Инструкции По Установке для 3com S7906E

 

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For devices that support both drop-unknown and igmp-snooping drop-unknown commands at 

the same time, the configuration made in IGMP snooping view and the configuration made in VLAN 

view are mutually exclusive. Namely, after this function is enabled in IGMP snooping view, it cannot 

be enabled or disabled in VLAN view, and vice versa.  

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Configurations made in IGMP snooping view are effective for all VLANs, while configurations made 

in VLAN view are effective only for ports belonging to the current VLAN.  

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If the function of dropping multicast packets is globally enabled in IGMP snooping view, multicast 

packets sent to IGMP snooping-enabled VLANs are all dropped. The multicast packets mentioned 

here include both multicast data packets and protocol packets, such as PIM, OSPF, and VRRP 

messages.  

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After the function of dropping unknown multicast data packets is enabled in VLAN view, the switch 

forwards unknown multicast data packets to its router ports, if any, instead of flooding them in the 

VLAN. Otherwise, if no router ports exist, the switch drops these multicast data packets. Currently, 

the S7900E supports processing unknown multicast data packets destined for up to 2000 unknown 

multicast addresses at a time. The switch floods excessive unknown multicast data packets 

directly.  

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The S7900E supports the function of dropping unknown multicast data packets configuring in up to 

500 VLANs. 

 

When a Layer 2 device receives an IGMP report from a multicast group member, the device forwards 

the message to the Layer 3 device directly connected with it. Thus, when multiple members of a 

multicast group are attached to the Layer 2 device, the Layer 3 device directly connected with it will 

receive duplicate IGMP reports from these members.  

With the IGMP report suppression function enabled, within each query cycle, the Layer 2 device 

forwards only the first IGMP report per multicast group to the Layer 3 device and will not forward the 

subsequent IGMP reports from the same multicast group to the Layer 3 device. This helps reduce the 

number of packets being transmitted over the network.  

Follow these steps to configure IGMP report suppression:  

Enter system view 

system-view 

— 

Enter IGMP snooping view 

igmp-snooping 

— 

Enable IGMP report 
suppression  

Optional 

Enabled by default