1. The Alliance Access Grid Michael Grobe, Assistant Director Academic Computing Services The University of Kansas [email_address] April 2001

2. The Access Grid is an Internet-based model for video conferencing developed by the Future Lab (FL) within the Mathematics and Computer Science (MCS) division of Argonne National Laboratories (ANL). The Access Grid is an extension of the Alliance Computational Grid which is a distributed computing environment designed to provide convenient access to high performance computer systems to any network user.

3. Basic functionality An Access Grid "node" is a conference room or small auditorium, provisioned with the equipment to participate in a multipoint video conference. Audio Video Whiteboard Screen sharing Application sharing

6. The Access Grid will support distributed meetings, collaborative work sessions, seminars, lectures, tutorials and training, scaling from 2 to 20 sites exchanging up to ~80 video streams. The “design point” is group-to-group communication (thus differentiating it from desktop to desktop based tools that are focused on individual communication).“ The Access Grid includes the notion of a "persistent" video conferencing venue, a conferencing site operating continuously (and comfortably ), accessible to a wide audience of users on an ad hoc basis. Open source and multi-platform software is employed almost exclusively.

8. vic and rat were developed as part of the Internet Multicast backbone, or MBONE, which provided multicast services over the unicast Internet backbone (using "tunnels", or "bridges", between multicast nexus sites). The Access Grid model relies upon the ability to send and receive Internet Multicast traffic to and from all conference nodes. An individual vic stream will generate from 10Kbps to 4Mbps of network traffic. A large conference may generate 20Mbps.

11. The Distributed PowerPoint software The Argonne Distributed PowerPoint software allows a single presenter at one node to control PowerPoint applications running on computer systems located at other Access Grid nodes. For example, a conference speaker can run PowerPoint along with the Distributed PowerPoint master software on her laptop computer at the podium of one of the AG sites. When the speaker changes slides, the master will notify the DPPT server, which will notify DPPT clients running on systems at other nodes which will, in turn, direct their local PowerPoint programs to change slides.

12. Note that this approach requires that some PowerPoint features be removed or disabled prior to presentation, because Distributed PowerPoint cannot deal with them. (See later discussions of VNC and "scan conversion" for alternatives.) The DPPT clients can operate on PowerPoint slidesets published on a Web server, or on local copies of the slidesets.

13. The MUD software Operators at each site involved in an Access Grid conference typically keep in touch by using software originally developed for online "role-playing" games generically called Multi-User dragons and Dungeons" games, or "MUDs". (MUD functionality is similar to that of Inter net Relay Chat operating with access control.) Argonne runs a MUD server for use by Access Grid operators who run MUD clients on their desktop systems. tkMOO-lite is currently the recommended MUD client for this purpose, but others, such as Tiny-Fugue in the Unix environment can be used as well.

16. If your systems are Virtual Venue-enabled, the display system operator can click on a conference room name and the vic, rat and MUD applications running on the video display, video capture and audio processing systems will all be started with target addresses and settings appropriate to the selected conference room. This coordination is accomplished by running an "event server" and the event controller on the display system, along with "event listeners" on the video capture and audio processing systems.

17. Virtual Network Computing (VNC) VNC allows users to share monitor screens over the Internet in a variety of modes. In the Access Grid environment, VNC allows a speaker to share his/her podium laptop with Access Grid display systems which can then project it at remote nodes. This is useful when a speaker wishes to give real-time demonstrations or present PowerPoint slides that include "fancy" features, such as animations, that cannot be displayed using Distributed PowerPoint. VNC employs a client server architecture, and there are clients and servers available for Windows98/NT/2000 and Unix operating systems.

18. Basic system configurations The AG model uses a collection of commodity components to provide various services. To assure optimal responsiveness individual functions (video capture, video display, audio capture and presentation) are placed on separate computer systems. There is a variety of hardware and software configurations that can provide the required video conferencing functionality.

20. The Gentner AP400 Echo Canceller Within the Access Grid model, signals from and to attached audio equipment are funneled through an "echo canceller" made by the Gentner Communications Corporation , to eliminate certain kinds of echoes produced during networked conferencing. (We leave our mics on.) It is probably fair to say that the Gentner echo canceller is the major component of the audio conferencing system Networks of Gentners work together to provide useful audio signal exchanges.

22. Echo canceller control computer The audio control computer runs Windows 98 and uses custom Genter Control Software to control the Gentner mixer/echo canceller. See http://www.gentner.com for more details.

36. Additional Info The Access Grid web site: http://www.fp.mcs.anl.gov/fl/accessgrid/ For a more detailed version of this talk see: http://www.cc.ukans.edu/~acs/docs/access-grid-node/ For more information about vic and rat see: http://www-mice.cs.ucl.ac.uk/multimedia/software/vic http://www-mice. cs . ucl .ac. uk /multimedia/software/rat Acknowledgments Some of the material for this web page has been taken from the Argonne Labs web site listed above, or from documents provided via that site.