What it Took to Become an SC Global Constellation Site in 2001

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.Here are three things you needed to do.

join community     build a node     giving back 

Join the Community__________________

Build a Node__________________

The next step to becoming an SC Global Constellation site is to build your own Access Grid node. The place to start is the Access Grid web site: http://www.accessgrid.org

Here, you will find technical specifications, documentation, software downloads, tutorial slides and most everything required to build an Access Grid node. Building a node requires committing a room to the purpose, outfitting the room properly, acquiring the specified equipment, installing it and learning the AG operational protocols.

Space

Assuming you will be building your node (to-date, there are no third party vendors specializing in AG), you must first decide on the space you want to use and on the display technology - front or rear projection. An AG node is a designed space and so you should conduct a planning session and a site survey concentrating on the each of the following issues:

Display Wall – front vs. rear projection

-Rear projection works well, but requires a special screen and more space than a front projector screen.
-Front projection requires that projectors be hung from the ceiling, which can sometimes be a difficult task. Good projector mounts are a must! If you attempt to use racks or place projectors on tables, the light cones can become too intrusive and difficult to keep in alignment. Uni -strut mounted in the ceilings to hang the projectors is used by many sites and works well.

There is a projector spreadsheet accessible via www.accessgrid.org to help you determine the amount of throw required for the various size screens in either front- or rear-project scenarios. If you would like to reduce the amount of throw required in a rear project system, you can use a system of mirrors.

Front projection requires a suitable display surface, but it is suggested that you test a projector before deciding on a wall surface. We suggest installing a surface called Walltalker that is hung like wallpaper and makes a nice display surface that you can also write on as a whiteboard. The cost of this surface is approximately $25 per linear foot in 5’ wide rolls.

In order to participate in AG sessions, it is suggested that you use more than two projectors, as two will not provide the same sense of presence as three or more may.

Room Size and Architectural Requirements

It is strongly recommended that you obtain a dedicated space/room for your AG node. Below are some of the factors to be considered when determining your space and architectural requirements;

• Room size - Room size will depend on the size of the viewing area. As an example, Argonne uses an 18 ft. display wall with an image about 5 ft. high. Using the 2xH rule, the minimum viewing distance is about 10 ft. Place your audience area approximately 12 feet from the screen. In smaller areas, a 12x3 display is satisfactory. Nevertheless, in this case, bigger is better and we think you will prefer the 18 ft. wall.

• Sound/noise - Background noises such as fans and other clutter makes the sound difficult to understand on both sides of the AG session. If you can’t get a quiet room, we suggest you consider some sound abatement techniques, such as carpeting, baffles, screens around noisy equipment, etc.

• Lighting - Unfortunately, the lighting requirements work at cross-purposes. The room should be well-lit enough for people to feel comfortable working for extended periods of time as well as for the sake of the video cameras, but can be uncomfortable if pointed directly at people’s faces. Careful consideration should also be taken to ensure that the lighting does not wash out the display.

• Cables - Adequate space should be allocated for cable trays or runs in order to manage the amount of cables required for an AG node.

• Cameras – Using small commercial or custom camera mount platforms will alleviate footprint problems that tripods have caused, while saving space in front of the display.

Furnishings

Enough comfortable seating and workspace for 5-10 people should be provided in front of the screen. It may also be a good idea to strategically place network drops and pc power supplies around the room. The AG community will often say that a couch is a critical requirement, but of course, not everyone can have a couch in their room. Couches are recommended among the AG community because it makes the space more inviting for casual use, the preferred method of operating.

Network and Bandwidth Requirements

If connectivity to the Alliance (NCSA) Access Grid network is desired, a connection to either the vBNS or Abilene is currently required and the bandwidth minimum increases to accommodate moreAccess Grid nodes.

Bandwidth requirements are variable based on the number of separate video and audio feeds per virtual venue (multicast group address). In practice, a network of 6-10 persistent AG nodes generates approximately 10 Mbit/s of traffic, while running idle with no user interaction. Bandwidth climbs when nodes are in use due to increased motion in video streams, increased use of audio and additional sites joining.

During the Network Challenge at SC’2000, the Alliance access-grid network generated approximately 100 Mbit/s of video traffic by increasing the frame rate and quality of the video encoding.

The minimum available bandwidth to each site should be greater than 10 Mbit/s for less than 5 sites in an access-grid network. Each additional node increases the minimum requirement by approximately 1.5 Mbit/s per site (3 x 300-400 Kbp/s video streams, plus a 300 Kbps audio stream).

Routing Protocols

A robust and scalable multicast routing infrastructure is required to run an AG network. The most stable and scalable combination currently is to use PIM-SM in the LAN and PIM-SM / MBGP / MSDP in combination for peering between Autonomous Systems.

It may be necessary to check with the appropriate router vendors about the release requirements to support these protocols.

Native IP Multicast

• The multicast service uses state of the art multicast protocols such as PIM sparse mode, MBGP, and MSDP. PIM sparse-mode offers a scalable solution to distribute multicast traffic based on explicit joins there by reducing the network load and optimizing the multicast tree distribution. MBGP offers a mechanism of exchanging multicast routes across different domains with all the routing management features that are inherited from BGP. MSDP allows multicast sources to be announced across multiple peering domains.
• Advantages- information sent based on receiver joining group (explicit join). The flood and prune nature of DVMRP does not scale. MBONE tunnels are typically constructed using DVMRP. This topology is not compatible with the goals of the AG deployment.
• Start a NLANR Multicast Beacon (http://dast.nlanr.net/Features/Beacon) at your site at or near the place where you will build your AG node early and keep it running.  Included in the AG distribution, this is a tool that monitors multicast connectivity between sites. Basically, it is a piece of Java code that transmits and listens to the multicast channel and sends its results to a central server. This is vital in order to ensure that multicast is operating properly to your site and to your room. It is easy for AG operators to use and provides a quick snapshot of the current state of multicast connectivity among a group of sites.

  Computing equipment	$13,000
  Network equipment	$ 1,000
  Other computing equipment (monitors, KVM switch)	$ 2,000
  Large node audio configuration	$11,000
  Video cameras (4 Sony EVI-D30)	$ 6,000
  Projectors (3 Epson 710c)	$16,000
  Total	$49,000

  Assembly

  Room preparation is always site dependent and we can’t give any advice on how long your room will take to prepare. However, assuming your room is (or has been made) satisfactory, installing the gear is a matter of mounting and aligning projectors, running cables, mounting cameras and microphones, and assembling the computing gear. This part of the process should take a week or less for one full-time person.

  Networking Personnel

  Networking staff at all constellation sites, and the transit networks involved, need to do the preparatory work for getting multicast configured and working across all sites in an Access Grid network. This work may involve configuration changes, router code changes and possible new networking hardware.

  It is also necessary that networking staff along all paths be available to monitor and troubleshoot multicast problems, and generally treat multicast connectivity as a production service.

  There are two roles to fill that are necessary at each site in an Access Grid network in order to support the operation and maintenance of the nodes. These roles are not full time and are often fulfilled by partial reassignment of existing personnel or by using students.

  Senior Technical Support

  This person will be responsible for the Access Grid node’s operation and maintenance including the following roles (many of which will be coordinated with the SC Global Committee):

  • Understand the Access Grid technology and how to fully troubleshoot the system, including the video and audio hardware, the audio echo-cancellation system, the Access Grid software, distributed power point and understand the multicast beacon output.

  • Operate the AG node during events

  • Coordinate the scheduling of events

  • Plan and execute pre-event testing among the sites

  • Perform hardware and software upgrades to the system.

  Technical Support

  This person would assist the Senior Technical Support person in the operation and maintenance of the node, including the following specific emphasis:

  • Troubleshoot technical problems during pre-event testing and AG events

  • Operate the AG node during events

  • Fine-tune AG sub-systems to optimize performance.

  Give Back__________________

  • We encourage SC Constellation sites to organize local workshops and programs that combine SC01 with local material. We would like to know what kind of audience you hope to bring to SC Global, so the SC Program Committee can plan accordingly.

  • When you have an Access Grid Node, your participation is not limited to SC2001. You can participate throughout the year in the tutorials, lectures and other open events regularly scheduled on the Access Grid. More importantly, you can develop new programs from your own expertise to share on the Access Grid. Soon, we expect to see multiple AG domains for different interest groups, providing more opportunity for new groups to participate. Being a content provider is one way of becoming part of the AG community.

  • You can also give back by being Access Grid developers. The Access Grid is an open source project. Although the core development is in the hands of the original designers, much work is required for new applications in everything from spatialized audio to domain specific interactive tools. New users bring new application requirements and hopefully, new applications developers. At the Access Grid retreat in January, there will be technical discussions about new directions and applications. Users will be able to sign up for development responsibilities in those areas that parallel their research interests.

  • A third way to give back is to organize or participate in human factors studies. We believe that group interactions are different and more complex than individual ones and we are interested in research on how the Access Grid can provide support for these types of interactions.