When a receiver connected on a Cluster Client Edge Port (CCEP) sends a membership report to join group G, the election of the designated forwarder (DF) for the CCEP and MGID prevents duplication of multicast data packets destined to group G on CCEP and on the peer link.
DF election is always honored for programming receivers on CCEP in the multicast group ID (MGID). However, the path given by DF election may not be optimal, because it might direct the multicast data traffic originating at one peer switch to a receiver on CCEP over the peer link, even though (*,G) membership does not include the Cluster Edge Port (CEP) on the peer switch that does not host the source.
When a group is learned over member VLANs, the DF for the IGMP route is elected by hashing on the IVID parameter of the member VLAN, Source-IP, and Group-IP.
Receivers connected through CCEP
Interchassis link (ICL), if its multichassis trunk (MCT) peer has receivers connected through CEP
Receivers connected through local CEP
ICL to redirect the multicast stream to the DF of the stream
Receivers connected through CEP