Chapter 04 Conferencing and Collaboration

8/12/2019 Chapter 04 Conferencing and Collaboration

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Contributors

Project Manager:#usan #. 5radle"

Content Architect:Rui %aximo

Chapter Lead:#eth 0aul

Lead Writer:#eth 0aul

Technical Reviewers:6ao &an, rish lre7a, Tarang %ittal, Mei Lu, Duy Tran, Ramesh

$ara"anan, 8osh %arsha/, 9en/at ddan/i

Lead Editor:2atrina 0urcell

Art Manager:8im 5radle"

Cover Design:8im 5radle"

Production Editor:2ell" 3uller 5lue



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Table of ContentsContributors................................................................................................................................. 4

Introduction.................................................................................................................................. 6

Scenarios.....................................................................................................................................6

Internals....................................................................................................................................... 7

Conferencing Architecture........................................................................................................ 7

How the Components or! "ogether...................................................................................#

Scheduling a Conference....................................................................................................... $%

&oining a Conference.............................................................................................................$4

Audio and 'ideo Conferencing...............................................................................................$(

'ideo Conferencing............................................................................................................23

)ial*in Conferencing...............................................................................................................2+

eb Conferencing and Application Sharing...........................................................................3$

eb Conferencing.............................................................................................................. 32

Application Sharing............................................................................................................. 36

Summar,................................................................................................................................... 3(

Additional -esources................................................................................................................. 3(

otes from the /ield...................................................................................................................3(

Is "here a 2+% 0articipant 1imit for Conferencing....................................................................3(

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Introduction

%icrosoft: L"nc; #erver )*+* provides a complete set of tools that "ou can use forconferencing and colla!oration, including servers and services that support audio and video

conferences, application sharing, we! conferencing, and dial-in conferencing, in addition toclients for connecting to a conference. 3ollowing a !rief introduction of how these tools wor/

together, this chapter will descri!e the technical details of what happens !ehind the sceneswhen a user schedules and 7oins a conference.

Scenarios3undamentall", a conference consists of two separate actionsThis lin/ is hidden !" default?

3or details a!out the differences in using these clients, see 0lanning for 'lients in the L"nc#erver )*+* documentation, http://go.microsoft.com/fwlink/?LinkId=2050!".

conference can support an" com!ination of the following conference t"pes >also calledmodalities?thus ena!ling

we! conferencing?, the conference is alread" configured for we! conferencing. There ma"!e some instances where an administrator wants to disa!le certain modalities for specific

users. 3or example, the compan" polic" ma" !e to disa!le application sharing for users thatwor/ with highl" sensitive data.

If an attendee is an anon"mous user, or the" are dialing in to the meeting, the" ma" !etransferred to the lo!!" until a conference presenter allows them access. dministrators can

also use the CsMeetingConfigurationcmdlet to configure this !ehavior. 3or example, "ou

can configure meetings so that an"one dialing in over the pu!lic switched telephone networ/>0#T$? is automaticall" admitted to the meeting. lternativel", "ou can configure meetingsso that dial-in users are not automaticall" admitted the meeting, !ut are instead routed to

the meeting lo!!". These dial-in users remain on hold in the lo!!" until a presenter admitsthem to the meeting. 3or details, see 'onfiguring the %eeting 8oin Axperience,

http://go.microsoft.com/fwlink/?LinkId=2#$"94% and ial-In 'onferencing 'apa!ilities,

http://go.microsoft.com/fwlink/?LinkId=20$59% in the L"nc #erver )*+* documentation.

The following sections provide more information a!out what happens when a conference isscheduled and 7oined.

Internals

Conferencing Architecture

In a L"nc #erver )*+* deplo"ment, there are several conferencing components that wor/together to provide conferencing functionalit". The" include the 3ocus, 3ocus 3actor", e!

'onferencing service, B9 'onferencing #erver, I% 'onferencing service, and pplication

#haring 'onferencing service. 3igure @-+ shows the process !oundaries for theseconferencing components.

Note.The A/V Conferencing Server can also be collocated with the Front End Server.



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Figure 7-1. Process boundaries for conferencing components

3or a more in-depth description of these components, see the 'onferencing #ervices

section in 'hapter C< Technical verview.

3or more details a!out the !asics of conferencing, including planning for conferencing,

reDuired components, and hardware and software reDuirements, see 0lanning for'onferencing in the L"nc #erver )*+* documentation at http://go.microsoft.com/fwlink/?

linkid=2055$2. If "ou need detailed instructions a!out how to deplo" the various

components shown in 3igure @-+, see eplo"ment in the L"nc #erver )*+*documentation, http://go.microsoft.com/fwlink/?linkid=20$#42.

How the Components Work Together

3igure @-) provides an overview of how the various conferencing protocols interact with theL"nc #erver )*+* components shown in 3igure @-+.

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Figure 7-2. Interaction of conferencing protocols

To help understand this diagram, let=s go over the protocols that are used to move data!etween components. These protocols will !e the !asis for all call flow discussions later in

this chapter.

ignaling Protocols:These are protocols that facilitate session esta!lishment, state andcapa!ilit" exchange, and conference control.

ession !nitiation Protocol "!P#:#I0 is the primar" signaling protocol used !"

L"nc #erver. It defines a standard wa" to perform session setup, termination, and

media negotiation.

Centrali$ed Conferencing Control Protocol "C%P#:'C0 is an E%L-!ased protocol

that provides a thin wrapper around the 'onference Avent pac/age and media

specific extensions. It is responsi!le for various conference control and state

modification tas/s. 5etween the clients and the 3ocus, 'C0 is carried through #I0

inside #I0 I$3 or #I0 #AR9I'A. The 3ocus also uses 'C0 to tal/ to the various

conferencing services. 6TT0# is used as the carrier protocol in these cases.

Media Protocols:These are protocols that facilitate the exchange of specific t"pes ofmedia !etween clients and conferencing services.

Persistent hared &'ject Messaging "P&M#:0#% is the we! conferencing

protocol used for exchanging data colla!oration content and control.

ession !nitiation Protocol for !nstant Messaging and Presence Leveraging

E(tensions "!MPLE#:#I%0LA is used for instant messaging >I%?.

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Real)ti*e transport protocol "RTP#+Real)ti*e transport control protocol

"RTCP#:RT0 and RT'0 allow an B9 'onferencing service to exchange audio and

video streams with conferencing clients. RT0 defines the standard for audio and

video pac/aging. RT'0 provides control information for the RT0 flow. It conve"s

information a!out signal Dualit" for an audioBvideo >B9? conferencing session. The

secure versions of these protocols are secure real-time transport protocol >#RT0? andsecure real-time transport control protocol >#RT'0?.

Re*ote Des,top Protocol "RDP#:pplication #haring 'onferencing service uses

R0 wrapped in #RT0BRT0 to transmit application-sharing data, such as the stream

of !itmaps from the sharer=s des/top to the other conference participants. If another

participant ta/es control, R0 transfers the controller=s /e"!oard and mouse inputs

!ac/ to the sharer=s des/top.

The 3ocus 3actor", shown in figure @-), is responsi!le for creating conferences. hen a userschedules a new conference, the 3ocus 3actor" creates a new instance of the conference in

the conference data!ase and returns information a!out the newl" created conference to theclient. The 3ocus uses the information stored !" the 3ocus 3actor" in the conference

data!ase to act as the conference manager. It is responsi!le for managing the state of theconference, enforcing securit", managing roles and privileges, and providing conferencestate updates to all the clients 7oined to the conference.

'onference information is stored in the #1L #erver-!ased 5ac/ And #erver, which is used to

s"nchroni4e information !etween the 3ocus and 3ocus 3actor".

$ow that we have covered the !asics, we can discuss how this all wor/s. 3irst, we will ta/e

a deeper loo/ into how a conference is scheduled, and then we will tal/ a!out 7oining aconference.

Scheduling a Conference

The default settings for conferences have !een ad7usted to meet the most common

colla!oration demands. %ost importantl", !" default all modalities are ena!led >includingB9, I%, we! conferencing, and application sharing?. 0u!lic switched telephone networ/>0#T$? dial-in conferencing is also ena!led >selected !" default in the default glo!al

conferencing polic"?, and all 0#T$ users are configured to automaticall" s/ip the lo!!">'stn()llers*+p)ssLo,,+on the CsMeetingConfigurationcmdlet is set to true?.

L"nc #erver )*+* uses an utloo/ add-in, nline %eeting dd-in for %icrosoft L"nc )*+*, toschedule conferences. This add-in is installed as part of a !asic L"nc client installation. ith

this add-in, utloo/ can use L"nc 0Is to communicate directl" with the 3ocus 3actor" on

the 3ront And #erver, thus simplif"ing the process of scheduling and configuring newconferences. 3or details a!out configuring the add-in, see 'ustomi4ing the nline %eeting

dd-in for L"nc )*+* in the L"nc #erver )*+* documentation,

http://go.microsoft.com/fwlink/?linkid=2#"#9$.

$ote the following when using utloo/ to schedule conferences #?

o upported *edia t-pes

o Authori$ation t-pes "including loc/ed, invited attendee, m" compan", and

ever"one?

The conferencing data is contained within two data'ases: RTC and RTCD-n.

The infor*ation listed previousl- is stored in real)ti*e co**unications

"RTC#. The RTCD-n data'ase contains the run)ti*e conference state. This

data is transient and will 'e re*oved as soon as the conference is over.

Warning.%o" sho"ld not modify the data located in these databases.

The 3ocus will access the information located in RT' when the first client attempts to

7oin the conference.

Note.The conferencing database does not maintain calendar information (such as conferencestart and end times and recurrence). Instead, conference calendar information is maintained bthe scheduling client or in !icrosoft "#change $er%er. &ecause the 'ocus 'actor does not

collect this information, it treats scheduled and adhoc conferences in the same wa.

C. The 3ocus 3actor" sends a )** 2 response that includes conference information

such as the meeting URL and dialFin conferencing num!ers to the utloo/ add-in.

This information can then !e included in the meeting invitation.

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In L"nc #erver )*+*, meeting URLs are discovera!le, eas" to remem!er, and eas" to

communicate. Aver" URL, for !oth pu!lic and private conferences, contains the

following structureRT'0? or the encr"pted #ecure Real-time Transport 0rotocol>#RT0? and #ecure Real-time Transport 'ontrol 0rotocol >#RT'0?. &ou can set the reDuired

level of encr"ption !" using the -ncr+ptionLeelparameter of the et)CsMediaConfigurationcmdlet. 3or details, see #et-'s%edia'onfiguration in the L"nc

#erver )*+* documentation, http://go.microsoft.com/fwlink/?linkid=2#5504.

There are three conferencing policies that affect the client=s experience when connecting toa conferenceI'A? chec/s,

and use the matching capa!ilities included in the #0 offers to initiate a media connection.

This process is shown in figure @-@.

Figure 7-7. A client initiates a connection to the A Conferencing Ser$er.

$ow let=s ta/e a closer loo/ at the steps shown in figure @-@.

+. The client uses the information it receives from the 3ocus during the 7oin process to

initiate contact with the B9 'onferencing #erver. To do this, the client first em!eds

a 'C0 adduser reDuest in a #I0 I$3, and then sends the reDuest to the 3ocus. The

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reDuest includes a parameter that specifies whether the invitation to 7oin the

conference is dial-out or dial-in. In a dial-in reDuest, the B9 'onferencing #erver

receives the reDuest. In a dial-out reDuest, the B9 'onferencing #erver sends out

the reDuest.

). The 3ocus ta/es the E%L 'C0 adduser reDuest out of the #I0 reDuest, wraps it in

6TT0#, and forwards it to the B9 'onferencing #erver. The B9 'onferencing #erver

sends a 'C0 adduser response !ac/ to the clientNrouted through the 3ocusNthat

tells the client to 7oin the conference.

The B9 'onferencing #erver has now created a logical representation of the client

and is waiting for the client to send a media offer.

C. The next step is to set up the media connection. fter receiving the success

message, the client em!eds the #0 offer in a #I0 I$9ITA to the focus, which then

forwards this information on to the B9 'onferencing #erver.

The #0 ffer contains information >called an mline? a!out client support for each

modalit" supported !" the B9 'onferencing #erver, including audio, video, and

panoramic. Aach m-line contains some com!ination of the followingthe server determines this !" reading the-n),le'2'ideoparameter on the conference polic"?, the B9 'onferencing #erver will

respond onl" to the offer with audio. If video is ena!led, the conference polic" can furthercontrol the resolution of the video supported for the conference !" using the

1)xideo(onferenceesol3tionparameter. In L"nc #erver )*+*, this can !e set to either'I3 or 9M. The default value is 9M.

5ased on the conference policies settings, the B9 'onferencing #erver will respond to theclient in the preceding example with the following capa!ilities lineMRUU? that corresponds to the ttendant instance in the pool where the

conference is homed. If the MRUU does not match the MRUU of the ttendant, then

the conference is !eing hosted in another pool. In this case, the ttendant !lindl"

transfers the call to the correct MRUU, which corresponds to the correct ttendant

that is serving the pool where the conference is homed. s a result, the remote

pool=s ttendant will serve the remainder of the interactive voice response >I9R?.

The process of transferring !etween ttendants is called interpool transfer. In L"nc

#erver )*+*, the ttendant can recogni4e incoming !lind transfers that correspond

to interpool transfers and resume from the appropriate stage in the I9R. This

functionalit" ena!les coexistence and interoperation !" ensuring that the version of

ttendant serving the call is the ttendant serving the pool where the conference is

homed.

Note.The Attendant will not transfer the call to an older version of Attendant.

C. fter 7oining the conference, the ttendant #U5#'RI5As to roster updates to o!tain

information a!out the current state of the conference. This is important if, for

example, the conference was scheduled as an anon"mous conference, !ut was later

loc/ed.

The ttendant then determines whether to prompt the user for identification. If

authori4ation is reDuired, the caller is as/ed to provide credentials. If the caller does

not provide the correct credentials, the" are routed to the lo!!". 5ecause promptingfor identification can !e confusing to users, unless the conference is Invite nl" or

Loc/ed, or the server policies don=t allow anon"mous 7oin, the ttendant will attempt

to 7oin the user to the conference anon"mousl" without as/ing for identification.

s part of this step, the ttendant as/s the user if the" are the leader, and if "es

directs the user to press Q=. The user is then as/ed to enter a personal identification



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num!er >0I$?, or if the" are not the organi4er, !ut instead another leader, the" are

as/ed to press Q= again and enter a phone num!er, extension, and 0I$.

ll dialogs that are responsi!le for 0I$ communication !etween the ttendant and

the 3ocus use the User 0in #ervice >User0in#vc?. User0in#vc is responsi!le for

managing 0I$s, including loc/ing them when there are too man" failed attempts or

expiring them when server policies dictate that 0I$s have an expir" >!" default the"do not?. The 0I$ that is used to authenticate the user is also the same 0I$ that the

user uses to unloc/ their des/ phone.

Note.This is not the same I' that is "sed for >icrosoft E4change scenarios s"ch as voice mail.

&ou can use several different policies to control 0I$s, including control of their

complexit", expiration, and histor". n administrator can reset a user=s 0I$ using the

0I$ 0olic" page in the L"nc #erver 'ontrol 0anel. 3or details a!out changing a 0I$,

see %odif" the efault ial-in 'onferencing 0I$ #ettings in the L"nc #erver )*+*

documentation, http://go.microsoft.com/fwlink/?linkid=2#"200. 0I$s can !e one of

the following stateseither a tone or the name of the person entering or exiting the

conference?. user can turn announcements on or off in the conference, !ut the"

cannot change the st"le of announcement.

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. The 'onferencing nnouncement service invites the 0ersonal 9irtual ssistant into

the conference.

fter the user=s state in the roster maintained !" the 3ocus is connected, the

ttendant attempts to 7oin the call to an B9 'onferencing #erver for audio. 5ecause

the 3ocus alread" provisioned an B9 'onferencing #erver for the conference, it can

use the conference information populated !" the 3ocus to find the correct B9

'onferencing #erver. ttendant sends another 'C0 Add3serreDuest on !ehalf of

the user, this time directed to the B9 'onferencing #erver. This invitation has a

refer-to-URI with RA0L'As.

This causes the B9 'onferencing #erver to send an I$9ITA with referred-!" to the

%ediation #erver. This invitation replaces the audio leg !etween the %ediation #erver

and ttendant, effectivel" 7oining the user to the conference. hen this dialog is

complete, the user can hear conference audio and participate in the conference.

The dial-in conferencing process is summari4ed in the call flow shown in figure @-+*.

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Figure 7-1. 0ial-in conferencing call flo"

3eb Conferencing and Application Sharing

L"nc #erver )*+* supports a rich mix of data colla!oration possi!ilities. Users can share andcolla!orate on documents, such as %icrosoft: 0ower0oint: presentations, !" using thee! 'onferencing service. dditionall", users can ta/e advantage of the pplication #haring

'onferencing service to share all or part of their des/top with each other in real time,ma/ing it seem as though the attendees are gathered around the same ta!le in the

conference.

The next two sections discuss technical details associated with the e! 'onferencing and

pplication #haring 'onferencing services.

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Web Conferencing

The e! 'onferencing service manages conference data colla!oration, including native

support for 0ower0oint presentations, document sharing, white!oard, polling, compliancelogging, annotations, and handouts. hile scheduling and 7oining a conference remain the

same as with other modalities, the client communicates with the e! 'onferencing service!" using the 0ersistent #hared !7ect %odel >0#%? protocol. 0#% is a custom protocol

that is used for transporting we! conferencing content.

&ou can use we! conferencing tothat is,

users not currentl" logged on to "our networ/? are allowed to save handouts, slides,

and other conference content. The default value is True. This setting applies to the

user who organi4es the conference< if set to 3alse, no conference created !" a user

affected !" this polic" will allow external users to save content. 6owever, the user

can ta/e part in other conferences where external users are allowed to save content.

n administrator can modif" these policies !" using the et5CsConferencingPolic-

cmdlet.

3igure @-++ illustrates the !asic movement of data !etween the conferencing components.



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Figure 7-12. 4etadata file share

The e! 'onferencing service creates these folders and su!folders when it receives

a 'C0 addConferencereDuest from the 3ocus. If a folder for an organi4er does not

exist, the e! 'onferencing service creates a new organi4er folder. If a folder for an

organi4er alread" exists, the e! 'onferencing service creates the conference

su!folder !elow the existing organi4er folder. If a folder for a conference does not

exist, the e! 'onferencing service creates a new conference folder. If a conference

folder alread" exists, the e! 'onferencing service saves the metadata files in the

existing conference folder.

hen the e! 'onferencing service needs to create a metadata folder for aconference, it extracts the organi4er URI from the addConferenceE%L. The URI is

passed as input for a hash function. The result of this call is used to search through

the su!folders of the metadata root folder to determine whether there is alread" an

existing organi4er su!folder. If no organi4er su!folder exists, the e! 'onferencing

service creates a new one.

The conference folder contains all the information that is used !" e! 'onferencing

service to recreate the content of a conference.

Content file share:The content folder stores the content that is shared !etween

the e! 'onferencing service and clients using the e! 'omponents #erver. The

content folder contains the followingeither anon"mous

users or federated users? are allowed to ta/e control of shared applications or

des/tops. If this setting is set to true, it determines that anon"mous users can ta/e

control of a des/top. This setting is enforced at the per-user level, and for !oth

conferences and peer-to-peer communication sessions. That means that some users

in a session might !e allowed to give up control of a shared application or des/top to

an external user while other users might not !e allowed to give up control.

n administrator can modif" these policies !" using the et5CsConferencingPolic-cmdlet.

uring a conference, if the pplication #haring session ends due to a connection error on

the media channel, the following diagnostic code is returned

Documents

Chapter 04 Conferencing and Collaboration