XCON BOF R. Even Internet-Draft Polycom Expires: December 21, 2003 N. Ismail Cisco Systems, Inc. June 22, 2003 Conferencing Scenarios draft-even-xcon-conference-scenarios- 00.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on December 21, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document describes SIP conferencing scenarios. It will describe basic and advance conferencing scenarios. These conferencing scenarios will help with definition and evaluation of the requirements for SIP conferencing framework. Even & Ismail Expires December 21, 2003 [Page 1] Internet-Draft Conference Scenarios June 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Simple Conferencing scenarios . . . . . . . . . . . . . . . . 3 2.1 Ad-hoc conference . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Extension of a Point to point calls to a multipoint call . . . 4 2.3 Reserved conference . . . . . . . . . . . . . . . . . . . . . 4 3. Advance Conferencing scenarios . . . . . . . . . . . . . . . . 4 3.1 Extending a point-to-point call to a multipoint call . . . . . 4 3.2 Lecture mode conferences . . . . . . . . . . . . . . . . . . . 5 3.3 Conference with non-SIP members . . . . . . . . . . . . . . . 5 3.4 A reserved or ad-hoc conference with conference aware members. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.5 Advanced conference features . . . . . . . . . . . . . . . . . 5 4. Scenarios for media policy control . . . . . . . . . . . . . . 7 4.1 Video mixing scenarios . . . . . . . . . . . . . . . . . . . . 7 4.2 Typical video conferencing scenario . . . . . . . . . . . . . 8 4.3 Conference Sidebar scenario . . . . . . . . . . . . . . . . . 9 4.4 Coaching scenario . . . . . . . . . . . . . . . . . . . . . . 9 4.5 Presentation and QA session . . . . . . . . . . . . . . . . . 10 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . 12 Even & Ismail Expires December 21, 2003 [Page 2] Internet-Draft Conference Scenarios June 2003 1. Introduction This document describes SIP conferencing scenarios. It will describe basic and advance conferencing scenarios. These conferencing scenarios will help with the definition and the evaluation of the requirements for SIP conferencing framework. The advanced scenarios will assume the UA functionality based on relevant SIP RFCs that will be needed in order to participate in the conference and take advantage of the conference functionality. The entities composing the conference will be the "focus" that is the center point for signaling and the members. A special member is the member who initiated the conference. The scenarios described are to demonstrate different conferencing services that can be offered in the SIP environment that will benefit from having some support in the UAs that will enable more robust and easier to use conferencing services. It will be up to the conferencing bridge manufacturers and the service provider to decide what services can be built and which services will be offered to the end users. 2. Simple Conferencing scenarios These scenarios will assume a UA that support basic SIP functionality as described in RFC3261[1] and RFC3264 [2] . The reason for these scenarios is to enable a basic UA without any specific conferencing extensions to create, join and participate in a conference. The UA may use an out of band signaling to participate in a conference but this is not a mandatory requirement. The focus will have all the functionality it needs in order to supply the service offered to the members. The UA shall be able to provide DTMF tones. 2.1 Ad-hoc conference A user has a service provisioned to him that enables him to start an ad-hoc conference when he calls the focus. When the member wants to start a conference he calls the conference service. The member may be identified by different means including the called number, the calling number or an IVR system using in-band DTMF tones. The conference is created automatically with the predefined functionality. The member who has such a service notifies the other participants how to call the conference via an external mean like email. The member may have the functionality of a focus and thus can create ad-hoc conference using his own UA functionality. An example of such a conference is an audio conference initiated by one of the members who has a conference service that enables him to start a conference when he calls a specific number (or URI). The conference may be created by the first person calling this number or it may be created only after the owner is authenticated using an IVR system, the other participants may get an announcement and are placed on hold Even & Ismail Expires December 21, 2003 [Page 3] Internet-Draft Conference Scenarios June 2003 if they call the conference before the owner. 2.2 Extension of a Point to point calls to a multipoint call This is a simple case. The initiating member is in a call with one party and wants to add another party to the call. The initiating member cannot handle the focus on his UA nor can the other member. Both of them cannot support call transfer. The way to do this conference is by disconnecting and using the above method. The information about the conference will be conveyed in the point-to-point call. The focus may support dial out allowing the initiating member to call the third party. 2.3 Reserved conference The reservation was done by out of band mechanism. The conference identification is allocated by the reservation system. It is sent to all participants. The participants join using the conference identification. The conference identification must be routable enabling the allocation of a focus with free resources at the time when the conference will actually run. The focus can also dial out to the conference members. The UAs will not be aware that they are in a conference. The participants may know via announcement from the conference that they are in a conference and who are the other members 3. Advance Conferencing scenarios These scenarios will assume UAs that support at least call transfer service and a way to communicate information on events from the focus to the UA. The focus will be able to know the capabilities of the members to identify if they support the call transfer. The section will specify in each scenario the dependencies. An advance conference can be initiated by a UA that has advanced features but some UAs in the conference may have lesser functionality. 3.1 Extending a point-to-point call to a multipoint call The initiating member is in a point-to-point call and want to add a third member. The initiating member can start a multipoint call on a conferencing bridge known to him. The extension can be without consultation, which means that he moves the point-to-point call to the focus and then adds the third party (this can be done in various ways). The extension can be done with consultation, which means that he puts his current party on hold calls, the third party and asks him to join the conference and then transfers all the members to the conferencing bridge. Even & Ismail Expires December 21, 2003 [Page 4] Internet-Draft Conference Scenarios June 2003 3.2 Lecture mode conferences This conference scenario enables a conference with a lecturer that present a topic and can allow questions. The lecturer needs to know who are the participants and to be able to give them the right to speak. The right to speak can be based on floor control but can also be based on out of band mechanism. 3.3 Conference with non-SIP members A focus can include participants that are not SIP UAs that are joining the focus via a gateway function. Those members may be basic participants or the GW function will proxy the advanced functionality between the different protocols and the SIP focus. 3.4 A reserved or ad-hoc conference with conference aware members. The initiating member will call the focus using for example a unique identifier in order to start the conference. The focus may use some authenticating method to qualify the member. The other participants may call the focus and join the conference. The focus will be able to find the capabilities of the members. In case of a reserved conference the focus will start the conference at the scheduled time. The members may join by call the conference ID or the focus may call them. The conference may have privilege levels associated with a specific conference or member. The privileges will be for the initiating member and for a regular member; the initiating member may delegate privileges to the other members. The privileges will allow functionality as defined in the next section. 3.5 Advanced conference features The following scenarios can be used in all the advance conferencing scenarios. In the examples given in this section, when referring to a member that has a functionality it means a member with the right privileges. These scenarios may be available in the advanced conferencing scenarios and are common in many conferencing applications. These are not a requirement list but some examples of how specific functionality is being used in a conference. Add Participants - A member may add a new member to the focus. This can be done, for example, by instructing the focus to call the participant or by the member calling the participant and pointing him to the conference. The member may delete participants from the focus if he can identify them. Authenticate participants - A member can authenticate members that want to join the focus. This can be done implicitly by assigning a Even & Ismail Expires December 21, 2003 [Page 5] Internet-Draft Conference Scenarios June 2003 password to the conference and letting the focus authenticate the new members or explicitly by directing the authentication requests to the initiating member who will authenticate each user. Controlling the presentation of media - during the conference the member may be able to manage whose media is being sent to each participant. For example the member may be able to decide that he wants to be the speaker and all the rest are listeners he may also specify whose media he wants to receive. The member may be able to mute a media stream during the conference. Giving privileges - the member may want, during the conference, to give a privilege to another member. The assigning of privileges may be implicit when requested or explicit by asking the member to grant a privilege. Side conferences or sidebars - the member may want to create a side conference that include some of the participants and when the side conference is done the members will return to the main conference. A side bar may have the same functionality as the main conference. There can be some sidebars scenarios. The simple one will be based on capabilities of two participants to have two calls at the same time and they will have a point to point call in parallel to the main conference, it is an end point implementation to decide if to mix both calls streams or to enable the user to switch between them. The sidebar scenario that will use the focus will use the same call he is in and let the focus create the sidebar and compose the relevant sidebar stream mixes. These mixes can include the main conference as an incoming stream to the mix. The way to signal the creation of the sidebar and how to invite members and control the mixes should be available. Focus information - When a member joins the focus he is announced to the members. An announcement may be available when he leaves the focus. The members may query the focus for its current members. Extending of a conference - Reserved conferences and ad-hoc conferences may have a time limit. The focus will inform the members when the limit is close and may allow the extension of the conference. Adding and removing a media type to the conference - a member may want to start a power point presentation during a conference. He may want to distribute this new media to all the members. The member will request from the focus to start the new media channel and to allow him to send data in the new channel. Audio only participants - In a multimedia conference some of the Even & Ismail Expires December 21, 2003 [Page 6] Internet-Draft Conference Scenarios June 2003 users who wants to join has no way to send and receive all the media. Typically they can send and receive audio. Such participants will join the conference as audio only participants. The general case is that users may send and receive only part of the media streams available in the multi media conference. Passive participants - In a conference some participants may be listeners to all or part of the media streams. They may be invisible to all the other participants. Recorders - A recorder can be added to the conference. A recorder can record all streams or a subset of the streams. A recorder is a case of a passive participant. 4. Scenarios for media policy control On going conferences media streams may be controlled by authorized users using either a media control protocol or a third party application. This section will describe some typical media control scenarios. The conference can be of any size starting from small conferences (3-5 participants) through medium size of up to 16 participants and large conferences. Some of the media control scenarios are typical to specific conference size. As a general rule larger conferences scenarios tend to be more centrally managed or structured. The scenarios apply to audio conferences as well as to multimedia conferences. There are some specific information about the mixed video layout discussed bellow. 4.1 Video mixing scenarios For video the user selects one of a set of pre-defined video presentations offered by the server. Each video presentation is identified by a textual description as well as an image specifying how the presentation looks like on the screen. In this scenario by choosing a video presentation the user chooses how many video streams (participants) will be viewed at once and the layout of these video streams on the screen. The contents of each sub-window can be defined by a conference policy or controlled by authorized participants. In other aspects like number of different mixes in the conference and a custom mix for each user, these functionality are similar to audio mixing and are based on server capabilities and authorization. Note that for non-centralized mixing if the endpoint mixer does not support the media presentation of the conference, the participant can Even & Ismail Expires December 21, 2003 [Page 7] Internet-Draft Conference Scenarios June 2003 get the default media presentation offered by the endpoint mixer. The following are a list of typical video presentations; there are other layouts available today in commercial products: - Single view: This presentation typically shows the video of the loudest speaker - Dual View: This presentation shows two streams. If the streams are to be multiplexed in one image (typical of centralized servers) the multiplexing can be: 1. Side by side with no altered aspect ratio and hence blanking of parts of the image might be necessary if the streams are to be combined as one image. 2. Side by side windows with altered aspect ratios and hence blanking parts of the image is not necessary. The mixer handles the cropping of the images. 3. One above the other windows with no altered aspect ratio 4. One above the other windows with altered aspect ratio - Quadrate view: This presentation shows 4 streams. If the streams are to be multiplexed into one image (centralized server) they will be arranged in a 2x2 style. Note that in this style the aspect ratios are maintained. - 9 sub-picture view: This presentation shows 9 streams. If the streams are to be multiplexed in one image they will be arranged in a 3x3 style. In the multiplexing case cropping is performed under the discretion of the mixer. - 16 sub-picture view: This presentation shows 16 streams. If the streams are to be multiplexed into one image they will be arranged in a 4x4 style. In this style the aspect ratios are maintained and no cropping or blanking is needed. - 5+1 sub-picture view: This presentation shows 6 streams. If the streams are to be multiplexed into one image then the pictures are laid so that one sub-window occupies four ninth of the screen while the other five occupy a ninth of the screen each. 4.2 Typical video conferencing scenario In this scenario the audio is typically an n-1 audio mixing. Every participant will get a mixed audio of N loudest participants but his Even & Ismail Expires December 21, 2003 [Page 8] Internet-Draft Conference Scenarios June 2003 own audio will not be part of the received mix. All the participants will see the current speaker and he will see the previous speaker. This mode is typical to small conference. User with correct authorization can exclude one or more users from the audio or video mix. An indication might be displayed to the affected users indicating that they are not being seen/heard. User with correct authorization can manipulate the gain level associated with one or more audio streams in the mix. 4.3 Conference Sidebar scenario An authorized user creates a side bar. The user selects whether the sidebar should include the media from the main conference or not and the audio gain level associated with the main conference audio. User invites participants to the sidebar and upon acceptance they start receiving the sidebar media as specified by the sidebar creator. If the new participant is not a member of the conference but rather just the sidebar the participant will only receive the sidebar media without the media of the main conference being mixed. User with the right authorization can move another participant into the sidebar with no indication in which case the user will suddenly start receiving the sidebar media. Sidebar participants with the right authorization can select to hear or not hear the main conference audio mixed with the sidebar audio A participant can be a participant to more than one sidebar but can only actively participate in one. A participant can jump back and forth between the main conference and one or more sidebars to actively participate. 4.4 Coaching scenario This is a call center or a remote training session where there is a supervisor that can monitor. There are the supervised users that may be the call center operators or the teachers The supervisor will be a hidden participant and will not be part of the participant roster. The supervised users might get an announcement/tone indicating that the supervisor has joined. The other participants do not hear the announcement. Even & Ismail Expires December 21, 2003 [Page 9] Internet-Draft Conference Scenarios June 2003 Supervisor listens/sees to the session but can only be heard/seen by the supervised user. Supervisor can become a normal participant in which case the participants will see the supervisor as part of the roster and will start hearing and seeing him. 4.5 Presentation and QA session An example is a panel earning call scenario in which a group of presenters deliver material to a group of people. After the presentation is finished a QA session is opened. The conference is created as a panel and the panel members are identified. Only their streams will be mixed. After the end of the presentation the session chair changes the conference type to normal and now streams from all users may be mixed. A floor control protocol can be used instead of changing the conference type. The chair can grant the right to speak by adding just the participant whose turn is to ask a question to the conference mix. 5. Security Considerations No specific security considerations for this draft. Security consideration will be available in the relevant drafts that will compose the suggested solution References [1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [2] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002. Even & Ismail Expires December 21, 2003 [Page 10] Internet-Draft Conference Scenarios June 2003 Authors' Addresses Roni Even Polycom 94 Derech Em Hamoshavot Petach Tikva 49130 Israel EMail: roni.even@polycom.co.il Nermeen Ismail Cisco Systems, Inc. 170 West Tasman Drive San Jose 95134 CA USA EMail: nismail@cisco.com Even & Ismail Expires December 21, 2003 [Page 11] Internet-Draft Conference Scenarios June 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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