Broadcast on a switch?

The problem is we are doing parallel scientic computation on a cluster
we build on our own which is running linux. All the nodes are connected
to a Gigabit switch. The work is both CPU and communication intensive.

The question is how is broadcast actually done when the masternode tries
to broadcast data to all the other nodes? I am not a computer scientist
but I kind of know that on a hub any message is broadcast on the same
network and everybody could get it. While for my understanding, for
switch, there is no way do such kind of broadcasting. So although in
most cases, a switch is suprior to a hub but if what I need is to
broadcast large amout of data quickly through the local network, maybe
switch is not as good as a hub. Is that right?

If this is true, another question arises: how can we improve the
broadcasting on a switch? I searched on goole and found somebody
mentioned VLAN but have no idea of what it is. Could you give me any advice?

Thanks.

On Thu, 09 Oct 2003 14:04:01 -0400, Shi Jin wrote:

 >The problem is we are doing parallel scientic computation on a cluster
 >we build on our own which is running linux. All the nodes are connected
 >to a Gigabit switch. The work is both CPU and communication intensive.
 >
 >The question is how is broadcast actually done when the masternode tries
 >to broadcast data to all the other nodes? I am not a computer scientist
 >but I kind of know that on a hub any message is broadcast on the same
 >network and everybody could get it. While for my understanding, for
 >switch, there is no way do such kind of broadcasting. So although in
 >most cases, a switch is suprior to a hub but if what I need is to
 >broadcast large amout of data quickly through the local network, maybe
 >switch is not as good as a hub. Is that right?
 >
 >If this is true, another question arises: how can we improve the
 >broadcasting on a switch? I searched on goole and found somebody
 >mentioned VLAN but have no idea of what it is. Could you give me any advice?
 >
 >Thanks.

Are multicast packets bound to a specific port? If so a switch ought to be
able to recognize and rebroadcast such input packets through all ports...