When planning the videoconferencing network for the Cell Migration Consortium a number of issues were considered.

1. Connectivity Mode: that is, ISDN (H.320 Standard) or IP (H.323 Standard) or Web-based (Proprietary)
2. Vendor(s) for endpoint hardware/software and the central GateKeeper and Multipoint Control Unit (MCU).
3. Technical and manipulative requirements to be imposed on end users
4. Costs to be incurred for initial setup and for end user training

While ISDN may be useful in a business context where the quality of internet connection is highly variable, the existence of Internet2 in academic communities makes quality H.323 IP videoconferencing the best choice.

Endpoint products from the major manufacturers of IP videoconferencing equipment were researched. VCON was chosen because of the PC based nature of their videoconferencing products, their integrated data sharing and their corporate commitment to IP. The elegance of the VCON system is that an end user unit can be used on the investigators desktop or thrown into a bag with a laptop to be used when traveling or on sabbatical. Additionally, the easy application sharing (T.120 standard) included with the VCON product made it very desirable for the Consortium's purposes. Important in the selection of any vendor is accessible after sales technical support, videoconferencing is an emerging technology and on going technical support is a very important component, VCON has proven very supportive in this regard.

Another important component is the GateKeeper. This server based software acts like a telephone exchange (PBX), keeping track of the participants in the network and facilitating connections. The Consortium uses a VCON Media Exchange Manager, (MXM). The MXM maintains a database of users and their current IP numbers. This allows users with DHCP, dynamically assigned IP numbers, to be found without first having to email their current IP number to possible communicants. The MXM also produces an automatically updated address book for end users. The list contains all individuals logged to the server, with those that are "online" and ready to receive a video call highlighted in green. A major capability provided by the MXM is the ability to make adjustments, remotely, in the videoconferencing software configuration on the end users computer. This feature essentially enables centralized technical support for all end users and greatly diminishes the technician strain on the remote institutions. Many in-meeting difficulties can be corrected "on the fly" using this feature. Additionally, selecting a GateKeeper which is produced by the same vendor that provides the endpoints helps reduce problems, since software versions and compatibility issues are known about and solutions are generally quite rapid.

Another major component is the Multipoint Control Unit (MCU). The MCU is a dedicated device that sits on the network and acts as a suite of virtual meeting rooms. The end users are routed to a particular meeting room by the MXM when they dial an agreed upon address. The MCU accepts the signals from all of the participants, blends them and then sends the assembled image back to all of the users in the meeting. Again, there are a number of manufacturers of MCUs and research and testing was performed to decide which would be most appropriate for the Consortium's needs. The Consortium uses a Cisco 3540 (also sold as RadVision ViaIP), which is a robust chassis populated with two MCU boards capable of 100 simultaneous users each, a T.120 board for large scale application sharing, and a Rate Matching Module (RMM). The RMM allows a bandwidth challenged user to enter a multi-site meeting without pulling the bandwidth for the other users down, which would happen were this unit not to be used. Instead, the meeting is resampled for the problem user and they are able to participate with the signal optimized for their use.

The Consortium goal was to achieve, as closely as possible, a turnkey setup for the end user. The VCON ViGO kit was sent to all participants, along with a PowerPoint picture book showing step by step how to install the software and get the unit running. Once the VIGO was successfully logged into the GateKeeper, each end point was configured to the network. To date approximately 50 endpoints have been set up in this way, without the need to travel to any of the locations for installation or debugging purposes. Within the last 18 months, institutional firewalls have become a problem. Recent worm and virus difficulties have led many institutions to implement firewalls to limit their exposure to external attack. Unfortunately, these firewalls also block the data ports necessary for H.323 videoconferencing. The differing brands of firewall and the varying structures of the network environments make it difficult to have a simple, all purpose, solution. Good communication with the Institutions and a willingness on the part of the network firewall administrators, have enabled work-arounds to overcome these issues and permitted continued videoconferenceing. These firewall work-arounds may include putting the videoconferencing computer "outside" the firewall; opening up the firewall ports to the computer from specific outside IP numbers; opening up the fire wall to the computer by appointment, for a specific period of time; and permitting bi-direcitonal traffic to the computer through the firewall only when the computer has initiated the connection with the remote site.  All of these work-arounds must be accomplished by the particular institution involved.

The Consortium's intention was to keep the major investment at the center of the network, so that users could be added inexpensively when needed. This arrangement has enabled the Consortium to leverage its investment to help others. Since the technological expertise is centralized, each researcher does not need to have a trained technician on hand. The end user software is so simple, most users are very comfortable with it within minutes. Additionally, and very importantly, this approach has enabled to Consortium to act as a resource for other associated research groups in the field, facilitating communication between those groups as well as with Consortium members.

Details on the technology chosen by the CMC

VCON/Meeting Point/IPNexus

Publications on this system & alternate systems

Article reviewing CMC system