Simple Internet Protocol (sip)




Charter



Status: Concluded February, 1994 







Chair(s):



 Steve Deering 



 Bob Hinden 











Description of Working Group:



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The Session Initiation Protocol (SIP) working group is chartered to



continue the development of SIP, currently specified as proposed



standard RFC 2543.  SIP is a text-based protocol, similar to HTTP and



SMTP, for initiating interactive communication sessions between users.



Such sessions include voice, video, chat, interactive games, and



virtual reality. The main work of the group involves bringing SIP from



proposed to draft standard, in addition to specifying and developing



proposed extensions that arise out of strong requirements. The SIP



working group will concentrate on the specification of SIP and its



extensions, and will not explore the  use of SIP for specific



environments or applications. It will, however respond to



general-purpose requirements for changes to SIP provided by other



working groups, including the SIPPING working group, when those



requirements are within the scope and charter of SIP.







Throughout its work, the group will strive to maintain the basic model



and architecture defined by SIP. In particular:







1. Services and features are provided end-to-end whenever possible.







2. Extensions and new features must be generally applicable, and not



   applicable only to a specific set of session types.







3. Simplicity is key.







4. Reuse of existing IP protocols and architectures, and integrating 



   with other IP applications, is crucial.







SIP was first developed within the Multiparty Multimedia Session



Control (MMUSIC) working group, and the SIP working group will continue



to maintain active communications with MMUSIC. This is particularly



important since the main MIME type carried in SIP messages, the Session



Description Protocol (SDP), specified in RFC 2327, is developed by



MMUSIC and because MMUSIC is developing a successor to SDP which SIP







will also use.







The group will work very closely with the (proposed) SIPPING WG, which



is expected to analyze the requirements for application of SIP to



several different tasks, and with the SIMPLE WG, which is using SIP for



messaging and presence.







The group will also maintain open dialogues with the IP telephony



(IPTEL) WG, whose Call Processing Language (CPL) relates to many



features of SIP; will continue to consider the requirements and



specifications previously established by the PSTN and Internet



Internetworking (PINT) working group;: and will consider input from the



Distributed Call Signaling (DCS) Group of the PacketCable Consortium



for distributed telephony services, and from 3GPP, 3GPP2, and MWIF for



third-generation wireless network requirements.







The specific deliverables of the group are:







1. bis: A draft standard version of SIP.







2. callcontrol: Completion of the SIP call control specifications,



   which enables multiparty services, such as transfer and bridged



   sessions.







3. callerpref: Completion of the SIP caller preferences extensions,



   which enables intelligent call routing services.







4. mib: Define a MIB for SIP nodes .5. precon: Completion of the SIP 



   extensions needed to assure satisfaction of external preconditions 



   such as QoS establishment.







6. state: Completion of the SIP extensions needed to manage state



   within signaling, aka SIP "cookies".







7. priv: Completion of SIP extensions for security and privacy.







8. security: Assuring generally adequate security  and privacy 



   mechanisms within SIP.







9. provrel: Completion of the SIP extensions needed for reliability of



   provisional messages.







10. servfeat: Completion of the SIP extensions needed for negotiation



    ofserver features.







11. sesstimer: Completion of the SIP Session Timer extension.







12. events: Completion of the SIP Events extensions (Subscribe/Notify).







13. security: Requirements for Privacy and Security.







14. natfriend: Extensions for making SIP a NAT-friendly protocol.











Other deliverables may be agreed upon as extensions are proposed. New



deliverables must be approved by the Transport Area Directors before



inclusion on the agenda.