1. An Instantaneous Introduction to the Alliance Access Grid Michael Grobe Assistant Director Academic Computing Services The University of Kansas September 2000

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.

4. The Access Grid will support large-scale distributed meetings, collaborative work sessions, seminars, lectures, tutorials and training. The Access Grid 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 accessible to a wide audience of users on an ad hoc basis

6. To achieve this functionality the Access Grid model relies upon the ability to send and receive Internet Multicast traffic to and from all conference nodes. The Access Grid is based on software (vic and rat) 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).

9. Note that vic may be run in such a way that it only receives video transmissions or only sends transmissions; it is not required to do both at the same time. For more information about vic see: http://www-mice.cs.ucl.ac.uk/multimedia/software/vic

11. rat displays a list of connected participants and identifies who is speaking and who is listening at any given time. For more information about rat see http://www-mice. cs . ucl .ac. uk /multimedia/software/rat and the Access Grid web site.

12. 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. 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.

14. 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.

15. 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.

16. 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. tkMOO will run on both Windows and Linux systems, so it may be be run on any of the AG component systems described below.

18. The Beacon at each node connects to a Multicast group and collects latency, loss, and packet misordering statistics from all other beacons connected to that Multicast group and sends them to the Beacon server. The Beacon viewer displays these traffic statistics as a matrix showing traffic to and from each Beacon attached to the server. (There is also a web-based Beacon.) At KU the Beacon is running on the AG node's video capture system.

20. 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.

21. 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.

22. Although not part of the original Access Grid canon, VNC has been employed during several Access Grid conferences, and shows promise for future applications. VNC eliminates the coordination effort required to display Distributed PowerPoint slide sets. (No files need to be downloaded ahead of time and no slide synchronization is required.) In general, update times are a function of the number of pixels changed and the number of remote viewers (as well as avaible bandwidth), so VNC will not be appropriate for all applications. Instructions for setting up a VNC relay, are presented in Using Unix-based VNC to relay other VNC traffic .

23. 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:

29. 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. Within the KU ACS node, this function is provided by a 133MHz PC.

31. The KU ACS Podium laptop is connected to a "scan converter" that can convert the VGA/SVGA signal generated by the laptop to NTSC video expected by video capture cards. The CORIOscan Select from TVONE is lists for around $495, and can be used to produce a reasonably high-resolution image (1280x860).

38. 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/ 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.