Note 2 in practical deployment a p cscf may have more

Info icon This preview shows pages 121–125. Sign up to view the full content.

View Full Document Right Arrow Icon
ensure that the correct IP address is provided in the SIP message towards the S-CSCF. NOTE 2: In practical deployment, a P-CSCF may have more than one internal interface to extend the capability to hold multiple private networks. NOTE 3: The two solutions here only define the NAT traversal of the GPRS-IMS bundled authentication signaling. Media flow NAT traversal in above cases can be correspondingly solved using the mechanism defined in 3GPP TS 23.228 Annex G [3]. 3GPP 3GPP TS 33.203 V12.67.0 (2014-0609) 121 Release 12
Image of page 121

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

View Full Document Right Arrow Icon
Annex W (normative): Tunnelling of IMS Services over Restrictive Access Networks W.1 Overview This Annex specifies two mechanisms for tunnelling of IMS Services over Restrictive Access Networks. The mechanisms specified in this Annex shall only be applicable when the IP traffic to the IMS core does not traverse through the Evolved Packet Core (EPC). The mechanisms in this Annex are optional to implement. W.2 Service and Media Reachability for Users over Restrictive Firewalls – Tunneled Firewall Traversal for IMS traffic W.2.0General This clause specifies firewall traversal mechanism that can be used for UE access to IMS services. Before using the mechanisms specified in this clause, the UE shall in accordance with normal procedures attempt to use existing NAT/FW traversal mechanisms as specified in TS 23.228 [3] and Annex M of this document. The exact procedure depends on the UE, the access, and operator policy. This mechanism is called Enhanced Firewall Traversal Function (EFTF). Editor’s Note: The functions required for this mechanism need to be detailed further, while re-using functions from the mechanism defined in Annex X.2 of 33.402 as much as possible when applicable. The Enhanced Firewall Traversal Function (EFTF) is not required to implement any ePDG functionality not required for IMS firewall traversal (e.g. authentication, ESP, APN handling, mobility protocols like PMIP). For IMS firewall traversal the S2b, Gxb and SWm reference points from 23.402 is not required. 3GPP 3GPP TS 33.203 V12.67.0 (2014-0609) 122 Release 12
Image of page 122
Figure W.1: Protocol stack for IMS firewall traversal Editor’s note: more textual description of EFTF in line with Figure W.1 is needed to arrive at a complete stage 2 description of the EFTF mechanism. Legend: - As a part of Tunnel Creation, allocation of IP address and negotiation of Keep Alive interval is required. NOTE: The details of how the IP address is allocated and the keep-alive interval is negotiated are in the corresponding stage 3 specification. W.2.1Firewall detection procedure Based on the detection procedure as specified in the following flowchart, it is determined whether it is required to create a TCP/TLS based tunnel to enable the traversal of NIMSFW. 3GPP 3GPP TS 33.203 V12.67.0 (2014-0609) 123 Release 12
Image of page 123

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

View Full Document Right Arrow Icon
Figure W.2: Flowchart for IMS firewall traversal Once the TCP/TLS connection is established, the tunnel creation procedure involves negotiating IP address and keep- alive intervals.
Image of page 124
Image of page 125
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