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FTOS Configuration Guide for the C-Series - Force10 Networks

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Viewing IGMP Groups<br />

View both learned and statically configured IGMP groups using <strong>the</strong> command show ip igmp groups from<br />

EXEC Privilege mode.<br />

Figure 416 Viewing Static and Learned IGMP Groups<br />

<strong>Force10</strong>(conf-if-gi-1/0)#do sho ip igmp groups<br />

Total Number of Groups: 2<br />

IGMP Connected Group Membership<br />

Group Address Interface Uptime Expires Last Reporter<br />

224.1.1.1 GigabitE<strong>the</strong>rnet 1/0 00:00:03 Never CLI<br />

224.1.2.1 GigabitE<strong>the</strong>rnet 1/0 00:56:55 00:01:22 1.1.1.2<br />

Adjusting Timers<br />

View <strong>the</strong> current value of all IGMP timers using <strong>the</strong> command show ip igmp interface from EXEC<br />

Privilege mode, as shown in Figure 414.<br />

Adjusting Query and Response Timers<br />

The querier periodically sends a general query to discover which multicast groups are active. A group must<br />

have at least one host to be active. When a host receives a query, it does not respond immediately, but<br />

ra<strong>the</strong>r starts a delay timer. The delay time is set to a random value between 0 and <strong>the</strong> Maximum Response<br />

Time. The host sends a response when <strong>the</strong> timer expires; in version 2, if ano<strong>the</strong>r host responds be<strong>for</strong>e <strong>the</strong><br />

timer expires, <strong>the</strong> timer is nullified, and no response is sent.<br />

The Maximum Response Time is <strong>the</strong> amount of time that <strong>the</strong> querier waits <strong>for</strong> a response to a query be<strong>for</strong>e<br />

taking fur<strong>the</strong>r action. The querier advertises this value in <strong>the</strong> query (see Figure 409). Lowering this value<br />

decreases leave latency but increases response burstiness since all host membership reports must be sent<br />

be<strong>for</strong>e <strong>the</strong> Maximum Response Time expires. Inversely, increasing this value decreases burstiness at <strong>the</strong><br />

expense of leave latency.<br />

• Adjust <strong>the</strong> period between queries using <strong>the</strong> command ip igmp query-interval from INTERFACE<br />

mode.<br />

• Adjust <strong>the</strong> Maximum Response Time using <strong>the</strong> command ip igmp query-max-resp-time from<br />

INTERFACE mode.<br />

When <strong>the</strong> querier receives a leave message from a host, it sends a group-specific query to <strong>the</strong> subnet. If no<br />

response is received, it sends ano<strong>the</strong>r. The amount of time that <strong>the</strong> querier waits to receive a response to <strong>the</strong><br />

initial query be<strong>for</strong>e sending a second one is <strong>the</strong> Last Member Query Interval (LMQI). The switch waits one<br />

LMQI after <strong>the</strong> second query be<strong>for</strong>e removing <strong>the</strong> group from <strong>the</strong> state table.<br />

• Adjust <strong>the</strong> Last Member Query Interval using <strong>the</strong> command ip igmp last-member-query-interval from<br />

INTERFACE mode.<br />

590 Internet Group Management Protocol

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