Session initiation protocol


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Introduction and architecture about Session Initiation Protocol

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Session initiation protocol

  1. 1. Introduction:Session Initiation Protocol (SIP) Aung Thu Rha Hein(g5536871)
  2. 2. Agenda Overview of SIP SIP Functions & Features SIP Architecture  SIP Components  SIP Server Modes Sample SIP call scenario SIP Requests & Responses Protocols used with SIP Summary & Conclusion 2
  3. 3. Overview of SIP A signaling protocol used to create, manage and terminate sessions in IP network A standard protocol defined by IETF IETF mapped it as Application-layer protocol in OSI layer Similar to HTTP & SMTP protocol in syntax  URI: SPI: It is extensible But doesn’t provide end-to-end functionality 3
  4. 4. SIP Functions & Features User Location  Address Resolution: translate URIs to current IP address User Availability  User can control certain types of communication status User Capabilities  Determining the features available by both parties’ programs Session Setup  a three-way handshake Session Management  Able to modify session in use 4
  5. 5. SIP Functions & Features(Cont. ) Registration  Users can register themselves using their ID, independent from the device registration Redirect  SIP server can redirect a request to another address Forking  Request forwarding: Serial & Parallel Forking Proxy  Proxy server can forward the request of the user to another one Mobility  SIP calls can set up if proper gateways are provided 5
  6. 6. SIP Architecture SIP Components  User Agents  Can act as User Agent Client (UAC) and User Agent Server (UAS)  SIP Endpoints: Softphone, SIP phone, Smart Phone, PDA  SIP Servers  Registrar  Authenticate and register UA’s location and status  Proxy  Forward request to other computers. Involve in session setup and teardown  Redirect  Redirect clients to UAs they are attempting to contact. Also can fork a call.  Location Services  A database that used to keep information about users’ registration and their locations 6
  7. 7. SIP Architecture(cont.) SIP Server Modes  Stateful vs Stateless  SIP server can run in one of these two modes  Stateful server keep track of all requests and responses  Stateless server found as part of backbone  Client/server vs P2P 7
  8. 8. Sample SIP call scenario SIP Registration 8
  9. 9. Sample SIP call scenario(cont.) Request through Proxy server 9
  10. 10. Sample SIP call scenario(cont.) Request through Redirect server 10
  11. 11. SIP Requests & ResponsesSIP Request PacketINVITE ”ALICE" <sip:9184249378@>To: <sip:14158867900@>Contact: <sip:9184249378@>Call-ID: 490dffec2cafa2772a11eec8716eCSeq: 102 INVITEUser-Agent: middleserverMax-­­Forwards: 30Allow: INVITE,ACK, CANCEL, OPTIONS, BYE,REFER, SUBSCRIBEContent-Type: application/sdpContent-Length:18011
  12. 12. SIP Requests & Responses SIP Response Packet SIP/2.0 100 Trying (180 Ringing, 200 OK) From: ”BOB" <sip:9184249378@> To: <sip:14158867900@> Call-ID: 490dffec2cafa2772a11eec8716e CSeq: 102 INVITE User-Agent: middleserver Max-­­Forwards: 30 Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBEBYE, REFER, SUBSCRIBE 1xx : Informational 2xx Success: request successful 3xx Redirection : request should tried another location 4xx Client Error: an error in request 5xx Server Error: an error in recipient 6xx Global Failure : request has failed and should not be retried again12
  13. 13. Protocols used with SIP User Datagram Protocol (UDP)  used to send datagrams over IP network Transport Layer Security (TLS)  provides security between applications Session Description Protocol (SDP)  used to send description information when sending multimedia data Real-Time Transport Protocol (RTP)  used to transport real-time data across a network Media Gateway Control Protocol (MGCP)  used to control gateways that provide access to the PSTN Real-Time Streaming Protocol (RTSP)  used to control the delivery of streaming media SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions) 13
  14. 14. Summary & Conclusion A fundamental building block for real-time communication SIP is an open standard and development community is trying for higher interoperability Research going for further enchantments and solutions to known issues 14