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Agenda. Introduction to 3GPP Introduction to SIP IP Multimedia Subsystem Service Routing in IMS Implementation Conclusions. Service routing in 3GPP IP Multimedia Subsystem. Teemu Jalava Supervisor: Raimo Kantola Instructor: M.Sc. Markus Isomäki, Nokia Research Center.

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Presentation Transcript
Agenda
Agenda

  • Introduction to 3GPP

  • Introduction to SIP

  • IP Multimedia Subsystem

  • Service Routing in IMS

  • Implementation

  • Conclusions


Service routing in 3gpp ip multimedia subsystem
Service routing in 3GPP IP Multimedia Subsystem

Teemu Jalava

Supervisor: Raimo Kantola

Instructor: M.Sc. Markus Isomäki, Nokia Research Center


3 rd generation partnership project 3gpp
3rd Generation Partnership Project (3GPP)

  • The 3rd Generation Partnership Project (3GPP) is a collaboration agreement that brings together a number oftelecommunications standards bodies and telecommunications companies.

  • Release ’99 was renamed Release 3

  • Release 4 was out March 2001

    • - IP network

  • Release 5 should be ready in summer 2002

    • - IP multimedia

  • Release 6

    • - All IP network


3gpp network architecture
3GPP Network Architecture

AS


Session initiation protocol sip
Session Initiation Protocol (SIP)

  • Creation, modification and termination of multimedia sessions

  • RCF 2543 -> RCF 3261

  • Request - Reply based transactions

  • Easy to make new extensions

  • ASCII based, clear text, similar to HTTP

  • Uses UDP or TCP

  • URL addressing

    • sip:[email protected]

Client 1

Proxy

Client 2

INVITE

INVITE

100 Trying

180 Ringing

180 Ringing

200 OK

200 OK

ACK

ACK

Media streams

BYE

BYE

200 OK

200 OK



S i p routing
SIP Routing

  • SIP proxy takes care of user location resolving

    • [email protected] -> [email protected]

    • using registrar, DNS (ENUM in case of tel URL) or other means

  • DNS Service Resource Records (SRV RR) can be used to locate a SIP proxy in an other domain

  • via header is needed to ensure packets route the same way back

  • record-route header is needed is sertain proxies need to be in the routing path


Ip multimedia subsystem ims
IP Multimedia Subsystem (IMS)

Call State Control Function (CSCF)

Interrogating-CSCF

  • Accesspoint to domain

  • Hides topology and configuration

(User Agent)

Serving-CSCF

Proxy-CSCF

  • Session control services

  • Registration, AS usage, charging, etc

  • First contact point

  • Provides provicy control and QoS authorization

  • Local services, like emergency calls and local numbering



Application servers
Application servers

  • Using:

    • Call Processing Lanquage (CPL)

    • SIP Common Gateway Interface (CGI)

    • SIP Servets

  • What:

    • Presence

    • Instant Messaging

    • Group services

Roles:

  • SIP proxy

  • redirect server

  • Back-to-back-user-agent (B2BUA)

  • User Agent

    How:

  • Forking

  • SUBSCRIBE - NOTIFY

  • MESSAGE

  • Third party call control


Applic a tion example presence
Application example: Presence

  • Presence enables user to express willingness and availability to communicate

  • Can be used with phonebook to make a "buddy list"

  • Presence updates with REGISTER method

  • Presence download with SUBSCRIBE - NOTIFY


Example of service routing
Example of service routing

Example of service routing


S cscf routing decisions
S-CSCF routing decisions

  • Based of Filter Criteria downloaded from Home Subscriber Server (HSS) at user registration

    • User profile

  • Filter Criteria

    • Address of the Application Server to be contacted.

    • Priority

    • Trigger Points (method, presence or apsence of any header, header content, etc)

    • Default Handling

    • Optional Service Information


Implementation
Implementation

  • Proof of concept work

  • S-CSCF from a SIP proxy

    • Adding filtering

    • Integrated user profile

    • Configuring user profile

  • Testing with network containing Presence AS, redirection AS and SIP-SMSGW


Conclusions
Conclusions

  • SIP based services are easy to make and integrate to the IMS network

  • Configuration is easy

  • Scalable sollution, AS and S-CSCF duplication

  • Release 5 has been delayed from jan 2002 to june 2002, some features have been postponed to Release 6

  • Some pressure from 3GPP to IETF to finalize new SIP RFC and SIP compression

    • These might have some impact to service routing issues


Thank you!

  • Questions?


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