Operation and features


Multicast filtering is not supported on switches J9779A, J9780A, J9782A and J9783A.

In a network where IP multicast traffic is transmitted for multimedia applications, you can use a switch to reduce unnecessary per-port bandwidth usage by configuring IGMP (Internet Group Management Protocol) controls. In the factory default state (IGMP disabled), the switch floods all IP multicast traffic it receives on a given VLAN through all ports on that VLAN, except the port on which it received the traffic. This can cause significant and unnecessary bandwidth use in networks employing IP multicast traffic. With IGMP, ports can detect IGMP queries, report packets and manage IP switch multicast traffic.

IGMP is useful in multimedia applications such as LAN TV, desktop conferencing and collaborative computing that have multipoint communication (communication from one-to-many or many-to-many hosts). In such multipoint applications, IGMP is configured on the hosts and multicast traffic is generated by one or more servers (inside or outside the local network). Switches in the network that support IGMP can then be configured to direct the multicast traffic to only the ports where needed. If multiple VLANs are configured, you can configure IGMP by VLAN.

Enabling IGMP allows detection of IGMP queries and report packets to manage IP multicast traffic through the switch. If no other querier is detected, the switch then also functions as the querier. To disable the querier feature, use the IGMP configuration MIB (see "Configuring the querier function" in CLI: Configuring and displaying IGMP).


IGMP configuration on the switch operates at the VLAN context level. If you are not using VLANs, then configure IGMP in VLAN 1 (the default VLAN) context.