No, just normal troubleshooting techniques. Could not find a way to drop a pc for an active multicast

what network switches do you use? Do you have igmp or cgmp enabled?

I am running fog on a ubuntu server. I have multicast setup and running, but in certain areas of my buildings, the multicast session are very slow.
(in most areas, I can image 20-50 machines at about 500mib, a slow connection ranges between 50-60mib)

I am sure it is a bad cable, or a bad switch, but I am wondering what is the quickest way to troubleshoot? Does fog have any capability to show a bad connection to a particular machine? Is there a way to drop machines from an active multicast session (in order to see if speed increases significantly)
thanks