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C1-111658
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Reply LS on excessive updates of NAS security context (S3-110529)
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SA3
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To
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Noted
Related Tdocs in C1-111816, C1-111817 and C1-111818.
Answer from SA3 to LS from CT6 (C1-111624).
SA3 thanks CT6 for the LS on excessive updates of NAS security context in (C6-110184 / S3-110341). In this LS CT6 proposed a way forward to solve the problem of excessive writes to the USIM/non-volatile ME memory. The proposed solution is that the ME shall only write the EPS NAS security context to the USIM/non-volatile memory on a state transition from any state to EMM-DEREGISTERED or when an attempt of a state transition away from EMM-DEREGISTERED with the intent to reach EMM-REGISTERED fails.
SA3 has analysed the proposed way forward (see attached discussion paper in S3-110452 for further information). The outcome of SA3's analysis is that it is an acceptable approach.
SA3 has described the process on a stage 2 level as if there are no intermediate states between EMM-DEREGISTERED and EMM-REGISTERED. SA3 understands that there are additional states, but this is a stage 3 detail which is to be taken into account by CT1.
SA3 has agreed the set of CRs attached to this LS (S3-110526, S3-110527 and S3-110528). These CRs implement the same changes to Rel-8, Rel-9 and Rel-10 of TS 33.401. SA3 kindly asks CT1 to implement the corresponding changes to TS 24.301 for Rel-8, Rel-9 and Rel-10.
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