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Introduction to SIP
Larry Amiot
Northwestern University
[email protected]
Internet2 Commons Site Coordinator Training
March 22, 2004
Indianapolis, Indiana
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)
Authentication
Office integration
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SIP Entities
User Agent
• User Agent Client (UAC)
• User Agent Server (UAS)
Redirect Server
Proxy Server
Registrar
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Application
SIP Session Establishment and Call Termination
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Figure courtesy of Radvision Ltd
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
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Call Redirection Using a Redirect Server
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Figure courtesy of Radvision Ltd
Call Proxy Scenario
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Figure courtesy of Radvision Ltd
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 used
Microsoft LCS supports Kerberos and NTLM
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A Few SIP Implementation
Examples
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
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SIP Point-to-Point Interoperability Using the Microsoft LCS
Microsoft Live
Communication
Server
Microsoft
Active
Directory
Internet
Windows Messenger
Clients
SIP/H.323 Interoperability Using the Radvision MCU
Radvision
MCU
H.323
Microsoft Live
Communication
Server
S
I
P
Internet
H.323 Clients
Microsoft
Active
Directory
Windows Messenger
Clients
SIP/H.323 Interoperability Using the Radvision MCU
Radvision
MCU
H.323
S
I IMfirst
P
Internet
H.323 Clients
Microsoft Live
Communication
Server
Microsoft
Active
Directory
Windows Messenger
Clients
SIP/H.323 Interoperability Using the Radvision MCU
UAS
Radvision
MCU
H.323
S
I
P
eCONF SIP
Clients
Internet
H.323 Clients
UAC
Wave3’s Session SIP Client
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Session
 Sip-based
 Works on/between PCs and Macs
 IM, Audio/video, & data sharing
 Can go point-to-point using IP addressing
 Can work with a SIP server
 Wave3 has a server for multipoint video
 Released version (WAVELETS codec) not compatible with
• H.323
• Windows Messenger
• Working on new H.261/H.263 video encoder for
compatibility
 Not compatible with Windows Messenger data sharing
 No echo cancellation
 No presence yet
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SIP/H.323 Interoperability Using the Radvision MCU
Radvision
MCU
H.323
Your Favorite
SIP Server
S
I
P
Internet
H.323 Clients
Session Clients
A Few SIP Clients
Microsoft Windows Messenger
eCONF (Radvision resale?)
Wave3 Session
(www.wave3software.com)
Network Convergence Laboratory at
Claremont Graduate University
(ncl.cgu.edu)
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A Few SIP Proxy Servers
 Microsoft Live Communications Server
 HCL Technologies (www.hcltech.com)
 Indigo
 Ubiquity
 SNOM
 VOCAL
 Iptel
 DynamicSoft
 Siemens
 Nortel
 eCONF
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Summary
SIP is an emerging Technology
Staying with single a vender solution is
currently workable
Interoperability between vender products is
still in early stages
Multipoint conferencing is possible
Data Sharing is still an interoperability
problem
Selection of a SIP Proxy Server is critical as is
its method of authentication
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