Configuring the Switch3-1403Configuring 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.• 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, along with a multicast routing protocol suchas DVMRP or PIM, to support IP multicasting across the Internet.Command Attributes• IGMP Status — When enabled, the switch will monitor network traffic to determinewhich hosts want to receive multicast traffic. This is also referred to as IGMPSnooping. (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.(Default: Enabled)• IGMP Query Count — Sets the maximum number of queries issued for whichthere has been no response before the switch takes action to drop a client from themulticast group. (Range: 2-10, Default: 2)• IGMP Query Interval — Sets the frequency at which the switch sends IGMPhost-query messages. (Range: 60-125 seconds, Default: 125)• IGMP Report Delay — Sets the time between receiving an IGMP Report for an IPmulticast address on a port before the switch sends an IGMP Query out of that portand removes the entry from its list. (Range: 5-30 seconds, Default: 10)• IGMP Query Timeout — The time the switch waits after the previous querier stopsbefore it considers the router port (i.e., the interface which had been receivingquery packets) to have expired. (Range: 300-500 seconds, Default: 300)• IGMP Version — Sets the protocol version for compatibility with other devices onthe network. (Range: 1-2; Default: 2)Notes: 1. All systems on the subnet must support the same version.2. Some attributes are only enabled for IGMPv2, including IGMP Report Delayand IGMP Query Timeout.
