Improving the Routing Efficiency of SIP Instant Message SIP 即時傳訊之繞送效能研究 adviser ： Quincy Wu speaker ： Wenping Zhang date ：

2 Outline Introduction Messaging Schemes  Page-mode SIP/SDP  Session-mode MSRP SIP  Server  Message syntax  Method SDP  Structure Drawback MSRP  Method Future Work Reference

3 Introduction 1/2

4 Introduction 2/2

5 Messaging Schemes 1/2 Page-mode messaging That track only individual messages can be described. Uses the SIP Method MESSAGE for transmitting data. User 1User 2

6 Messaging Schemes 2/2 Session-mode messaging  Messaging that is part of a "session" with a definite start and end.  The new proposed model by SIMPLE work group using MSRP Protocol. MSRP Proxy User 1User 2 SIP

7 Session Initiation Protocol (SIP) A signaling protocol  The setup, modification, and tear-down of multimedia sessions SIP + SDP  Describe the session characteristics Separate signaling and media streams

8 SIP Server Proxy servers  Handle requests or forward requests to other servers  Can be used for call forwarding, time-of-day routing, or follow-me services

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10 SIP Messaging Syntax Text-based  Similar to HTTP  Disadvantage – more bandwidth consumption SIP messages  Message = start-line *message-header CRLF [message-body]

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12 SIP for Instant Messaging The IETF working group – SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE) A new SIP method –MESSAGE (RFC 3428)  This request carries the actual message in a message body.  A MESSAGE request does not establish a SIP dialog.

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14 The Session Description Protocol (SDP) The Most Common Message Body  Be session information describing the media to be exchanged between the parties  SDP, RFC 2327 (initial publication) SIP uses SDP in an answer/offer mode  An agreement between the two parties as to the types of media they are willing to share  RFC 3264 (An Offer/Answer Model with SDP) To describe how SDP and SIP should be used together

15 The Structure of SDP SDP simply provides a format for describing session information to potential session participants. Text-based Protocol The Structure of SDP  Session Level Info Name of the session Originator of the session Time that the session is to be active  Media Level Info Media type Port number Transport protocol Media format

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17 Drawback 1/2 Proxy server Bob Mary

18 Drawback 2/2

19 The Message Session Relay Protocol (MSRP) MSRP is a text-based, connection-oriented protocol for exchanging arbitrary (binary) MIME content, especially instant messages. The exchange is carried by some signaling protocol, such as the Session Initiation Protocol (SIP). This allows a communication user agent to offer a messaging session as one of the possible media- types in a session. SIP can use an offer/answer model to transport the MSRP URIs for the media in SDP.

20 AliceBob INVITE INVITE SIP/2.0 To: From: ;tag=786 Call-ID: 3413an89KU Content-Type: application/sdp c=IN IP4 atlanta.example.com m=message 7654 TCP/MSRP * a=accept-types:text/plain a=path:msrp://atlanta.example.com:7654/jshA7weztas;tcp 200 OK SIP/ OK To: ;tag=087js From: ;tag=786 Call-ID: 3413an89KU Content-Type: application/sdp c=IN IP4 biloxi.example.com m=message TCP/MSRP * a=accept-types:text/plain a=path:msrp://biloxi.example.com:12763/kjhd37s2s20w2a;tcp ACK MSRP Session

21 MSRP communication primitives 1/2 SEND Method  Be used to deliver a complete message or a chunk (a portion of a complete message). src:

22 MSRP communication primitives 2/2 REPORT Method  It report on the status of a previously sent message, or a range of bytes inside a message.

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24 Future Work Joins the MSRP mechanism in existing SIP phone (Linux – Linphone). How solves MSRP passes through NAT the question?

25 Reference RFC SIP: Session Initiation Protocol  RFC Session Initiation Protocol (SIP) Extension for Instant Messaging  RFC SDP: Session Description Protocol  RFC An Offer/Answer Model with the Session Description Protocol (SDP)  The Message Session Relay Protocol 