CERN Accelerating science

Packet-Mode Videoconferencing

Packet-mode videoconferencing makes use of workstations equipped with audio/video capabilities and connected to the regular data packet networks. It can be cheap, flexible and well integrated in the users' computing environment. The services can be supported on a wide range of UNIX workstations. Public-domain software is available, and ensures good interoperability.

However it must be stressed that:

• This is a fairly new technology which is not mature for immediate full production. The videoconferencing software is not always as stable as it should be, and quality is not only dependent on the available static bandwidth, but also on the instantaneous network load, which is often unpredictable.
• Packet-mode videoconferencing cannot work for all the destinations: only organizations connected to CERN with a sufficient bandwidth may join the pilot activities. A minimal audio-video stream requires of the order of 200 kilobit per second. In practice, in view of the current network connections, services can be confidently attempted with the following organizations: IN2P3 in FR, INFN in IT, organizations in CH connected to the SWITCH network, and most of the organizations in the USA. Communications with other countries have to be considered on a case-by-case basis.
• Within CERN the systems involved are, for the moment, restricted to dedicated stations supported by either collaborations or CN division. Supporting individual on-site stations is not yet feasible for technical reasons.
• There are two types of packet-mode teleconferencing activities: those organized autonomously by collaborations (ATLAS, CMS) with CN assistance, and those centrally organized by CN as described in the next paragraph.