In order to use the Ethernet bridging functionality, you’ll need the
userspace tools. These programs and documentation are available
at http://www.linux-foundation.org/en/Net:Bridge. The download page is
http://prdownloads.sourceforge.net/bridge.
If you still have questions, don’t hesitate to post to the mailing list
(more info http://lists.osdl.org/mailman/listinfo/bridge).
