Private Header (P-Header) Extension to the Session Initiation Protocol (SIP) for Authorization of Early Media
RFC 5009
Document | Type |
RFC - Informational
(September 2007; No errata)
Was draft-ejzak-sipping-p-em-auth (individual in gen area)
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Author | Richard Ejzak | ||
Last updated | 2015-10-14 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 5009 (Informational) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Jon Peterson | ||
Send notices to | (None) |
Network Working Group R. Ejzak Request for Comments: 5009 Alcatel-Lucent Category: Informational September 2007 Private Header (P-Header) Extension to the Session Initiation Protocol (SIP) for Authorization of Early Media Status of This Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Abstract This document describes a private Session Initiation Protocol (SIP) header field (P-header) to be used by the European Telecommunications Standards Institute (ETSI) Telecommunications and Internet-converged Services and Protocols for Advanced Networks (TISPAN) for the purpose of authorizing early media flows in Third Generation Partnership Project (3GPP) IP Multimedia Subsystems (IMS). This header field is useful in any SIP network that is interconnected with other SIP networks and needs to control the flow of media in the early dialog state. Ejzak Informational [Page 1] RFC 5009 P-Early-Media Header September 2007 Table of Contents 1. Introduction ....................................................2 2. Applicability Statement .........................................3 3. Conventions and Acronyms ........................................3 4. Background on Early Media Authorization .........................4 4.1. Backward Early Media .......................................5 4.2. Forward Early Media ........................................5 5. Applicability of RFC 3959 and RFC 3960 ..........................6 6. Overview of Operation ...........................................6 7. Limitations of the P-Early-Media Header Field ...................8 8. The P-Early-Media Header Field ..................................8 8.1. Procedures at the User Agent Client .......................10 8.2. Procedures at the User Agent Server .......................10 8.3. Procedures at the Proxy ...................................11 9. Formal Syntax ..................................................11 10. Security Considerations .......................................11 11. IANA Considerations ...........................................12 11.1. Registration of the "P-Early-Media" SIP Header Field .....12 12. Acknowledgements ..............................................12 13. References ....................................................12 13.1. Normative References .....................................12 13.2. Informative References ...................................13 1. Introduction This document defines the use of the P-Early-Media header field for use within SIP [1] messages in certain SIP networks to authorize the cut-through of backward and/or forward early media when permitted by the early media policies of the networks involved. The P-Early-Media header field is intended for use in a SIP network, such as a 3GPP IMS [13][14] that has the following characteristics: its early media policy prohibits the exchange of early media between end users; it is interconnected with other SIP networks that have unknown, untrusted, or different policies regarding early media; and it has the capability to "gate" (enable/disable) the flow of early media to/from user equipment. Within an isolated SIP network, it is possible to gate early media associated with all endpoints within the network to enforce a desired early media policy among network endpoints. However, when a SIP network is interconnected with other SIP networks, only the boundary node connected to the external network can determine which early media policy to apply to a session established between endpoints on different sides of the boundary. The P-Early-Media header field provides a means for this boundary node to communicate this early media policy decision to other nodes within the network. Ejzak Informational [Page 2] RFC 5009 P-Early-Media Header September 2007 2. Applicability Statement The use of this extension is only applicable inside a "Trust Domain" as defined in RFC 3325 [6]. Nodes in such a Trust Domain are explicitly trusted by its users and end-systems to authorize early media requests only when allowed by early media policy within the Trust Domain. This document does NOT offer a general early media authorization model suitable for inter-domain use or use in the Internet at large. Furthermore, since the early media requests are not cryptographically certified, they are subject to forgery, replay, and falsification in any architecture that does not meet the requirements of the TrustShow full document text