H3C Technologies H3C S3600 Series Switches - Manual (Page 392)

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z If the multicast MAC address entry to be created already exists, the system gives you a prompt.
z If you want to add a port to a multicast MAC address entry created through the mac-address
multicast command, you need to remove the entry first, create this entry again, and then add the
specified port to the forwarding ports of this entry.
z You cannot configure a multicast MAC address starting with 01005e on a device with IRF Fabric
enabled.
z You cannot enable link aggregation on a port on which you have configured a multicast MAC
address, and you cannot configure a multicast MAC address on an aggregation port.
z You cannot configure a multicast MAC address starting with 01005e in an
IGMP-Snooping-enabled VLAN. You can do that if IGMP Snooping is not enabled in the VLAN.
Configuring Dropping Unknown Multicast Packets
Generally, if the multicast address of the multicast packet received on the switch is not registered on the
local switch, the packet will be flooded in the VLAN which the multicast packet belongs to. When the
function of dropping unknown multicast packets is enabled, the switch will drop any multicast packets
whose multicast address is not registered. Thus, the bandwidth is saved and the processing efficiency
of the system is improved.
Follow these steps to configure dropping unknown multicast packet:
To do... Use the command... Remarks
Enter system view system-view —
Configure dropping unknown
multicast packets unknown-multicast drop
enable
Required
By default, the function of
dropping unknown multicast
packets is disabled.
Tracing a Multicast Path
You can run the mtracert command to trace the path down which the multicast traffic flows from a given
first-hop router to the last-hop router.
To do… Use the command… Remarks
Trace a multicast path
mtracert source-address
[ [ last-hop-router-address ]
group-address ]
Required
Available in any view
Displaying and Maintaining Common Multicast Configuration
The information about the multicast forwarding table is mainly used for debugging. Generally, you can
get the required information by checking the core multicast routing table.
Three kinds of tables affect multicast data transmission. Their correlations are as follows: