Protocols Chương này không cung cấp một Session Initiation Protocol (SIP) đặc điểm kỹ thuật. Thay vào đó, nó sẽ cố gắng chỉ ra những khía cạnh quan trọng của SIP khi họ áp dụng cho các hệ thống con Internet Nghị định thư đa phương tiện (IMS). Đặc biệt, chương này không thảo luận làm thế nào một thực thể SIP nên cư xử bằng cách sử dụng tham số maddr định danh tài nguyên thống nhất (URI) cũng không giải thích làm thế nào các thực thể SIP nên cư xử trong một số các điều kiện lỗi. | Part IV Protocols The IMS IP Multimedia Concepts and Services Second Edition Miikka Poikselka Georg Mayer Hisham Khartabil and Aki Niemi 2006 John Wiley Sons Ltd. ISBN 0-470-01906-9 12 SIP This chapter does not provide a full Session Initiation Protocol SIP specification. Instead it tries to point out the important aspects of SIP as they apply to the Internet Protocol Multimedia Subsystem IMS . In particular this chapter does not discuss how a SIP entity should behave using the maddr parameter in Uniform Resource Identifiers URIs nor does it explain how the SIP entity should behave in certain error conditions. For a full SIP specification please refer to RFC3261 . Background SIP is an application layer protocol that is used for establishing modifying and terminating multimedia sessions in an Internet Protocol IP network. It is part of the multimedia architecture whose protocols are continuously being standardized by the Internet Engineering Task Force IETF . Its applications include but are not limited to voice video gaming messaging call control and presence. The idea of a session signalling protocol over IP dates back to 1992 where multicast conferencing was being considered. SIP itself originated in late 1996 as a component of the IETF Mbone multicast backbone an experimental multicast network on top of the public Internet. It was used by IETF for the distribution of multimedia content including IETF meetings seminars and conferences. Due to its simplicity and extensibility SIP was later adopted as a Voice over IP VoIP signalling protocol finally becoming an IETF-proposed standard in 1999 as RFC2543 . SIP was further enhanced to take into account interoperability issues better design and new features. The actual document was re-written entirely for clarity. The protocol remains mostly backward compatible with RFC2543 . This newly created document became the proposed standard as RFC3261 in 2002 making RFC2543 obsolete. Design principles SIP as part of .
