Larry AmiotNorthwestern Universityamiot@northwestern.edu

Internet2 Commons Site Coordinator TrainingSeptember 27, 2004Austin, Texas

Introduction to SIP

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How Do We Communicate?

Telephone (home, work, & cell phone) Email Text messaging Data sharing (PowerPoint, applications,

white board, desktop, etc.) Audio/video File transfer Ink- tablet PC

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Questions?

…but how do we know where to find the person we want to communicate with

...and given the availability of my resources, which of the persons devices do I want to communicate with

..and what is the address of that device ..and how does the person control his

active/inactive devices ..and how do we authenticate people ..and how do we bridge this between

organizations

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Enter the Session Initiation Protocol (SIP)

An emerging signaling protocol for: • Initiating,• Managing, and • Terminating messaging, voice, and video sessions

Internet Engineering Task Force (IETF)• Developed by the SIP Working Group• Published as IETF RFC 3261

Connectivity using IP May be extended for services such as:

• call control services, • mobility,• interoperability with telephony systems, and more

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SIP and its Extensions

Presence• The willingness and ability of a user and their devices to communicate with other users on the network

• SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE)

AuthenticationOffice integration

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SIP Entities

User Agent• User Agent Client (UAC)• User Agent Server (UAS)

Redirect ServerProxy Server Registrar

7SIP Session Establishment and Call Termination

Figure courtesy of Radvision Ltd

Application

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Session Description Protocol (SDP)

SDP is the protocol used to describe multimedia session announcement, multimedia session invitation and other forms of multimedia session initiation.

A multimedia session is defined, for these purposes, as a set of media streams that exist for a duration of time.

RFP 2327

9Figure courtesy of Radvision Ltd

Call Redirection Using a Redirect Server

10Figure courtesy of Radvision Ltd

Call Proxy Scenario

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Authentication- RFC 3261

Any time that a proxy server or UA receives a request, it MAY challenge the initiator of the request to provide assurance of its identity.

No authorization systems are recommended or discussed in this document.

The "Digest" authentication mechanism described in this section provides message authentication and replay protection only, without message integrity or confidentiality.

Basic should not be usedMicrosoft LCS supports Kerberos and NTLM

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A Few Multipoint SIP Implementation Examples

There is considerable point-to-point SIP-based videoconferencing going on

The following examples concentrate on multipoint videoconferencing

• Microsoft Live Communications Server• Wave3 Sessions• Radvision ViaIP

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Windows Messenger- The Microsoft Approach

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Windows Messenger

SIP-based Runs on Windows XP systems (sorry no

Macs) Core Features:

– Presence and contact list management– Instant Messaging– Voice and Video– Data collaboration and File transfer– PC to Phone– Administrative Policies to enable/disable features– Acoustic Echo Cancellation in software

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Windows Messenger

Microsoft .Net SIP server or enterprise SIP server

Can not go point-to-point using IP addressing- needs proxy server

Microsoft Live Communications Server (LCS) is their proxy server

Internet

Windows Messenger Clients

Microsoft Live Communication

Server

SIP Point-to-Point Interoperability Using the Microsoft LCS

Microsoft Active Directory

Radvision MCU

SIP

H.323

Internet

H.323 ClientsWindows Messenger

Clients

Microsoft Live Communication

Server

SIP/H.323 Interoperability Using the Radvision MCU

Microsoft Active Directory

Radvision MCU

SIP

H.323

Internet

H.323 ClientsWindows Messenger

Clients

Microsoft Live Communication

Server

SIP/H.323 Interoperability Using the Radvision MCU

IMfirst

Microsoft Active Directory

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Wave3’s Sessions SIP Client

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SessionsSip-basedWorks on/between PCs and

MACs IM, Audio/video, & data

sharingPoint-to-point using IP

addressing, or work with a SIP server

Wave3 has a server for multipoint video

WAVELETS codec Not compatible with

Windows Messenger data sharing

No echo cancellation

Session 3.0 beta• h.261 cif/qcif• h.263 cif/qcif• additional audio codecs

• Presence• IM• DTMF• Symmetric signaling and symmetric RTP to support NAT traversal solutions.

Radvision MCU

SIP

H.323

Internet

H.323 ClientsSession Clients

Your Favorite SIP Server

SIP/H.323 Interoperability Using the Radvision MCU

Radvision MCU

SIP

H.323

Internet

H.323 ClientsWave3 Session Clients

IPtel SIP Server

SIP Evaluation at Northwestern University

H.350 LDAP Server

Authentication

Not yet working

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A Few SIP Clients

Microsoft Windows MessengereCONF (Radvision resale)Wave3 Sessions (www.wave3software.com)

Network Convergence Laboratory at Claremont Graduate University (ncl.cug.edu)

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A Few SIP Proxy ServersMicrosoft Live Communications ServerHCL Technologies (www.hcltech.com) IndigoUbiquitySNOMVOCAL IptelDynamicSoftSiemensNorteleCONF

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Summary

SIP is an emerging TechnologyStaying with single a vender solution is currently workable

Interoperability between vender products is still in early stages

Multipoint conferencing is possibleData Sharing is still an interoperability problem

Selection of a SIP Proxy Server is critical as is its method of authentication