Operation Manual – Multicast
H3C S3100 Series Ethernet Switches
Chapter 2 IGMP Snooping Configuration
2-11
Note:
z
To prevent bursting traffic in the network or performance deterioration of the device
caused by excessive multicast groups, you can set the maximum number of
multicast groups that the switch should process.
z
When the number of multicast groups exceeds the configured limit, the switch
removes its multicast forwarding entries starting from the oldest one. In this case,
the multicast packets for the removed multicast group(s) will be flooded in the VLAN
as unknown multicast packets. As a result, non-member ports can receive multicast
packets within a period of time. To avoid this from happening, enable the function of
dropping unknown multicast packets.
2.2.7 Configuring IGMP Snooping Querier
Note:
Only the S3100-EI series support the IGMP Snooping querier feature.
In an IP multicast network running IGMP, a multicast router or Layer 3 multicast switch
is responsible for sending IGMP general queries, so that all Layer 3 multicast devices
can establish and maintain multicast forwarding entries, thus to forward multicast traffic
correctly at the network layer. This router or Layer 3 switch is called IGMP querier.
However, a Layer 2 multicast switch does not support IGMP, and therefore cannot send
general queries by default. By enabling IGMP Snooping querier on a Layer 2 switch in a
VLAN where multicast traffic needs to be Layer-2 switched only and no multicast
routers are present, the Layer 2 switch will act as a querier to send IGMP general
queries, thus allowing multicast forwarding entries to be established and maintained at
the data link layer.
You can also configure the source address, maximum response time and interval of
general queries to be sent from the IGMP Snooping querier.
Table 2-11
Configure IGMP Snooping querier
Operation
Command
Remarks
Enter system view
system-view
—
Enable IGMP Snooping
igmp-snooping enable
Required
By default, IGMP
Snooping is disabled.
Enter VLAN view
vlan vlan-id
—