A p cscf is said to be pani aware if it handles p

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A P-CSCF is said to be “PANI-aware” if it handles P-Access-Network-Info headers as follows: - A “PANI-aware” P-CSCF shall insert a P-Access-Network-Info header containing the "network-provided" parameter and remove any such header containing the "network-provided" parameter sent by the UE if the REGISTER request was received over a TISPAN NASS. - A “PANI-aware” P-CSCF may insert a P-Access-Network-Info header containing the "network-provided" parameter and shall remove any such header containing the "network-provided" parameter sent by the UE if the REGISTER request was not received over a TISPAN NASS. P-Access-Network-Info headers are used by the S-CSCF to distinguish REGISTER requests relating to GIBA from REGISTER requests relating to NBA and SIP Digest, which do not necessarily use an Authorization header in the initial REGISTER request, cf. Annex P.4.2 of this specification. This motivates the following rule: 3GPP 3GPP TS 33.203 V12.67.0 (2014-0609) 91 Release 12
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- Under the additional conditions that the REGISTER request contains no Authorization header and was received over an access network other than TISPAN NASS or 3GPP it is even mandatory for the P-CSCF to insert a P-Access-Network-Info header containing the "network-provided" parameter. NOTE 4: For the purposes of NBA, the P-CSCF includes NASS location information in the P-Access-Network- Info header. But, according to TS 24.229 [8], the P-CSCF handles any P-Access-Network-Info header included by the UE transparently, and, hence, an S-CSCF could receive a P-Access-Network-Info header with false NASS location information inserted by the UE even when the access network is not a TISPAN NASS. This would negatively impact the security of NASS-IMS-bundled authentication. Therefore, the removal of a P-Access-Network-Info header with the "network-provided" parameter is mandated for PANI-aware P-CSCFs even when the access network is not a TISPAN NASS. How the P-CSCF knows the access network type of a specific network interface is implementation-dependent (e.g. it can know the access network type from different UE IP address ranges or by using different network interfaces for different access network types). NOTE 5: The P-CSCF is not in the path for all authentication techniques. For example, for TNA the Trusted Node communicates directly with the I-CSCF. P.4 Determination of requested authentication scheme in S-CSCF P.4.1 Stepwise approach When receiving a REGISTER request the S-CSCF distinguishes among authentication methods using the following three steps. How these steps are performed is described in subclause P.4.2. - Step 1: the S-CSCF first checks whether the IMS REGISTER request relates to IMS AKA or not. In the case of IMS AKA, the S-CSCF shall behave according to this specification. Otherwise, the S-CSCF proceeds to step 1a.
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