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SIP for IP Communications. Jonathan Rosenberg Chief Scientist. IP Communications. “Communications” consists of more than just voice video IM presence wireless Presence and IM are of particular interest Question for discussion: What is SIP’s role in presence and IM?. - PowerPoint PPT Presentation
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www.dynamicsoft.comFall VoN 2000SIP for IP Communications
SIP for IP Communications
Jonathan Rosenberg
Chief Scientist
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
IP Communications
“Communications” consists of more than just voice video IM presence wireless
Presence and IM are of particular interest
Question for discussion: What is SIP’s role in presence and IM?
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Presence Today Also Known as Buddy Lists
Indicates Online/Offline Status
Used Largely to Enable IM
Users Subscribe to “Friends” List
When User is Online Click to send instant message Initiate voice chat (newer)
When Friends Log On/Off, Notifications are Sent
User Status Can Sometimes Be Indicated Busy, not at my desk
Subscriber
Subscriber
Subscriber
Publisher
Notify
Subscribe
Publish
Presence Server
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Presence Today cont. No Standard for IM or Presence
Many Players (i.e., AOL, Yahoo and Tribal Voice)
Each with its own, non-interoperable system
User’s Experience is Limited Metcalfe’s Law Running many different applications
IETF IMPP Group Tasked to Develop a Standard Solution
Proposals Solicited for a Complete Solution at April 2000 Meeting
A SIP Solution was Submitted Co-authors from dynamicsoft, Microsoft, Cisco and Columbia University
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Components of a Presence Solution Subscription
Definition: to subscribe to some entity Requires massive scalability
Distributed subscription state Lightweight transactions
Authentication of subscribers Ability to convey complex subscription rules Routing and namespace partitioning
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Components of a Presence Solution cont. Publication
Enables a user to send information to server for distribution Must be possible to have multiple entities publish for a single address
My cell phone My IM client
Describes communications means, state, capabilities and characteristics
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Components of a Presence Solution cont. Notification
Rapid delivery of published data to subscribers Makes use of distributed subscription state Highly scalable
Presence data changes often Many subscribers
Must be able to convey a variety of presence data formats
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Session Initiation and Presence/IM Share Requirements Network Awareness of Presence State
SIP for call routing Presence for distribution to subscribers
Real-Time Delivery
Forwarding to Server Responsible for a Specific User
Scalability
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Session Initiation and Presence/IM Share Requirements cont.
Security Privacy Access controls Authentication
Carriage of MIME Data
Extensibility
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
SIP Already Provides Publication Capability REGISTER is a Publication Message
for Locations
Allows for SIP and Other URL Types
Multiple Entities Can Publish for the Same Address
SIP Caller Preferences Extension Allows for Attributes for Locations Mobile, landline Home, business Preferences Audio,video - MIME capability
Registrar
Client
Client
Client
Registrar
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
SIP Extension for Presence New Entity: Presence Agent
Purely logical entity Knows presence state of user Receives SUBSCRIBE requests Generates NOTIFY requests Co-located with proxy/registrar or User Agent
Basic Operation Subscriber send SUBSCRIBE Routed to PA using normal SIP PA authorizes subscriber Acceptance contains presence state NOTIFY sent when state changes
Routed using SIP Record-Route
REGISTER
SUBSCRIBE
NOTIFY
Presence Agent +Proxy/Registrar = Presence Server
Proxy
Subscriber
Presentity
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Features of SIP For Presence Extension End Users Can Perform Notifications
Scalability
Presence Agent Function Can Migrate Network provides service when user is offline When user is online, subscriptions migrate to user
Offline Subscriptions Handled
Presence server always asks user if a subscription should be accepted
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Features of SIP For Presence Extension cont. Multiple Entities Can Generate Presence Information for One
Presentity Mobile phone, PDA, laptop and desktop PC
Multiple Presence Clients Can Be Online at Once
Traditional SIP Proxies Route SUBSCRIBE and NOTIFY
Presence Data is Orthogonal
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
SIP Extension for Instant Messaging Operation of Extension
Messages carried in SIP messages New method - MESSAGE Routed to recipient using normal SIP techniques Simple extension
Features Associates an IM with an existing call Any MIME data can be sent TCP for large messages Routed by existing proxies and registrars Possible to have a different client for IM and communications
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Advantages of Using SIP for Presence and IM Unifies Major Communications Services
Voice/video IM Presence
Shared Databases
Shared Proxies
Shared Servers
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Advantages of Using SIP For Presence and IM Reduces Management Costs
One infrastructure instead of two One NOC instead of two One set of managers instead of two
Enables New Combined Services Combined services integrate voice, video, IM, presence, web amd email These new services will be a “killer app” for communications on
the Internet Delivery of combined services is greatly simplified by alignment of
presence and communication signaling protocols
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
New Service Example: Traffic Jam Alerts Uses Geographic Locale as
Presence Component Mobile phone site location GPS
Service Definition Turn on mobile phone in car As you drive, application server
monitors location As you approach traffic, service
will call you Voice response system reads
out alternate route
NOTIFY
INVITE
REGISTER
Application Server
Presence Server
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
New Service Example: Auto Conference Calls
Problem: Difficult to juggle busy people’s schedules to set up audio conference calls
Solution: use presence to set up the call when everyone is available
Procedure: Enter email addresses into a web
form (1) Application subscribes to users (2) When all are online, application
calls each participant, calls a conference bridge, connects them together
Presence
HTTPSIP Calls
AS
Conference Server
PresenceServer
www.dynamicsoft.comFall VoN 2000SIP for IP Communications
Information Resource Jonathan Rosenberg
[email protected] +1 973.952.5000