Section: 19.3.8 Keyname NAI
Content: The keyname NAI shall take the form of an NAI, and shall have the form username@realm as specified in clause 2.1 of IETF RFC 4282 [53]. The username part is the EMSK name as defined in IETF RFC 6696 [113]. For ERP exchange with an ER server located in the 3GPP AAA Server, the realm part of the keyname NAI shall be the realm part of the Root NAI of the UE as described in clause 19.3.2, i.e. the realm part of the keyName-NAI will be in the form: "@nai.epc.mnc<MNC>.mcc<MCC>.3gppnetwork.org" For ERP exchange with an ER server located in the TWAP or in the 3GPP AAA Proxy, the realm part of the keyname NAI shall be the realm discovered by the UE in the non-3GPP access network (received at the lower layer or through an ERP exchange as described in IETF RFC 6696 [113]).