Office Communications Server 2007 Videoconferencing Interoperability

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Office Communications Server

2007 Videoconferencing

Interoperability

Microsoft Corporation Published: July 31, 2008

Executive Summary

Microsoft® Office Communications Server 2007 is the first Microsoft product to combine enterprise-ready IM (instant messaging), presence, videoconferencing, Web conferencing, and VoIP (Voice over IP) telephony in one solution. In addition, Office Communications Server 2007 includes real-time videoconferencing solutions running on servers in your intranet or interoperating with videoconferencing hardware vendors (such as TANDBERG or Polycom).

Providing interoperability between Office Communications Server 2007 and videoconferencing vendors allows you to take advantage of your existing videoconferencing hardware investment while extending videoconferencing features to other users with minimal hardware investment and user training. The users that attend conferences using dedicated videoconferencing hardware can schedule meetings and determine attendee availability using familiar tools, such as Microsoft Office Outlook® or Microsoft Office

Communicator 2007. This paper discusses:

• An overview of videoconferencing, including benefits, features, and industry standards used in videoconferencing solutions.

• Features and capabilities of Office Communications Server 2007 that are utilized in videoconferencing solutions.

• Interoperability of Office Communications Server 2007 with existing videoconferencing vendor solutions.

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This is a preliminary document and may be changed substantially prior to final commercial release of the software described herein.

The information contained in this document represents the current view of Microsoft Corporation on the issues discussed as of the date of publication. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information presented after the date of publication.

This White Paper is for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS DOCUMENT.

Complying with all applicable copyright laws is the responsibility of the user. Without limiting the rights under copyright, no part of this document may be reproduced, stored in or introduced into a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise), or for any purpose, without the express written permission of Microsoft Corporation.

Microsoft may have patents, patent applications, trademarks, copyrights, or other intellectual property rights covering subject matter in this document. Except as expressly provided in any written license agreement from Microsoft, the furnishing of this document does not give you any license to these patents, trademarks, copyrights, or other intellectual property.

Unless otherwise noted, the companies, organizations, products, domain names, e-mail addresses, logos, people, places, and events depicted in examples herein are fictitious. No association with any real company, organization, product, domain name, e-mail address, logo, person, place, or event is intended or should be inferred.

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Introduction

Microsoft® Office Communications Server 2007 provides solutions for real-time communications within your organization, between federated networks, and with users on the Internet. The solutions include instant messaging, real-time audio communications, real-time videoconferencing, Web conferencing, and playback of recorded video conferences.

Using This White Paper

This white paper focuses on the interoperability of Office Communications Server 2007 with real-time videoconferencing vendors. This paper discusses the following topics:

• Creating videoconferencing solutions using Office Communications Server 2007. • Creating videoconferencing solutions that interoperate Office Communications Server

2007 and videoconferencing hardware vendors.

• How Microsoft envisions future interoperability with videoconferencing vendors.

As you read this white paper, identify the videoconferencing features that are needed in your organization and select the videoconferencing solutions that best address your organization’s needs.

Videoconferencing Concepts

Videoconferencing is part of a $4-5 billion dollar real-time collaboration technology sector that includes audio, video, and Web conferencing products and services. More and more organizations adopt these products and services each year. Some of these components are not only installed within an organization, but are also available on a “pay-as-you-go” basis by conferencing service providers.

Although the implementation for each videoconferencing hardware and software vendor may differ, the following are some of the common components found in most videoconferencing solutions:

• Group videoconferencing endpoints. These devices are videoconferencing clients that are designed to be used in shared environments such as meeting rooms, boardrooms, and auditoriums. These devices are sometimes referred to as room videoconferencing endpoints or systems.

• Individual videoconferencing endpoints. These devices are videoconferencing clients that are designed to be used for personal or single-person use. Examples of this type of device include videophones, executive systems, and PC-based solutions optimized for the office and cubicle work environment.

• Multipoint control units (MCUs). These devices enable two or more participants to be in a single videoconference. These devices are also known as bridges.

• Videoconferencing gateways. These devices connect users on different networks, typically IP and Integrated Services Digital Network (ISDN) as well as public switched telephone networks (PSTNs)

• NAT-firewall traversal. This technology enables audio and video calls to connect across different networks and user domains. You can use them to connect your videoconferencing infrastructure with federated networks or users who access your infrastructure from the Internet. A federated network is a network that is owned and managed by two organizations for the purpose of sharing networking resources and information.

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between endpoints as well as between endpoints and other infrastructure components (such as MCUs and gateways).

The following figure illustrates the role of gatekeepers in establishing connections between videoconferencing endpoints.

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Interoperability in modern videoconferencing solutions is facilitated by industry standards and protocols, including:

• H.323. This is an umbrella standard that defines the protocols used to provide audio-visual communications sessions. This standard is widely implemented by voice and videoconferencing equipment manufacturers and deployed by service providers and enterprises for both voice and video services over IP-based networks. The following figure illustrates the other standards and protocols that are encompassed in the H.323 umbrella standard. For more information about the H.323 standard, see H.323: Packet-based multimedia communications systems at

www.itu.int/rec/T-REC-H.323/e.

Figure 2. H.323 umbrella standard and the relationship with other standards and protocols

• H.239. Typically, videoconferences have an audio channel, a video channel, and optionally a data channel. The video channel usually shows the participants. The H.239 standard defines how to establish additional video channels, which can be used for additional video sources such as a computer display or an additional camera. The H.239 standard does this by labeling video channels with a role and then the role labels are used by H.320 and H.323–based systems. In multipoint conferencing, the H.239 standard defines token procedures to guarantee that only one endpoint in the conference sends the additional video channel, which is then distributed to all conference participants. For more information about the H.239 standard, see H.239: Role management and additional media channels for H.300-series terminals at www.itu.int/rec/T-REC-H.239/en.

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• Centralized Conferencing Control Protocol (C3P). A custom protocol for communicating conference creation and control commands from clients to Office Communications Server 2007. C3P commands are carried as XML in SIP SERVICE or INFO messages. C3P commands are carried over HTTPS to all conferencing servers. For more information about the C3P standard, see Centralized Conferencing Control Protocol at http://tools.ietf.org/html/draft-levin-xcon-cccp-04.

• Session Initiation Protocol (SIP). The industry standard protocol described in IETF RFC 3261 that defines a standard for session setup, termination, and media

negotiation between two parties. It is widely used for Voice-over-IP (VoIP) and video call signaling in IP networks. SIP is an alternative to H.323 for VoIP and video call signaling.

• Computer Supported Telecommunications Application (CSTA). This standard is an abstraction layer for telecommunication applications that is independent of the underlying signaling protocols and devices. The core of this standard is the definition of call control features, such as call answering, call forwarding, bridging calls, and call hold. For more information about CSTA, see Computer Supported

Telecommunications Applications (CSTA) at

www.ecma-international.org/activities/Communications/TG11/cstaIII.htm.

• Persistent Shared Object Model (PSOM). A proprietary protocol for the transport of real-time data, including audio and video. PSOM uses TCP or TLS as the underlying transport.

• Secure Real-time Transport Protocol (SRTP). An IETF standard protocol that is used in Office Communications Server 2007 to securely transport audio and video content to various media devices. It is based on the RTP that defines a packet format for carrying audio and video over IP networks.

• RTCP (Real-Time Control Protocol). An IETF standard protocol used in conjunction with RTP and SRTP to convey information about the signal quality of an

audio/videoconferencing session to various media devices.

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Figure 3. Protocol interaction between Office Communications Server 2007 and client computers running Office Communicator 2007

Overview of Office Communications Server 2007

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Videoconferencing Architecture in Office Communications Server 2007

The architecture of Office Communications Server 2007 allows for deployment in a number of different configurations, based on the business, scaling, and availability requirements of an organization. This document focuses on the “Enterprise Edition: Consolidated Configuration” scenario as described in the Office Communications Server 2007 Document: Technical Overview.

For more information about this and other scenarios, see:

• Office Communications Server 2007 Document: Technical Overview at

www.microsoft.com/downloads/details.aspx?FamilyID=09b218ea-6ff6-4679-a117-9767ab98990a&DisplayLang=en.

• Office Communications Server 2007 Document: Planning Guide at

www.microsoft.com/downloads/details.aspx?familyid=723347C6-FA1F-44D8-A7FA-8974C3B596F4&displaylang=en.

The following figure illustrates a common deployment scenario for Office Communications Server 2007: the “Enterprise Edition: Consolidated Configuration” scenario. This scenario is typically used as the initial deployment for mission-critical large enterprise instant messaging and conference usage.

This scenario assumes one centralized geographic location that provides videoconferencing solutions within that location. The solution includes four server computers running the Office Communications Server 2007 server roles. The “Enterprise Edition: Consolidated Configuration” scenario is a pool configuration in which all server components are collocated on the pool’s front-end servers (with the exception of the back-end database, which must reside on a separate dedicated computer). Consolidated Configuration provides scalability and high availability and yet is easy to plan, deploy, and manage. For more information about this scenario, see the “Enterprise Edition: Consolidated Configuration” and “Perimeter Network Configuration for IM and Conferencing” sections in Office Communications Server 2007 Document: Technical Overview. The following technologies, services, and hardware components are required as prerequisites to deploy this solution:

• Active Directory® running in Windows 2000 native mode or higher functional level in the domain in which the computers running Office Communications Server 2007 are members.

• Microsoft SQL Server® 2004 with Service Pack 4, SQL Server 2005 Service Pack 1, or a later version of SQL Server Service Pack that provides database storage for the Enterprise Pool.

• Public key infrastructure (PKI) to provide certificates used in mutual server computer authentication and external client authentication.

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The following table lists the core Office Communications Server 2007 components used in this scenario.

Table 1. Office Communications Server 2007 components used in scenario

Component Description

Focus The Focus is the conference state server. It is implemented as a SIP user agent that is addressable by using a conference URI. The Focus runs in the User Services module of all front-end servers. All group IM, multiparty A/V, and data collaboration sessions are managed on the server by the Focus.

Focus Factory The Focus Factory is the part of the Focus that is responsible for scheduling. When a user creates a new meeting, the meeting client sends a SIP SERVICE message to the Focus Factory, which creates a new instance of the conference in the conference database and returns information about the newly created conference to the client. A separate instance of the Focus exists for each active conference.

Web

Conferencing Server

Manages conference data collaboration, including native support for Microsoft Office PowerPoint® presentations, Microsoft Office document sharing, white boarding, application sharing, polling, Q&A, compliance logging, annotations, meeting

summaries, handouts, and various multimedia formats. The Web Conferencing Server can reside either on the front-end server (Standard Edition and Enterprise Edition Consolidated Pool) or on a separate physical computer (Enterprise Edition Expanded Pool).The Web Conferencing Server uses PSOM, a Microsoft Office Live Meeting protocol, for uploading slides to a meeting.

A/V

Conferencing Edge Server

Provides multiparty IP audio and video mixing and relaying, including Microsoft RoundTable™, by using industry standard RTP and RTCP. The A/V Conferencing Edge Server can reside either on the front-end server (Standard Edition and

Enterprise Edition Consolidated Pool) or on a separate physical computer (Enterprise Edition Expanded Pool).

IM

Conferencing Server

Enables group IM by relaying IM traffic among all participants. When a third participant is added to a peer-to-peer IM conversation, the initiating client invites the IM Conferencing Server to the conversation. From that point, all messages among the participants are routed through the IM Conferencing Server. The IM Conferencing Server is an integral part of the front-end server and cannot be installed on a separate computer.

Telephony Conferencing Server

Responsible for ACP (audio conferencing provider) integration. Supports both dial-out and dial-in, as well as standard third-party call control features such as mute and eject. The Telephony Conferencing Server does not support mixing VoIP and PSTN in the same call. To connect dial-out to PSTN endpoints requires a Mediation Server, as described later in this overview. The Telephony Conferencing Server is an integral part of the front-end server and cannot be installed on a separate computer. Conferencing

Server Factory

When the Focus requests a particular conferencing server for a meeting, the Focus sends the request to the Conferencing Server Factory, which determines which conferencing server is available to service the request and returns its URL to the Focus. The Conferencing Server Factory is responsible for provisioning a meeting for a particular media type on a conferencing server by using local policies for creating meetings. A Conferencing Server Factory provisions meetings according to local policies and takes into account the current load on the conferencing servers before assigning one to a meeting.

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The following table lists additional Office Communications Server 2007 components that support external users.

Table 2. Additional Office Communications Server 2007 components that support external users

Access Edge Server

Formerly known as the Access Proxy, the Access Edge Server handles all SIP traffic across the corporate firewall. The Access Edge Server handles only the SIP traffic that is necessary to establish and validate connections. It does not handle data transfer, nor does it authenticate users. Authentication of inbound traffic is performed by the Director or the front-end server. The Access Edge Server is essential for all external user scenarios, including conferencing, remote user access, federation, and public IM connectivity.

Director The Office Communications Server 2007 Director is the recommended internal next-hop server to which an Access Edge Server routes inbound SIP traffic destined to internal servers. The Director authenticates inbound requests and distributes them among the servers in the Enterprise pool or to the appropriate Standard Edition server.

Web

Conferencing Edge Server

The Web Conferencing Edge Server proxies PSOM traffic between the Web

Conferencing Server and external clients. External conference traffic must be authorized by the Web Conferencing Edge Server before it is forwarded to the Web Conferencing Server. The Web Conferencing Edge Server requires that external clients use TLS connections and obtain a conference session key.

A/V Edge Server

The A/V Edge Server provides a single trusted connection point through which inbound and outbound media traffic can securely traverse NATs and firewalls. The industry standard solution for multimedia traversal of firewalls is ICE (Interactive Connectivity Establishment), which is based on the STUN (Simple Traversal Underneath NAT) and TURN (Traversal Using Relay NAT) protocols. The A/V Edge Server is a STUN server. All users are authenticated to secure both access to the enterprise and use of the firewall traversal service that is provided by the A/V Edge Server. To send media inside the enterprise, an external user must be authenticated and must have an authenticated internal user agree to communicate with him or her through the A/V Edge Server. HTTP

Reverse Proxy

Office Communications Server 2007 conferencing support for external users also requires deploying an HTTP reverse proxy in the perimeter network for the purpose of carrying HTTP and HTTPS traffic for external users. The HTTP reverse proxy is used to download the following data for external users:

• Address Book Server files • Web conferencing content

• Expanded distribution lists for group IM

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Office Communications Server 2007 Concepts and Features

You can deploy Office Communications Server 2007 in organizations that support a small number of users or large organizations that have a large number of users. Office Communications Server 2007 is available in the following editions:

• Standard Edition. This edition provides all the features available in Office Communications Server 2007, but runs on a single computer. Standard Edition is typically selected for smaller organizations or in scenarios in which branch offices are isolated from one another.

• Enterprise Edition. This edition provides all the features available in Office Communications Server 2007, but can be run on multiple computers to scale to the desired number or users and to provide fault-tolerance. This edition is typically selected for larger organizations or in scenarios in which branch offices are interconnected with one another. This white paper focuses on deploying the Enterprise Edition.

For more information about Office Communications Server 2007, see Communications Server 2007 Document: Technical Overview at

www.microsoft.com/downloads/details.aspx?familyid=09b218ea-6ff6-4679-a117-9767ab98990a&displaylang=en&tm.

For more information about how Exchange Server Unified Messaging integrates with Office Communications Server 2007, see Exchange Server 2007 Unified Messaging at

www.microsoft.com/exchange/evaluation/unifiedmessaging/umwhitepaper.mspx.

Videoconferencing

Office Communications Server 2007 supports multiparty audiovisual (A/V) conferencing. Users can specify audiovisual when scheduling a conference or can add audio or video to an existing IM conversation or conference call. Managing multiparty audio and video sessions is the job of the A/V Conferencing Server. The A/V Conferencing Server can be collocated with the pool front-end server or deployed in the pool on a separate computer for greater scalability. When deployed on a separate computer, the A/V Conferencing Server can support up to 250 participants within a single session and up to 1,250 total participants per A/V Conferencing Server.

Office Communications Server 2007 also extends audiovisual conferencing to external users. The A/V Edge Server acts as a media relay for the transmission of both audio and video signals across corporate firewalls. This makes it possible to share audio and video with external users. The A/V Edge Server can be collocated with the Access Edge Server or installed on a separate computer in the perimeter network.

Office Communicator clients support peer-to-peer audiovisual communication for users both inside and outside the organization’s firewall.

Office Communications Server 2007 supports the RoundTable communications system, which is an A/V conference-room device from Microsoft that provides a 360-degree surround video and audio experience. Attending a video conference that uses RoundTable is similar to attending a meeting in person. The audio and video of the entire conference room is delivered to other videoconferencing attendees in real time.

Audio Conferencing

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ACP integration is managed by the Telephony Conferencing Server, which always runs as a separate process on either a Standard Edition server or Enterprise Edition front-end server. Integration with the Audio Conferencing Provider occurs by configuring a federated connection with the external service provider, as you would with any other federated partner.

Interoperability with Partners

Office Communications Server 2007 has an extensible architecture that allows partners to develop software features and dedicated hardware that interoperates with Office Communications Server 2007. This

architecture supports the interoperability of:

• Dedicated audio conferencing devices. These partners provide dedicated hardware devices that can participate in VoIP voice conferences with Office Communicator 2007 clients.

• Dedicated videoconferencing devices. These partners provided dedicated hardware devices that can participate in videoconferences with Office Communicator 2007 clients. Interoperating with these vendors is the focus of this white paper. • H.323 videoconferencing devices. These partners provide gateway services that

allow H.323-based (and in some cases H.320-based) devices to participate in videoconferences with Office Communicator 2007 clients or other native endpoints.

Office Communications Server 2007 Interoperability with

Videoconferencing Vendor Solutions

The current interoperability between Office Communications Server 2007 and videoconferencing vendors is accomplished by each vendor. An example of this interoperability is the videoconferencing solutions provided by TANDBERG and Polycom.

Office Communications Server 2007 Interoperability with TANDBERG

Solutions

TANDBERG, a global visual communications company, provides videoconferencing products and services in more than 90 countries worldwide. If an organization has an existing TANDBERG videoconferencing solution, they can interoperate with Office Communications Server 2007 with minimal effort.

Note: Although TANDBERG is used an example in this white paper, similar solutions exist for other

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Overview of TANDBERG-based Solutions

The following figure illustrates a typical TANDBERG-based videoconferencing solution.

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The following table lists the components that are included in the solution illustrated in Figure 5.

Table 3. Components in a TANDBERG-based videoconferencing solution

TANDBERG MXP Endpoints

These components are a family of dedicated standards-based videoconferencing hardware endpoints (clients) that support SIP and H.323 and can be used with other TANDBERG products as well as other standards-based videoconferencing products. They range from complete Telepresence systems to high definition personal

appliances for the executive desktop. TANDBERG Video Communication Server (VCS) Control and TANDBERG VCS Expressway

These components bridge the gap between SIP and H.323 and deliver three unique applications in one centralized device. These components provide video call forwarding capabilities, support both SIP and H.323, and facilitate the migration to SIP.

The TANDBERG VCS Control is the TANDBERG implementation of the gatekeeper functionality within the TANDBERG solution. The TANDBERG VCS Expressway is the TANDBERG implementation of the border controller function that provides network access translation (NAT) and firewall traversal.

TANDBERG Codian MCU 4500

This component connects multiple audio and video sites in one or more ISDN, IP and mixed ISDN and IP videoconferences (including H.323 and SIP-based endpoints).

Interoperability with Office Communications Server 2007

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Figure 6. Interoperability of Office Communications Server 2007 in a TANDBERG-based solution

To provide videoconferencing interoperability between Office Communicator 2007 clients and clients in the TANDBERG infrastructure, the following happens:

1. Office Communicator 2007 clients register their presence status with the pool of servers running

Office Communications Server 2007. In this configuration, the Office Communicator 2007 clients

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2. TANDBERG endpoints register their presence status with the TANDBERG VCS and the pools of

servers running Office Communications Server 2007. Current versions of TANDBERG endpoints

have the ability to register directly with Office Communications Server by using SIP. To provide interoperability with H.323 clients and other legacy endpoints, these endpoints also register with the TANDBERG VCS. The TANDBERG VCS functions as a SIP proxy, H.323 gateway, and H.323 gatekeeper.

3. Legacy endpoints register their presence status with the TANDBERG VCS. These endpoints must register with the TANDBERG VCS to participate in videoconferences with Office Communicator 2007 clients and current TANDBERG endpoints. The endpoints appear as H.323 clients to the TANDBERG VCS.

4. TANDBERG Codian MCU 4500 registers the presence of virtual conference rooms with Office

Communications Server 2007. A TANDBERG virtual conference room is a video conference between

two or more individual endpoints. The TANDBERG virtual conference rooms allow multiple point-to-point connections with Office Communicator 2007 clients to conference with other TANDBERG-based endpoints as well as videoconferencing endpoints from other vendors.

The following figure illustrates how the presence status of individual TANDBERG endpoints and virtual conference rooms displays in Office Communicator 2007. From an Office Communicator 2007 perspective, the TANDBERG endpoints and virtual conference rooms appear as other Office Communicator 2007 contacts.

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Videoconferences between these clients are accomplished either as point-to-point calls between Office Communicator clients and the TANDBERG MXP endpoints or as a multiparty conference through the TANDBERG Codian MCU 4500. The TANDBERG Codian MCU 4500 allows Office Communicator 2007 clients to conference with the current TANDBERG endpoints and legacy endpoints (such as H.323 and H.320–based endpoints).

Although the solution in Figure 6 provides a level of interoperability between the Office Communications Server 2007 infrastructure and TANDBERG infrastructure, there are some limitations to the solution. The following table lists some limitations of the current interoperability between Office Communications Server 2007 and TANDBERG-based infrastructure.

Table 4. Limitations of the current interoperability between Office Communications Server 2007 and TANDBERG-based infrastructure

Limitation Description

Office Communicator 2007 endpoints can only perform point-to-point videoconferences with TANDBERG infrastructure

Currently, only point-to-point videoconferences are supported between Office Communicator 2007 endpoints and the TANDBERG infrastructure. However, one of the endpoints in the videoconference could be a TANDBERG virtual conference room, which may in turn have other endpoints connected to the virtual conference room. Only Office Communicator 2007

endpoints within the intranet can participate in videoconferences with TANDBERG endpoints

Currently, Office Communicator 2007 endpoints that are outside the intranet, such as users on federated networks or the Internet, are only able to participate in videoconferences with Office

Communicator 2007 endpoints within the intranet through the A/V Edge Server. In future releases, Office Communicator 2007 endpoints outside the intranet will be able to communicate with TANDBERG endpoints. For more information, see the “How

Microsoft Envisions the Future of Videoconferencing Interoperability” topic later in this paper.

Office Communications Server 2007 Interoperability with Polycom

Solutions

Polycom Inc. is one of the worldwide leaders in unified communication and collaboration solutions. Polycom is one of the earliest partners with Microsoft within the conferencing and collaboration industry. If an organization has an existing Polycom videoconferencing solution, they can interoperate with Office Communications Server 2007 with minimal effort.

Note: Although Polycom is used an example in this white paper, similar solutions exist for other

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Overview of Polycom-based Solutions

The following figure illustrates a typical Polycom-based videoconferencing solution.

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The following table lists the components that are included in the solution illustrated in Figure 8.

Table 5. Components in Polycom-based videoconferencing solution

Polycom endpoints

These components are a family of dedicated videoconferencing hardware endpoints (clients) that can be used with other Polycom products. They range from complete Telepresence systems to high definition personal appliances for the executive desktop.

RMX 2000 This component connects multiple audio and video sites in one or more videoconferences (including H.323 and SIP-based endpoints).

ReadiManager SE200

This component provides a centralized management application device that delivers scheduling, device, and network management and full gatekeeper functionality. Polycom Video

Border Proxy (VBP)

This component extends videoconferencing to remote users without interference from inter-company firewalls. The VBP provides NAT and firewall traversal between trusted intranets. The VBP also provides optimized video quality by prioritizing video traffic over data traffic and providing both shortest path routing and traffic shaping.

Interoperability with Office Communications Server 2007

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Figure 9. Interoperability of Office Communications Server 2007 in a Polycom-based solution

To provide videoconferencing interoperability between Office Communicator 2007 clients and clients in the Polycom infrastructure, the following happens:

1. Office Communicator 2007 clients register their presence status with Office Communications

Server 2007. In this configuration, the Office Communicator 2007 clients perform as they would in a

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2. Polycom HDX video endpoints and CX Series phones register their presence status directly with

Office Communications Server 2007. Current versions of Polycom HDX and CX endpoints have the

ability to register directly with Office Communications Server by using SIP.

3. The Polycom RMX 2000 registers the presence of virtual conference rooms with Office

Communications Server 2007. A Polycom virtual conference room is a videoconference between two

or more individual endpoints. The Polycom virtual conference rooms allow multiple point-to-point connections with Office Communicator 2007 clients to conference with other Polycom-based endpoints as well as videoconferencing endpoints from other vendors.

The following figure illustrates how the presence status of individual Polycom endpoints and virtual

conference rooms displays in Office Communicator 2007. From an Office Communicator 2007 perspective, the Polycom endpoints and virtual meeting rooms appear as other Office Communicator 2007 contacts.

Figure 10. Presence status of Polycom endpoints in Office Communicator 2007

The Polycom RMX 2000 allows Office Communicator 2007 clients to conference with the current Polycom endpoints and legacy endpoints (such as H.323 and PSTN–based endpoints).

Although the solution in Figure 9 provides a level of interoperability between the Office Communications Server 2007 infrastructure and Polycom infrastructure, there are some limitations to the solution. The following table lists some limitations of the current interoperability between Office Communications Server 2007 and Polycom-based infrastructure.

Table 6. Limitations of the current interoperability between Office Communications Server 2007 and Polycom-based infrastructure

Office Communicator 2007 endpoints can only perform point-to-point videoconferences with Polycom infrastructure

Currently, only point-to-point videoconferences are supported between Office Communicator 2007 endpoints and the Polycom

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Only Office Communicator 2007 endpoints within the intranet can participate in videoconferences with Polycom endpoints

Currently, Office Communicator 2007 endpoints that are outside the intranet, such as users on federated networks or the Internet, are only able to participate in videoconferences with Office Communicator 2007 endpoints within the intranet through the A/V Edge Server. In future releases, Office Communicator 2007 endpoints outside the intranet will be able to communicate with Polycom endpoints. For more information, see the “How Microsoft Envisions the Future of Videoconferencing Interoperability” topic later in this paper.

How Microsoft Envisions the Future of Videoconferencing

Interoperability

The Microsoft vision for videoconferencing interoperability focuses on a non-vendor specific solution. Instead of using videoconferencing vendor interoperability solutions, videoconferencing vendors will implement the Real Time Video (RTV) and Real Time Audio (RTA) protocols in their products and communicate with Office Communicator endpoints natively through the Audiovisual Multipoint Control Unit (AVMCU) Server role. The AVMCU Server role performs the same functions as a traditional MCU and implements the corresponding video and audio codecs for RTV and RTA. The RTV codec is an extension of the industry standard VC-1 codec.

The advantages of this architecture include:

• Vendor-independent videoconferencing interoperability. The AVMCU Server role has real-time audio and video codecs that provide video between the Office

Communications Server 2007 endpoints and the vendor-specific endpoints. The AVMCU Server role will maintain presence status by using SIP with the vendor-specific infrastructure.

• Simplified transversal of firewall and NAT devices with improved security. As in Office Communications Server 2007, the A/V Edge Server in future versions of Office Communications Server will provide a single trusted connection point through which inbound and outbound media traffic can more securely traverse NATs and firewalls by using the industry standard ICE protocol. As other videoconferencing vendors implement the RTV protocol, RTA protocol, and industry standards like ICE and Secure Real-time Transport Protocol (SRTP) powerful unified communications will be possible between all users in the intranet, extranet, and federated networks.

• Simplified administration and management of a heterogeneous

videoconferencing environment. The management and administration is performed

by using the familiar administration tools available in current and future versions of Office Communications Server and Office Communicator. All call or conferencing details can be collected and managed by using the existing reporting tools in Office Communications Server.

The following figure illustrates the interoperability between future versions of Office Communications Server and videoconferencing hardware vendors. This interoperability for endpoints other than Office

Communicator endpoints assumes that the videoconferencing hardware vendor endpoints have licensed the Microsoft audio and video codecs for use in the videoconferencing vendor endpoints. In this case, the videoconferencing endpoints appear as native Office Communicator endpoints.

Videoconferencing hardware vendor device endpoints that implement one of the solutions in the previous bulleted list appear as videoconferencing contacts in the Office Communicator contact list. Other

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videoconferencing and will have the same constraints as they do in Office Communications Server 2007.

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The following table lists the videoconferencing scenarios that will be possible in future releases of Office Communications Server that are not currently possible and are limitations to the TANDBERG and Polycom solutions, as described in Table 4 and Table 6.

Table 7. Videoconferencing scenarios that will be possible in future releases of Office Communications Server

Scenario Description

Videoconferences with endpoints that connect through the A/V Edge Server

Office Communicator endpoints and videoconferencing vendor endpoints with Microsoft-licensed codec that connect through the A/V Edge Server can participate in point-to-point and multipoint videoconferences. Multipoint videoconferences

between endpoints

Office Communicator endpoints and videoconferencing vendor endpoints with Microsoft-licensed codecs can participate in multipoint

videoconferences.

Conclusion

Currently, interoperability between Office Communications Server 2007 and videoconferencing hardware vendors is accomplished by each vendor. This interoperability allows you to:

• Provide widespread access to videoconferencing tools. Users can run Office Communicator 2007 on existing computers with minimal additional equipment, typically a webcam and headset. Also, Microsoft RoundTable can convert a laptop to a conference room endpoint for conducting videoconferences. By using existing computers, more users are able to make use of videoconferencing.

• Simplify the user’s experience in participating in videoconferencing. Office Communicator 2007 provides a consistent user experience. In addition, users can use the familiar meeting scheduling features in Outlook to schedule meetings with users running Office Communicator 2007 or vendor videoconferencing devices. • Enable users running vendor-based videoconferencing products to conference

with users running Office Communicator 2007. Organizations can capitalize on

their existing vendor videoconferencing infrastructure while gaining the advantages of Office Communications Server 2007 and integration with other Microsoft products and services.

• Reduce the length of time for videoconferencing adoption. Users will more readily adopt videoconferencing solutions if they can easily access videoconferencing services. Office Communicator 2007 provides widespread access to

videoconferencing services. The minimal hardware investment per videoconferencing client also helps users provide cost justification for the adoption of videoconferencing solutions.

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For More Information

The following resources can help you learn more about deploying and interoperating with Office Communications Server 2007 in your environment:

• Office Communications Server 2007 Document: Technical Overview at

www.microsoft.com/downloads/details.aspx?FamilyID=09b218ea-6ff6-4679-a117-9767ab98990a&DisplayLang=en.

• Office Communications Server 2007 Document: Planning Guide at

www.microsoft.com/downloads/details.aspx?familyid=723347C6-FA1F-44D8-A7FA-8974C3B596F4&displaylang=en.

• Office Communications Server 2007 Active Directory Guide: Preparing Active Directory, Delegating Permissions and Schema Reference at

http://technet.microsoft.com/en-us/library/bb894697.aspx.

• Exchange Server 2007 Unified Messaging at

www.microsoft.com/exchange/evaluation/unifiedmessaging/umwhitepaper.mspx.

• H.323: Packet-based multimedia communications systems at

www.itu.int/rec/T-REC-H.323/e.

• H.239: Role management and additional media channels for H.300-series terminals

at www.itu.int/rec/T-REC-H.239/en.

• H.264: Advanced video coding for generic audiovisual services at

www.itu.int/rec/T-REC-H.264.

• Computer Supported Telecommunications Applications (CSTA) at

www.ecma-international.org/activities/Communications/TG11/cstaIII.htm.

Office Communications Server 2007 Videoconferencing Interoperability