Larry AmiotNorthwestern [email protected]
Internet2 Commons Site Coordinator TrainingSeptember 27, 2004Austin, Texas
Introduction to SIP
2
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
3
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
4
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
5
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
6
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
8
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
11
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
12
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
13
Windows Messenger- The Microsoft Approach
14
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
15
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
20
Wave3’s Sessions SIP Client
21
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
24
A Few SIP Clients
Microsoft Windows MessengereCONF (Radvision resale)Wave3 Sessions (www.wave3software.com)
Network Convergence Laboratory at Claremont Graduate University (ncl.cug.edu)
25
A Few SIP Proxy ServersMicrosoft Live Communications ServerHCL Technologies (www.hcltech.com) IndigoUbiquitySNOMVOCAL IptelDynamicSoftSiemensNorteleCONF
26
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