SIP 逄愛君 [email protected]. SIP&SDP2 Industrial Technology Research Institute...

SIP

逄愛君[email protected]

mailto:[email protected]

SIP&SDP 2

Industrial Technology Research InstituteComputer & Communication Research Laboratories

Elgin Pang

Outline SIP Overview SIP Components SIP Messages SIP Services SDP Conclusion

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SIP Overview Session Initiation Protocol

The signaling protocol for creating, modifying and terminating sessions

Session=audio, video… IETF Proposed Standard (RFC 2543)

February 2, 1999 Currently under development within the Multiparty

Multimedia Session Control (MMUSIC) working group

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SIP Overview 15 Companies test interoperability between their equi

pment April 1999 3Com, Alcatel, Cisco, British, British Telecom, Col

umbia University, Dialogic, Ericsson, HP, Lucent, MCI, Nortel,…

SIP Architecture

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SIP’s Role

to SS7

Signaling Gateway

Signaling Gateway

MediaGateway

Controller

MediaGateway

Controller MGCMGC

SGSG

SIPProxy

SIPProxy

RTP

Megaco

IP Network

to PSTN

SIPsigtran

MediaGateway

MediaGateway Media

Gateway

MediaGateway

SIPClient

SIPClient

sigtran

Megaco

to PSTN

to SS7

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SIP Overview Client-Server Model Flexibility & Extensibility

Text-based Encoding Transport Independence

UDP or TCP Security

Secure Sockets Layer (SSL) for TCP-based SIP

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SIP Components User Agents

Client (UAC) To initiate a SIP request

Server (UAS) To receive the request and return responses

Servers Proxy Redirect Registrar

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Addressing & Naming The entities addressed by SIP are users at host

s email-like identifier of the form user@host

Examples sip:[email protected] sip:[email protected]

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SIP Messages Two kinds of SIP messages

Request and Response Request message format

Request Line Method, Request URI, Version

General, Request, Entity Headers An Empty Line (CRLF)

Indicating the end of the header fields Message Body

Session Description Protocol (SDP) : Optional

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SIP Messages(cont’d)

Response message format Start-line

Status-Line General, Response, Entity Headers An Empty Line (CRLF)

Indicating the end of the header fields Message Body

Session Description Protocol (SDP) : Optional

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Methods INVITE

The user is being invited to participate in a session.

ACK The request confirms that the client has received a

final response to an INVITE request. BYE

The client wishes to release the call.

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Methods (cont’d) OPTIONS

It queries the features the other side supports. CANCEL

It cancels a pending request (not completed request).

REGISTER It conveys the user’s location information to a SIP

server.

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Header Fields General

Apply to both request and response messages Entity

Define information about the message body Request

Allow the user agent client to pass additional information about the request

Response Allow the user agent server to pass additional

information about the response

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SIP HeadersGeneral-headers Entity-headers Request-headers Response-headers

Call-ID Content-Encoding Accept AllowContact Content-Length Accept-Encoding Proxy-

AuthenticationCseq Content-Type Accept-Language UnsupportedDate Authorization Warning

Encryption HideExpires Max-ForwardsFrom Organization

Record-Route PriorityTo Proxy-AuthenticationVia Proxy-Require

RequireResponse-Key

SubjectUser-Agent

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SIP Request Example

INVITE sip:[email protected] SIP/2.0

Via: SIP/2.0/UDP science.fiction.com

From: Fingal <sip:[email protected]>

To: Patric <sip:[email protected]>

Call-ID: [email protected]

Cseq: 1 INVITE

Subject: lunch at La Empenada?

Content-Type: applcation/sdp

Content-Length: …

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Response

1xx Informational Provisional

2xx Success Final

3xx Redirection Final

4xx Client Error Final

5xx Server Error Final

6xx Global Failure Final

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Response (cont’d)100 Continue

180 Ringing

200 OK

300 Multiple Choices

301 Moved Permanently

302 Moved Temporarily

400 Bad Request

403 Forbidden

408 Request Timeout

480 Temporarily Not Available

481 Invalid Call ID

482 Loop Detected

5xx Server Error

600 Busy

604 Does Not Exist

606 Not Acceptable

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SIP Response ExampleSIP/2.0 200 OK

Via: SIP/2.0/UDP sippo.example.se

Via: SIP/2.0/UDP science.fiction.com

From: Fingal <sip:[email protected]>

To: Patric <sip:[email protected]>

Call-ID: [email protected]

Cseq: 1 INVITE

Content-Type: applcation/sdp

Content-Length: …

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Invitation for SIP Proxy

ffl@ fiction.com

science.fiction.com

fiction.com

example.com

location server

sippo

pepperoni(1) INVITE

pgn@ example.se

(7) 200 OK

(8) ACK pgn@ example.se(2

) p

gn

(3)

pg

n@

pep

per

on

i

(4) INVITE pgn@ pepperoni

(6) 200 OK

(9) ACK pgn@ pepperoni

pgn@ pepperoni

(5)

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Invitation for Redirect Server

ffl@ fiction.com

science.fiction.com

fiction.com

example.com

location server

sippo

pepperoni

(1) INVITEpgn@ example.se

(4) 302 Moved temporarilyContact: pgn@ pepperoni.exam ple.se

(5) ACK pgn@ example.se

(2)

pg

n

(3)

pg

n@

pep

pero

ni

pgn@ pepperoni

(6) INVITE pgn@ pepperoni.example.se

(7) 200 OK

(8) ACK pgn@ pepperoni.example.se

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SIP+ISDN (Q.931)

SIP+MGCP

SIP / MGCP / ISUP

Telephone

To SS7

CA CAIAM Create Conn

Invite

Create Conn

ACK IAM

ACMRinging

ACM

ANM200 O K

ACKANM

ACK

Telephone

MGCP

MGCP

GatewayCA

CA

To SS7

Gateway

IP

ACKM odify Conn

G W G W

SS7 SS7M G C P M G C PSIP

R TP Audio

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SIP Services

Similar to the Intelligent Network (IN) services Call Transfer, Call Forwarding, Conference

Calling, User Mobility…

SIP Mobility

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Conclusion SIP is a light-weight signaling protocol. The amount of companies backing SIP is crucia

l for survival. MCI (the biggest backer), 3Com, Lucent and Dy

namicSoft… The low complexity level of the SIP, compared t

o H.323 (H.245 & H.225), should make companies interested.

3G Wireless Technology 3GPP-> H.323 3GIP->SIP

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Discussion

SIP 逄愛君 [email protected]. SIP&SDP2 Industrial Technology Research Institute...

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