We are experiencing an issue that maybe this forum can shed some light.
Every morning for about 30 minutes my users complain of a network slowdown. We just installed a 6500 Cisco core Switch about two months ago and this is when the issue "started". When I sniffed a port of one of the users, I see a lot of this traffic during that timeframe:
This indeed appears to be a multicast of some sort - the FF00::/8 prefix is an IPv6 multicast prefix. I do not recognize the multicast address, though. Do you have an option of capturing the traffic via Wireshark and post the capture file here? We could perhaps find out what kind of multicast stream is being sent here.