Multicast-Unicast Reflector

Relatively few Internet users today have direct access to multicast services and networks such as MBone, the multicast-enabled part of the Internet. Multicast-Unicast Reflector is a system which makes it possible to participate in multicast sessions without direct access to MBone, and implements this functionality in a simple fashion even for inexperienced users.

In short, a multicast-to-unicast packet reflector joins chosen multicast groups and replicates the data traffic to a given set of unicast addresses. This unit is controlled by a modified RTSP server, making the WWW-integration simple. This work is done in cooperation with the Interactive Multimedia Group of Apple Computer, Inc. and the MECCANO project.

You may wish to view a short architecture and functionality presentation.

Documentation

• Paper with an introduction to the system architecture and implementation. Submitted to PROMS2000.
• Reflector Session Protocol description
• A brief description of the network activity of the system
• Outline of a minimalistic client

System Demonstration

• Regular, open multicast sessions as seen at the Department of Informatics

Download instructions

To test the system, you need to download the RTSP Controller application (RTSPC). Three platforms are supported per today, you may simply download the needed binary file. RTSPC should start automatically when you choose a session provided in "System Demonstration" paragraph.
If you would like to try all components (as described in "Documentation" paragraph) download the "for the providers" files below. Decompress and run them in the given sequence, following the information provided.

Note: This software is developed as a part of research and educational projects. We have no experience of any problems caused by its usage. In particular, RTSP Controller is a simple GUI-based client application and safe to use.
However, the Reflector, SAPListener and the RTSP server are open network applications running non-secret protocols, and do pose a certain security hazard if misused. For instance, anybody in the world can receive undesired UDP stream from your reflector. Please deploy this software for testing purposes only!
We are not responsible for any problems this software may cause.

End user client (RTSPC)

Note: You'll need the MBone conferencing tools like vic and rat for the client to be of any use. You can download these here.

• Source: You can download the source and build it on
  • Win32 platforms (Workspace for MS Cisual C++ 6.0 provided)
  • Linux and Solaris platforms (just comment/uncomment lines in Makefile, you need Tk8.0 installed on your system)
  • other UNIX platforms (but you are on your own :)
• Binaries:
  • Win32 binary version has a nice installer which will also setup the environment
  • Linux and Solaris binaries need you to manually configure your browser to use rtspc-1.3 (or what you name it) as the helper application for the new application/rtsp-session-descr MIME-type. In Netscape, this is done in "Edit->Preferances->Navigator->Applications" meny. Choose "New Application" and enter application/rtsp-session-descr as MIME-type, rtsp as file extension, and your_dir/rtspc1.3 %s as helper application.

• SAPListener (Session announcement collector): download java tar.gz-file or zip-file which contains source, classes and documentation.
• Reflector: download
• RTSP server: (Linux only) download

Known issues

• Reflector has limited security features. The system is made for test purposes only. Please be careful when deploying the system!
• "Internal Server Error" message on your browser means that parts of the system are not running. Please send me a note and I will restart these! This should not occur frequently now.
• RTSPC is sometimes started with some garbage caracters after the URL. You'll have to remove these manually before you press the 'Connect' button. Normally, URLs are of "rtsp://host:port/file.sdp" format, so remove all characters after ".sdp".
• At Win32 with Internet Explorer, RTSPC may collide with plug-ins for QuickTime and/or Real Player, if installed (Netscape recommended). However, it is not recorded that RTSPC made any harm to other software installations!

Last updated December 14, 2000 by Guy Kværnberg.