The p cscf associates the impi given in the

Info icon This preview shows pages 42–44. Sign up to view the full content.

View Full Document Right Arrow Icon
The P-CSCF associates the IMPI given in the registration procedure and all the successfully registered IMPUs related to that IMPI to an SA. A successful authentication proceeds in the following steps: - The P-CSCF receives the SM1 message. If SM1 is protected, it shall be protected with the old inbound SA. - The P-CSCF forwards the message containing the challenge (SM6) to the UE. This shall be protected with the old outbound SA, if SM1 was protected and unprotected otherwise. - The P-CSCF then creates the new SAs, which are derived according to clause 7.1. The expiry time of the new SAs shall be set to allow enough time to complete the registration procedure. The registration SAs shall be deleted if they exist. - The P-CSCF receives the message carrying the response (SM7) from the UE. It shall be protected using the new inbound SA. If SM1 was protected, the old SAs are used to protect messages other than those in the authentication. - The P-CSCF forwards the successful registration message (SM12) to the UE. It shall be protected using the new outbound SA. This completes the registration procedure for the P-CSCF. The P-CSCF sets the expiry time of the new SAs such that they either equals the latest lifetime of the old SAs or it will expire shortly after the registration timer in the message, depending which gives the SAs the longer life. 3GPP 3GPP TS 33.203 V12.67.0 (2014-0609) 42 Release 12
Image of page 42

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
- After SM12 is sent, the P-CSCF handles the UE related SAs according to following rules: - If there are old SAs, but SM1 belonging to the same registration procedure was received unprotected, the P-CSCF considers error cases happened, and assumes UE does not have those old SAs for use. In this case the P-CSCF shall remove the old SAs. - If SM1 belonging to the same registration procedure was protected with an old valid SA, the P-CSCF keeps this inbound SA and the corresponding three SAs created during the same registration with the UE active, and continues to use them. Any other old SAs are deleted. When the old SAs have only a short time left before expiring or a further SIP message protected with a new inbound SA is successfully received from the UE, the P-CSCF starts to use the new SAs for outbound messages with the following exception: when a SIP message is part of a pending SIP transaction it may still be sent over the old SA. A SIP transaction is called pending if it was started using an old SA. The old SAs are then deleted as soon as all pending SIP transactions have been completed, or have timed out. The old SAs are always deleted when the old SAs lifetime are expired. When the old SAs expire without a further SIP message protected by the new SAs, the new SAs are taken into use for outbound messages. This completes the SA handling procedure for the P-CSCF.
Image of page 43
Image of page 44
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern