sip for ip communications

www.dynamicsoft.comFall VoN 2000SIP for IP Communications

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?


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


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


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


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


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


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


Session Initiation and Presence/IM Share Requirements cont.

Security Privacy Access controls Authentication

Carriage of MIME Data

Extensibility


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


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


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


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


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


Advantages of Using SIP for Presence and IM Unifies Major Communications Services

Voice/video IM Presence

Shared Databases

Shared Proxies

Shared Servers


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


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


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


Information Resource Jonathan Rosenberg

[email protected] +1 973.952.5000

sip for ip communications

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