SMC Networks SMC6724L3 manual 146

CONFIGURING THE SWITCH

•Max Query Response Time – Configures the maximum response time advertised in IGMP queries. (Range: 0-25 seconds; Default: 10 seconds)

-The switch must be using IGMPv2 for this command to take effect.

-This command defines how long any responder (i.e., client or router) still in the group has to respond to a query message before the router deletes the group.

-By varying the Maximum Query Response Time, you can tune the burstiness of IGMP messages passed on the subnet; where larger values make the traffic less bursty, as host responses are spread out over a larger interval.

-The number of seconds represented by the maximum response interval must be less than the Query Interval.

•Query Interval – Configures the frequency at which host query messages are sent. (Range: 1-255; Default: 125 seconds)

-Multicast routers send host query messages to determine the interfaces that are connected to downstream hosts requesting a specific multicast service. Only the designated multicast router for a subnet sends host query messages, which are addressed to the multicast address 224.0.0.1.

-For IGMP Version 1, the designated router is elected according to the multicast routing protocol that runs on the LAN. But for IGMP Version 2, the designated querier is the lowest IP-addressed multicast router on the subnet.

•Robustness Variable – Specifies the robustness (i.e., expected packet loss) for this interface. The robustness value is used in calculating the appropriate range for other IGMP variables, such as the Group Membership Interval (Last Member Query Interval), as well as the Other Querier Present Interval, and the Startup Query Count (RFC 2236). (Range: 1-255; Default: 2)

•Version – Configures the IGMP version used on an interface. (Options: Version 1 or 2; Default: Version 2)

-All routers on the subnet must support the same version. However, the multicast hosts on the subnet may support either IGMP version 1 or 2.

-The switch must be set to version 2 to enable the Max Query Response Time.

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