3com 3.01.01 Manuale Utente

C

HAPTER

 6: M

ULTICAST

 P

ROTOCOL

To implement IGMP Snooping on the switch, first enable it. The switch is 
connected with the router through the router port, and with user PC through the 
non-router ports. 

Figure 6   IGMP Snooping Configuration Network

1 Display the status of GMRP.

<SW8800>display gmrp status

2 Display the current status of IGMP Snooping when GMRP is disabled. 

<SW8800>display igmp-snooping configuration

3 Enable IGMP Snooping if it is disabled. 

[SW8800]igmp-snooping enable

If the multicast function cannot be implemented on the switch, check for the 
following conditions and use the accompanying troubleshooting procedure:

1 IGMP Snooping is disabled. 

■

Input the display current-configuration command to display the status of 
IGMP Snooping. 

■

If the switch disabled IGMP Snooping, you can input igmp-snooping enable 
in the system view to enable IGMP Snooping.

2 Multicast forwarding table set up by IGMP Snooping is wrong. 

■

Input the display igmp-snooping group command to see if the multicast 
group is the expected one. 

■

Verify that the source IP address is correct for each multicast stream. 

3 Multicast forwarding table set up on the bottom layer is wrong. 

■

Enable IGMP Snooping group in user view and then input the display 
igmp-snooping group command to check if MAC multicast forwarding table 
in the bottom layer and that created by IGMP Snooping is consistent. You may 
also input the display mac vlan command in all views to check if MAC 
multicast forwarding table under vlanid in the bottom layer and that created by 
IGMP Snooping is consistent.

Internet

A router running
IGMP

An Ethernet switch
running IGMP 
snooping

IGMP packets

IGMP packets