I have a small subnet with a single switch, where some users connect with cable and the majority of the users are connecting via wireless 802.1g via a RB433 connected to the same switch.
There is not supposed to be any multicast in the network, but a user has tried to set up his own VNC streaming, and used the following command on his linux box:
vlc -vvv movie.avi --sout udp:230.1.1.1 --ttl 3
The users connected via cable don’t notice anything, but the RB433 immediately rolls over on its back and almost dies. All users connected via wireless gets pingtimes above 30000 ms, and then all disconnect from the RB433 within a minute.
When the user stops vlc, all users come back online and everything is fine again.
Can someone explain what is happening here? What is the RB433 trying to do..? All I can see in the sniffer on the RB433 are the multicast packets coming in on ether1, but I have no idea why that would cause a complete DoS..?