Multimedia Conferencing

with SIP

Orit LevinChief Architect

March, 2003

RADVISION Business

TBU: Enabling TBU: Enabling Technologies Technologies 

Gatekeeper Gatekeeper MGC, …MGC, …

H.324MH.324M

MEGACOMEGACO

NBU: Networking NBU: Networking SolutionsSolutions

GatewayGateway MCU*MCU*

Servers,Servers,

FW Solutions,…FW Solutions,…

VideoVideoSIPSIP

MGCPMGCP

*MCU= Multiparty Conferencing Unit

H.323H.323

Videoconferencing Network

IP Network

PSTN/ISDN

Wireless 3G/

H.324M

Gateway

GatewayMCU

RADVISION ProductsRADVISION Products

RADVISION TechnologyRADVISION Technology

Gatekeeper/Proxy

RADVISION SIP strategy RADVISION is the leading provider of SIP-

based technologies SIP protocol stack SIP developer tools (proxy, registrar)

RADVISION is pushing for standards Standards for Video Standards for Conferencing

Seamless Protocol Integration with providing full support for all of the existing features of our product line RADVISION supports SIP, H.323 (IP), H.320

(ISDN), H.324M (3G)

What Does it Taketo Have a MultimediaSIP Conference?

Building Blocks

Point-to-Point Call Control Baseline SIP/SDP

Point-to-Point Media Control Video

SIP “Advanced” Call Control SIP conferencing extensions (Optional) Refer Method (Optional)

Conference Control Participants Control Floor Control (Optional)

Point-to-Point Basic Media Description Mechanism RFC 3264 “An Offer/Answer Model with

SDP” Change Media Characteristics by

“Re-INVITE” (or “UPDATE”) Hold/Resume Media Stream

Advanced Scenarios Examples Draft Under definition Will use “Grouping of Media Lines in the SIP”

RFC 3388 Will use “'SDP Simple Capability Declaration'

draft-andreasen-mmusic-sdp-simcap-05.txt

Video support in SIP

“Freeze Picture” Command (Encoder -> Decoder) “Fast Update” Command (Decoder -> Encoder)

* “CODEC” = enCOder DECoder

Two Basic Video Controls

XML Schema in INFO

The IETF draft

“draft-levin-mmusic-xml-media-control-01.txt “

Implemented already by ViaIP MCU (RADVISION) RTC Messenger (Microsoft) eConf (France Telecom)

Tech Currently defines “Fast Update” and “Freeze

Picture” Transported over SIP INFO

SIP forConferencing

SIPPING Conferencing Design team in IETF

SIPPING Requirements Document

SIPPING Framework Document

SIPPING Conference Event Package (NOTIFYs of participant list)

SIPPING Call Control – Conferencing Usage Document

Documents listed at http://softarmor.com/sipping/teams/conf/

SIP Tightly Coupled Conference

Association of User Agents with a single central point – i.e. Focus.

Focus is a UA that Maintains a SIP dialog with each

conference participant and internally correlates among them.

Can be implemented either by a participant or by a dedicated server.

In centralized model, focus does media mixing

In decentralized model, focus controls endpoint mixing

SIP Conference Identification

A SIP Conference is uniquely identified by a globally routable Conference URI.

Focus includes the Conference URI (followed by the feature tag “isfocus”) in the Contact of each message belonging to a conference dialog.

As a result, any RFC 3261 compliant UA can participate in a conference.

A Conference and its URI Exist

Dial In User’s INVITE carries the Conference URI in the

Request-URI. Server’s 200 OK carries the Conference URI in the

Contact.

Dial Out Server’s INVITE carries the Conference URI in the

Contact. Conference-aware user understands the meaning

of “isfocus” feature tag.

Additional Participants Can be added by sending a REFER with the Refer-

To of the Conference URI.

Ad-Hoc Conference Creationusing Conference Factory URI

Definition: an INVITE sent to this SIP URI will “create” an ad-hoc conference.

Conference Factory URI can be programmed on a “Conference” button on a SIP phone, or published on a webpage.

The new Conference URI is returned to the creator in the Contact in the 200 OK.

Participants’ List

“SIP Event Packages for Call and Conference”

draft-rosenberg-sip-call-package-00.txt The Body of NOTIFY Contains a

Conference Information XML Document of MIME Type application/conference-info+xml

List of Users User Identity Status active|departed|booted|failed Etc.

Non-SIP Further PotentialConferencing work in IETF

Conference Policy Control Protocol (CPCP)

Used to create conferences by automata

Used by conference owner to change policies

Media Policy Control Protocol (MPCP) Users control how media is

mixed/presented

Floor Control Protocol

RADVISIONSIP ConferencingSolution

Multimedia Centralized Conferencing

MCU is a SIP User Agent The Conferencing Functions are

Implemented by the MCU whenever possible Mixing of Media Streams Conferencing and Floor Control

The Easiest Task from End User Perspective Looks Like a Point-to-Point Call with the MCU Does not Necessarily Require Special

Conferencing Support

Addressing the Scalability Issue

To Make the Solution More Scalable, the MCUs can be further cascaded

It is Transparent to the End Users

ISDN/CSN

Multimedia Centralized Conferencing

Mobile Phone

PSTN Phone

MS Messenger SIP Videophone H.323 Application

H.320 System

Internet

Video and VoiceMCU

SIP Phone

MCU Key Features Voice Activated or Continuous Presence modes Video Algorithms - H.261,H.263, H.263++ Audio Algorithms – G.711, G.722, G.728,

G.723.1, G.729 A/B, Siren/G722.1

Web based Administration and Conference Control

XML Based 3rd Party Call Control API Video Transcoding Resolution: CIF, QCIF, 4CIF T.120 Data Collaboration

Some features require optional hardware/software

WEB Conferencing and Floor Control

RADVISION’s XML-basedOpen API:

Create/Terminate Conference

Take/Release Conference Control

Invite/Disconnect Participant

Get Conference List and details

Get Number Of Participants In Conference

Get Participant Details

Get Conference Video Configuration

Lock/Unlock Participant Video

Mute/Enable Audio Channel

Conferencing Control API

IM1st Ad-hoc Conferencing

Integration with the Microsoft RTC Conference initiation by adding a

“Conference Assistant” Buddy to the IM chat

Existing conference control Video window is logically attached to

multiparty IM

IMst – I

IM1st – II

IM1st – III

Thank You

www.radvision.comorit@radvision.com