1-16
Configuring multicast source port filtering on a port or a group of ports
Follow these steps to configure multicast source port filtering on a port or a group of ports:
To do...
Use the command...
Remarks
Enter system view
system-view
—
interface interface-type
interface-number
Enter Ethernet port view
or port group view
port-group
manual port-group-name
Required
Use either approach
Enable multicast source
port filtering
igmp-snooping source-deny
Required
Disabled by default
3Com Switch 4800G, when enabled to filter IPv4 multicast data based on the source ports, are
automatically enabled to filter IPv6 multicast data based on the source ports.
Configuring the Function of Dropping Unknown Multicast Data
Unknown multicast data refers to multicast data for which no entries exist in the IGMP Snooping
forwarding table. When receiving such multicast traffic, the switch floods it in the VLAN, incurring
network bandwidth waste and low forwarding efficiency.
With the function of dropping unknown multicast data enabled, the switch forwards unknown multicast
data to its router ports instead of flooding it in the VLAN. If no router ports exist, the switch drops the
unknown multicast data..
Follow these steps to configure the function of dropping unknown multicast data in a VLAN:
To do...
Use the command...
Remarks
Enter system view
system-view
—
Enter VLAN view
vlan vlan-id
—
Enable the function of dropping
unknown multicast data
igmp-snooping
drop-unknown
Required
Disabled by default
Configuring IGMP Report Suppression
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.