We have multicast confiugred on campus network. Edge switches (layer2) have uplinks to distribution switches (layer3 cat6506). The distribution switch have ip pim configured under vlan interface and edge switch configured with igmp snooping. Recently, observed a large amount of IGMP join and leave message from edge switches. The source looks like from all edge switches and destination multicast IP is not fixed. The large amount of igmp messages cause our egde switches and distribution switches cpu surge to 99%. After take out the ip pim configuration from the vlan interface, the cpu will back to normal. The igmp rate limiting and access group doesn't work as the destiniation multicast IP is not fixed. Any suggestion to prevent this kind of traffic?