDR for requesting subscriber-info and without profile update)

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In section 5.2.2.1.2 Detailed behaviour of MME, there is a statement "If the MME or SGSN receives an empty Subscription-Data AVP, it shall take no action with regard to the stored subscription data". Here empty Subscription-Data AVP means not having any sub AVPs.