what is the reason for ISIS using the multicast MAC address in a LAN ?

[wlsj]

the layer 2 switch can not distinguish the multicast and broadcast,the OSPF ，EIGRP and RIPv2 also use the multicast address，but IGMP snooping can not know who need receiving the multicast data

[ruwhite]

EIGRP, RIPv2, IS-IS, and OSPF all use different layer 3 multicast addresses, so they don't overlap. As for IGMP snooping, how would IGMP know which devices need to receive these multicasts, anyway--there's no IGMP join involved in routing protocol neighbor formation, so I don't know how snooping would relate?

:-)

Russ