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User’s Manual of SGSD-1022 / SGSD-1022P
SGSW-2840 / SGSW-2840P
207
Unknown multicast traffic is flooded to all ports in the VLAN for several seconds when first
received. If a multicast router port exists on the VLAN, the traffic will be filtered by subjecting
it to IGMP snooping. If no router port exists on the VLAN or the multicast filtering table is
already full, the switch will continue flooding the traffic into the VLAN.
IGMP Querier –
A router, or multicast-enabled switch, can periodically ask their hosts if they want to receive multicast traffic. If there is more
than one router/switch on the LAN performing IP multicasting, one of these devices is elected “querier” and assumes the
role of querying the LAN for group members. It then propagates the service requests on to any upstream multicast
switch/router to ensure that it will continue to receive the multicast service.
Multicast routers use this information, along with a multicast routing protocol such as
DVMRP or PIM, to support IP multicasting across the Internet.
Figure 4-9-1 IGMP Configuration page screenshot
The page includes the following fields:
Object Description
• IGMP Status
When enabled, the switch will monitor network traffic to determine which hosts
want to receive multicast traffic. This is also referred to as IGMP Snooping.
(Default: Enabled)
• Act as IGMP Querier
When enabled, the switch can serve as the Querier, which is responsible for
asking hosts if they want to receive multicast traffic.
This feature is not supported for IGMPv3 snooping.