6-9z A port can belong to multiple VLANs, you can configure only one ACL rule per VLAN on a port.z If no ACL rule is configured, all the multicast groups will be filtered.z Since most devices broadcast unknown multicast packets by default, this function is often usedtogether with the function of dropping unknown multicast packets to prevent multicast streams frombeing broadcast as unknown multicast packets to a port blocked by this function.z The configuration performed in system view takes effect on all ports of the switch if no VLAN isspecified; if one or more VLANs are specified, the configuration takes effect on all ports in thespecified VLAN(s).z The configuration performed in Ethernet port view takes effect on the port no matter which VLAN itbelongs to if no VLAN is specified; if one or more VLANs are specified, the configuration takeseffect on the port only if the port belongs to the specified VLAN(s).Configuring the Maximum Number of Multicast Groups on a PortBy configuring the maximum number of multicast groups that can be joined on a port, you can limit thenumber of multicast programs on-demand available to users, thus to regulate traffic on the port.Follow these steps to configure the maximum number of multicast groups on a port:To do... Use the command... RemarksEnter system view system-view —Enter Ethernet port view interface interface-typeinterface-number —Limit the number of multicastgroups on a portigmp-snooping group-limit limit[ vlan vlan-list[ overflow-replace ] ]RequiredThe maximum number of multicastgroups on a port is 256 by default.z To prevent bursting traffic in the network or performance deterioration of the device caused byexcessive multicast groups, you can set the maximum number of multicast groups that the switchshould process.z When the number of multicast groups exceeds the configured limit, the switch removes itsmulticast forwarding entries starting from the oldest one. In this case, the multicast packets for theremoved 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 fromhappening, enable the function of dropping unknown multicast packets.z If an Ethernet port is a static member port for a multicast group, the configuration of the maximumnumber of multicast groups that can be joined does not take effect on the port.
