Management Guide - Kamery IP

3Configuring the SwitchStatic IGMP Host Interface – For multicast applications that you need to controlmore carefully, you can manually assign a multicast service to specific interfaces onthe switch (page 3-295).Configuring IGMP Snooping and Query ParametersYou can configure the switch to forward multicast traffic intelligently. Based on theIGMP query and report messages, the switch forwards traffic only to the ports thatrequest multicast traffic. This prevents the switch from broadcasting the traffic to allports and possibly disrupting network performance.Command Usage• IGMP Snooping – This switch can passively snoop on IGMP Query and Reportpackets transferred between IP multicast routers/switches and IP multicast hostgroups to identify the IP multicast group members. It simply monitors the IGMPpackets passing through it, picks out the group registration information, andconfigures the multicast filters accordingly.Note: Unknown multicast traffic is flooded to all ports in the VLAN for several secondswhen first received. If a multicast router port exists on the VLAN, the traffic will befiltered by subjecting it to IGMP snooping. If no router port exists on the VLAN orthe multicast filtering table is already full, the switch will continue flooding the trafficinto the VLAN.• IGMP Querier – A router, or multicast-enabled switch, can periodically ask theirhosts if they want to receive multicast traffic. If there is more than one router/switchon 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 propagatesthe service requests on to any upstream multicast switch/router to ensure that it willcontinue to receive the multicast service.Note: Multicast routers use this information from IGMP snooping and query reports,along with a multicast routing protocol such as DVMRP or PIM, to support IPmulticasting across the Internet.• IGMP Leave Proxy – This function is only effective if IGMP snooping is enabled.IGMP leave proxy suppresses all unnecessary IGMP leave messages so that thenon-querier switch forwards an IGMP leave packet only when the last dynamicmember port leaves a multicast group.The leave-proxy feature does not function when a switch is set as the querier.When the switch a non-queier, the receiving port is not the last dynamic memberport in the group, the receiving port is not a router port, and no IGMPv1 memberport exists in the group, the switch will generate and send a GS-query to themember port which received the leave message, and then start the last memberquery timer for that port.When the conditions in the preceding item all apply, except that the receiving portis a router port, then the switch will not send a GS-query, but will immediately startthe last member query timer for that port.3-288