Project CUMBONE: CERN Unicast MBONE server

Project description

To provide workstations inside the CERN LAN (which is protected from IP multicast traffic) with the capability to show (audio and video) broadcasts on the MBONE. This should be done with standard X applications, and without the need for the workstation to have it's kernel modified. The broadcasts should be available to owners of Unix, VMS, MSWindows and WindowsNT machines via an automated booking scheme that ensures appropriate network bandwidth. You can see a slide showing the proposed network configuration, although the text on this slide is now out of date as ideas have evolved. The following information is fully up-to-date.

Current Status

The current state of play on 22/4/94 is as follows:
  • A VAX workstation ( is connected to the same Ethernet segment as, a Sun machine with mrouted and a tunnel from
  • Work on a promiscuous mode IP packet forwarder that runs on vscn15 is complete. This forwarder allows the encapsulated IP multicast packets being sent by the mbone machine to sunmed to be picked up and then unicast to a workstation CUMBONE client ( inside the CERN LAN.

    This is done by first removing the encapsulation header put there for the tunnel, and then replacing the IP multicast destination address in the resulting packet by the IP address of the CUMBONE client. After recomputing the header checksum, and specifying the Ethernet address of the client in the packet header, the packet is sent back out on the network and is thus received by the client. In a production environment the packet would be sent out on a different adapter, preferably FDDI, directly connected to the main CERN backbone.

  • The nv program (v3.2, by Ron Frederick) has been ported to VMS. This is the standard tool used to receive (and send) video streams on the MBONE. The port involved an installation of Tk3.3 and Tcl7.0 on Alpha VMS (no mean feat in itself!). The NV program runs on the CUMBONE client, and listens for packets from the IP address and on the port number of the machine sourcing the video stream. (Today, the stream of interest is on, port 34744, the CHEP Speaker video stream.)