Question

Why Diameter server(AAA) is needed for authentication - authorizaion messages AAR , AAA, ACR, ACA messages in order to authenticate if authentication/security is done at MME/eNB/HSS while attach.? Could you please explain in detail?

Answer 1

Authentication and Authorization is done through MME but details are provided by HSS to MME.
For UE, MME is an anchor point to do all procedures like authentication, default bearer and dedicated bearer creation. It is not necessary MME talks only to home HSS, it talks to other network HSS for the roaming users. Some authentication and authorization should be in place.

Comments

thanks ganesh, but If Authentication and Authorization is done through MME then Why diameter (AAA) server is used for authentication and authorization from PGW?
PGW is connected with AAA server over SGI interface.

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Its for eHRPD users for that authentication is required by using proxy Radius Server which then acts as an agent to forward request to 3GPP2 Radius Server as in HRPD/EvDO. For normal LTE users there is no role of Diameter AAA, its used only when LTE/CDMA handoff is required.

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WiFi calling. There is no mme