----- Original Message ----- From: "matt massie" <[EMAIL PROTECTED]>
> > I'm pretty sure the catalyst switches can be set to do multicast more > > effeciently by setting 'ip cgmp' on them, though I haven't confirmed > > this. With 'ip cgmp' set on, machines can join and leave multicast > > channels as they please and the switch will only direct packets to those > > machines that need to listen to them. Normally though, the switch is > > literally just broadcasting out each and every multicast ip packet to > > every machine on the lan/vlan. I don't have direct access to the > > catalyst switches at work and I haven't gotten the admin in charge to > > make the change. So in this way if the ganglia community just had a > > quick html page with confirmed tips on switch configuration it would be > > a big help. > > http://ganglia.sourceforge.net/ganglia_docs/notes.html#NOTES-CISCO > > -matt Ok, this is good that its on the ganglia site now and presented in such a way that the reader can read through it and evaluate it for themselves. Another concern my network admin had before even enabling 'ip cgmp' was what kind of potentially negative performance impact it might have on the switch. So what I'm going to do is as steve mentioned just set up additional interfaces for each box that will essentially be administrative interfaces, for lightweight telnet and other duties to the box, maybe nfs, and have a static route for the ganglia multicast channel on each machine to go through that secondary interface. Those new interfaces will plug into a newly defined vlan on the catalyst that will have ip cgmp set on it. Presto, zero impact to the other vlans and multicast is managed efficiently on the dedicated administrative vlan as well :)
