3Com 8807 Configuration Manual page 424

424 C 39: IGMP S
HAPTER
Configuring Unknown
Multicast Packets not
Broadcasted within a
VLAN
Configuring the Filtering
Rule of Multicast Groups
C
NOOPING ONFIGURATION
By default, the aging time of the multicast member is 260 seconds.
This configuration task is to enable/disable the function of not broadcasting
unknown multicast packets within a VLAN. If this function is disabled but IGMP
snooping enabled on VLAN, multicast packets are broadcasted on within the
VLAN when the destination broadcast group has no member ports. When this
function is enabled, however, multicast packets are only forwarded to the router
port, but not broadcasted within the VLAN if no member port exists. In addition,
since the router sends regularly IGMP Query and PIM Hello packets, the switch can
identify which ports are router ports. If there is no member port or router port, the
packets will be directly dropped, instead of being forwarded.
c
CAUTION: If IGMP snooping is not enabled on the VLAN (nor Layer 3 multicast),
unknown multicast packets are broadcasted within the VLAN no matter whether
this function is enabled or not. Therefore, to disable unknown multicast packets
from flooding within a VLAN, you must enable igmp-snooping in this VLAN and
carry out the igmp-snooping nonflooding-enable command.
Perform the following configuration in system view.
Table 415 Globally enable/disable multicast packets not broadcasted within a VLAN
Operation
Enable multicast packets not to be
broadcasted within a VLAN
Disable multicast packets not to be
broadcasted within a VLAN
By default, unknown multicast packets are broadcasted within the VLAN.
On the IGMP snooping-enabled switch, you can configure ACL rules whether the
specified multicast group can be joined to a VLAN or not. This feature filters every
received IGMP join packet. According to the destination group address of the
packets and the ACL rule bound to the VLAN, the switch determines whether to
discard the packets or let them pass.
By setting the filtering rule of multicast groups in the VLAN, you can control access
to IP multicast groups. You can only configure one ACL rule for each VLAN, and
the new configured rule will replace the old one.
Perform the following configuration in system view.
Table 416 Configure the filtering rule of multicast group
Operation
Set the filtering rule of multicast groups in the
specified VLAN
Cancel the filtering rule of multicast groups in
the specified VLAN
By default, no filtering rule is set for a VLAN. In this case, a host can be joined to
any multicast group.
Command
igmp-snooping nonflooding-enable
undo igmp-snooping nonflooding-enable
Command
igmp-snooping group-policy acl-number
undo igmp-snooping group-policy