Lotus Virtual Classroom - Performance Planning Hints

Published 20 May 2003, updated 21 May 2003

Authors: Mike Ebbers


This information describes how to plan for Lotus Virtual Classroom (LVC) performance in a network.


This information, derived from Chapter 5 of IBM Redbook SG24-6842-01, will help in designing a suitable network topology for the deployment of the IBM Lotus Virtual Classroom. It highlights the points you should consider in determining how the product will be used, and also discusses details of the deployment.


  • Who is going to use your live virtual classroom?
  • How do you intend to use your live virtual classroom?
  • What do you intend to use our live virtual classroom for?
  • What is your current network topology?

These questions need to be discussed extensively and transparently between the deployment stakeholders (see Chapter 8, “Roles and responsibilities” in redbook SG24-6842-01, for more information on that subject).

If deployment is in answer to an internal training need and is to run on a LAN, then the network topology is going to be relatively simple. If, however, the deployment needs to connect users on low bandwidth connections to LAN users behind a firewall, then the network topology is going to be much more complex. This will have a major impact on hardware requirements and support.

The Virtual Classroom visible (session) server is based on Sametime technology, and you can refer to existing Sametime deployment documentation and expertise for more guidance. The IBM Redbook Lotus Sametime 2.0 Deployment Guide, SG24-6206, contains an excellent discussion of complex Sametime deployment. Chapter 6, “Deploying Sametime on the Internet”, is of particular benefit.

A basic deployment of IBM Lotus Virtual Classroom requires two separate servers:
  • A management server that hosts the catalog (Domino) and the content (QuickPlace) servers
  • A classroom server that hosts the session (Sametime) server; large or complex deployments will see the need for multiple classroom servers.

However, it is unlikely that there will be a need for multiple management servers, and installation of additional management servers is not documented for the current version of IBM Lotus Virtual Classroom (version 1.0). Considering that the management server load cannot be spread over several machines, it is worth understanding the functions of the two servers.

Note: For an in-depth discussion of the architecture of the Virtual Classroom, refer to Chapter 4, “Inside the IBM Lotus Virtual Classroom 1.0” in redbook SG24-6842-01.

Even the fastest server setup and network topology will deliver poor performance during sessions if the client setup is poor. Proper planning is vital in order to be able to deliver Virtual Classroom services to the appropriate client setup.

Client PC
The client PC provides all of the power required to send and receive Sametime awareness data, instant messages, audio, and video services. All audio and video codec processing is performed on the client PCs. The Virtual Classroom classroom server does not do any manipulation of the contents of data packets sent through it. The local PC also executes the signed Java applets from the classroom server used for providing the session interface.

Given these functions, the client PC must have sufficient power to support demands placed on it by the Virtual Classroom. Almost any current Windows PC with a network connection will be able to handle text chatting, and the object sharing and whiteboard sessions. Slow PCs will take a considerable length of time to start Java applets, however. The demands on the client PC rise sharply when audio and video compression and handling for these functions are introduced.

Ideally, client PCs will run on a Pentium III processor or higher and have memory of 128 Mb or higher. The performance of the instructor's PC is particularly important to the performance of the session for all users; we recommend memory of at least 256 MB.

Client networking
Every IBM Lotus Virtual Classroom service is only as good as its connection to the users. When planning your live virtual classroom deployment, keep your users’ networking capacity in mind. Consider questions such as: Are you using low-bandwidth connections from remote sites? Are all your users in one site, or are they scattered across the world? How congested is your current network?

Table 1 provides a rough idea of which session functions can realistically be used at different network connection speeds. Keep in mind, though, that every network is different, and issues such as network traffic congestion and line speed fluctuations are not considered here.

Restriction: The IBM Lotus Virtual Classroom supports client PCs running only Windows (98 Second Edition, NT, 2000, or XP Professional)

Table 1: Recommended bandwidth and performance levels for classroom session functions
Line Speed (Kbps)Text chat<1 KbpsBroadcast Session
16-128 Kbps
Screen Share/
Whiteboard 3-64Kpbs
2-way Audio
6.3 or 64 Kbps
2-way A/V
16-128 Kbps
<56K GoodAudio OK, video not
View OKOK - listen only
Slow 1 fps
56K-64KGoodAcceptableLive screen share
OK in limited size,
low colors
OK if used with
moderated microphone

Note: Even very low-speed (28.8 Kbps or lower) connections will function very well for online status and text chat functions. Instant message data transmissions are usually measured in mere bytes (far less than 1,000 characters per message). Any lag encountered usually occurs because of routing delays, rather than the actual time required to transmit the data.

Downloading the Sametime Connect client
The Virtual Classroom session is delivered to users through the Sametime Connect client, which is a Java applet run in their browser. The client is about 4 MB in size.

For those working on a low-bandwidth connection, we strongly recommend that you download the Sametime Connect client well in advance of a session. This can be done by going to My Sessions and following the link titled "Click here to test your setup" before attending your first session.

Client browser
Although Netscape 4.7 is supported, performance in practice is faster using Internet Explorer 5.5x or Internet Explorer 6.0 with service pack 1. For up-to-date browser downloads, visit:

Special Notices

This material has not been submitted to any formal IBM test and is published AS IS. It has not been the subject of rigorous review. IBM assumes no responsibility for its accuracy or completeness. The use of this information or the implementation of any of these techniques is a client responsibility and depends upon the client's ability to evaluate and integrate them into the client's operational environment.

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