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FTOS Configuration Guide for the C-Series - Force10 Networks

FTOS Configuration Guide for the C-Series - Force10 Networks

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• When enabled, IGMP snooping Querier starts after one query interval in case no IGMP general query<br />

(with IP SA lower than its VLAN IP address) is received on any of its VLAN members.<br />

Adjusting <strong>the</strong> Last Member Query Interval<br />

When <strong>the</strong> querier receives a leave message from a receiver, it sends a group-specific query out of <strong>the</strong> ports<br />

specified in <strong>the</strong> <strong>for</strong>warding table. If no response is received, it sends ano<strong>the</strong>r. The amount of time that <strong>the</strong><br />

querier waits to receive a response to <strong>the</strong> initial query be<strong>for</strong>e sending a second one is <strong>the</strong> Last Member<br />

Query Interval (LMQI). The switch waits one LMQI after <strong>the</strong> second query be<strong>for</strong>e removing <strong>the</strong><br />

group-port entry from <strong>the</strong> <strong>for</strong>warding table.<br />

Adjust <strong>the</strong> Last Member Query Interval using <strong>the</strong> command ip igmp snooping<br />

last-member-query-interval from INTERFACE VLAN mode.<br />

Fast Convergence after MSTP Topology Changes<br />

When a port transitions to <strong>the</strong> Forwarding state as a result of an STP or MSTP topology change, <strong>FTOS</strong><br />

sends a general query out of all ports except <strong>the</strong> multicast router ports. The host sends a response to <strong>the</strong><br />

general query and <strong>the</strong> <strong>for</strong>warding database is updated without having to wait <strong>for</strong> <strong>the</strong> query interval to<br />

expire.<br />

When an IGMP snooping switch is not acting as a Querier it sends out <strong>the</strong> general query, in response to <strong>the</strong><br />

MSTP triggered link-layer topology change, with <strong>the</strong> source IP address of 0.0.0.0 to avoid triggering<br />

Querier election.<br />

Designating a Multicast Router Interface<br />

You can designate an interface as a multicast router interface with <strong>the</strong> command ip igmp snooping<br />

mrouter interface. <strong>FTOS</strong> also has <strong>the</strong> capability of listening in on <strong>the</strong> incoming IGMP General Queries<br />

and designate those interfaces as <strong>the</strong> multicast router interface when <strong>the</strong> frames have a non-zero IP source<br />

address. All IGMP control packets and IP multicast data traffic is <strong>for</strong>warded to <strong>the</strong> interfaces designated as<br />

multicast router interface.<br />

Using PIM-SSM with IGMP version 2 Hosts<br />

PIM-SSM requires receivers that support IGMP version 3. You can employ PIM-SSM even when receivers<br />

support only IGMP version 1 or version 2 by translating (*,G) memberships to (S,G) memberships.<br />

Translate (*,G) memberships to (S,G) memberships using <strong>the</strong> command ip igmp ssm-map from<br />

INTERFACE mode.<br />

<strong>FTOS</strong> <strong>Configuration</strong> <strong>Guide</strong>, version 7.7.1.0 595

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