1. SIP Conferencing Requirements
Henning Schulzrinne
Petri Koskelainen
Columbia University
18 September 2018
SIP/SIPPING Interim Meeting

2. SIP/SIPPING Interim Meeting
General philosophy
SIP philosophy: strictly separate media and session signaling
thus, media control (e.g., retransmission requests) out of scope
thus, encoding profiles out of scope
orthogonal  apply also to other conference types
Support central-controller conferences:
central mixing or selection/replication or end-system mix
possibly different addresses for different media sessions
media session(s) identified by single SIP URI
SSM: sources send to controller = root of multicast tree
Allow re-use of SIMPLE approaches
subscription permission  conference join permission
buddy list  pre-stored participant list
18 September 2018
SIP/SIPPING Interim Meeting

3. Don't invent new pieces (unless we have to)
Tease out conferencing-specific needs
modular, no H.323-like vertical stack
avoid conferencing-specific profiles
no T.120 special case (except through gateways)
No need to define requirements for things that we already have:
conference creation (but may need termination)
conference joining and leaving
participant muting
renegotiation of leg codecs
18 September 2018
SIP/SIPPING Interim Meeting

4. SIP/SIPPING Interim Meeting
No meta application
Believe that meta-app model is misguided  seems to call for another signaling protocol, identifier, etc.
if no protocol or identifier, invisible
don't want uninstantiated relationships
we can set up sessions (including T ) via SIP
18 September 2018
SIP/SIPPING Interim Meeting

5. SIP/SIPPING Interim Meeting
General model
Divide into requests and notifications
requests = do something
notification = something happened
Requests may trigger notifications if action may be delayed or partial
human approval
group invite
18 September 2018
SIP/SIPPING Interim Meeting

6. Motherhood and Apple Pie
Simplicity
bandwidth-frugal (mobile)
incremental notifications and command
selectable notification granularity
templates for privileges
18 September 2018
SIP/SIPPING Interim Meeting

7. SIP/SIPPING Interim Meeting
Components
Identified by object manipulated:
conferences  conference management
participants within conferences  user management
shared resource  floor control
18 September 2018
SIP/SIPPING Interim Meeting

8. Conference management
Create conference [?]
Delete conference
name vs. resources
Conference properties:
description (subject)
visibility to searching and directories
policies?
18 September 2018
SIP/SIPPING Interim Meeting

9. SIP/SIPPING Interim Meeting
User management
Cause server to invite user(s)
Expel users
List of pre-approved attendees
User rights
invite, expel, approve others
manage & request floor
add media sessions
Join notification
with thresholding
Obtain list of members
18 September 2018
SIP/SIPPING Interim Meeting

10. SIP/SIPPING Interim Meeting
Open issues
Separate conference name existence from resource allocation
want to keep name, but not mixing and bandwidth resources
Template management:
user lists
privilege levels ("chair", "secretary", "panelist", "audience")
18 September 2018
SIP/SIPPING Interim Meeting