3com 5500-ei pwr Installation Instruction

 

5 

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If the multicast MAC address entry to be created already exists, the system gives you a prompt. 

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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.  

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You cannot configure a multicast MAC address starting with 01005e on a device with XRN Fabric 

enabled.  

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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. 

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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. 

 

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: 

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. 

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.  

Trace a multicast path 

mtracert source-address 
[ [ last-hop-router-address ] 
group-address ] 

Required 

Available in any view 

 

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: 

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Each multicast routing protocol has its own multicast routing table, such as PIM routing table. 

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The information of different multicast routing protocols forms a general multicast routing table.