[AG-TECH] rcbridge 1.0.0 (unicast<->multicast bridge) is out

Markus Buchhorn Markus.Buchhorn at anu.edu.au
Fri Nov 28 00:46:54 CST 2003

Hi All

We're looking for some enthusiastic (and friendly!) beta testers for rcbridge, and hoped we could find some on these lists :-)

Yet another unicast/multicast bridge? Yes! But why?

rcbridge is an extremely simple bridge between the two worlds. The main distinguishing features of rcbridge over other bridges are

 - it has a remote-control interface (hence R.C. bridge)
 - it supports user-controlled stream selection, dynamically.
 - it supports any number (ymmv) of addresses and destinations, dynamically.

The remote control is implemented through a micro-webserver embedded in rcbridge. The idea is that the hosting site (with excellent multicast connectivity) has to only install the rcbridge and do some minor configuration (ACLs, ttl's, port selection, ...) - and nothing else. No more configuring group-specific bridges on demand every other day, or forcing users into a narrow set of addresses.

When you (the client) point a web browser (or other http client) at the rcbridge server, you get allocated your own "tunnel", and you get to configure it as you want. You can have multiple tunnels to you if you want.

For rtp-based streams, rcbridge allows you to selectively forward any/all/none of them, and change that selection in real time. This is great for the bandwidth challenged (as if not having multicast wasn't bad enough!). We're using it (or going to be) for AccessGrid session delivery to home, to wireless devices, to PDAs/other small-display systems, etc. 

It also automagically forwards rtcp in parallel.

rcbridge 1.0.0 (yes, two zeroes :-) ) is now available for download. You'll need Java 1.4 installed on your multicast enabled box.


and follow the bouncing ball. 

If you want to have your tunneled multicast traffic delivered to more than one machine, have a look at:


which is the associated very simple (command-line, java) client, which allows for local remulticasting if needed. You don't need it, to use rcbridge, but it might help in your particular situation.

Please try it out and report any bugs/issues to rcbridge at if.anu.edu.au

There are many things we still have planned for it, and some things we don't like about it yet. The tunneling is a pure payload shuffle, and all that that implies. A real tunneling implementation has some benefits (e2e transparency), but also some drawbacks (client complexity). We're aiming to implement that flexibly. We'll probably move away from Java in 2.x, if Java doesn't appeal to you. There's a list of things on the above web page, and more in our heads.

We're looking for feedback, bug reports, suggestions, criticisms, etc. We want to know how people use it, if/how it helps (or not) and how we can make it better. (This also applies to the documentation.)


Markus Buchhorn, ANU Internet Futures Project,      | Ph: +61 2 61258810
Markus.Buchhorn at anu.edu.au, mail: Bldg #108 - CS&IT |Fax: +61 2 61259805
Australian National University, Canberra 0200, Aust.|Mob: 0417 281429

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