All things related to multicast

[Joe Pautler <>]

Dan Pritts wrote:           (written on 09/24/04 at 11:33)
]
]The only big issue I have had with multicast with these switches is when
]you have a local multicast source but no local listener on that group.
]The switch defaults to flooding all ports with that group when this
]happens.

]I'd be interested in knowing folks' experiences with other switch lines.
]In particular, do any of them have a knob to tweak to disable "flood
]by default" for IP multicast traffic with no declared listeners?

We have seen the same behavior with Nortel Baystack 450 switches.
Normally it's not a big problem, because the sender tends to join
their own group.  As Alan pointed out, some applications give
the user the choice of whether or not to join their own group.

But like you said, when the flooding does occur, it basically
serves as a DOS attack against the other users connected to 
the switch.

-Joe Pautler
 University at Buffalo