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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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IGMP Snooping<br />

IGMP Snooping versions 1 and 2 are supported on plat<strong>for</strong>ms: c e s<br />

IGMP Snooping version 3 is supported only on plat<strong>for</strong>m e<br />

Multicast packets are addressed with multicast MAC addresses, which represent a group of devices, ra<strong>the</strong>r<br />

than one unique device. Switches <strong>for</strong>ward multicast frames out of all ports in a VLAN by default, even<br />

though <strong>the</strong>re may be only some interested hosts, which is a waste of bandwidth. IGMP Snooping enables<br />

switches to use in<strong>for</strong>mation in IGMP packets to generate a <strong>for</strong>warding table that associates ports with<br />

multicast groups so that when <strong>the</strong>y receive multicast frames, <strong>the</strong>y can <strong>for</strong>ward <strong>the</strong>m only to interested<br />

receivers.<br />

IGMP Snooping Implementation In<strong>for</strong>mation<br />

• IGMP Snooping on <strong>FTOS</strong> uses IP multicast addresses not MAC addresses.<br />

• IGMP snooping is not supported on stacked VLANs, or with stacking on <strong>the</strong> S-<strong>Series</strong>.<br />

• IGMP snooping reacts to STP and MSTP topology changes by sending a general query on <strong>the</strong> interface<br />

that transitions to <strong>the</strong> <strong>for</strong>warding state.<br />

Configuring IGMP Snooping<br />

Configuring IGMP Snooping is a one-step process. That is, enable it on a switch using <strong>the</strong> command ip<br />

igmp snooping enable from CONFIGURATION mode. View <strong>the</strong> configuration using <strong>the</strong> command show<br />

running-config from CONFIGURATION mode, as shown in Figure 417. You can disable snooping on <strong>for</strong><br />

a VLAN using <strong>the</strong> command no ip igmp snooping from INTERFACE VLAN mode.<br />

Figure 417 Enabling IGMP Snooping<br />

<strong>Force10</strong>(conf)#ip igmp snooping enable<br />

<strong>Force10</strong>(conf)#do show running-config igmp<br />

ip igmp snooping enable<br />

<strong>Force10</strong>(conf)#<br />

Related <strong>Configuration</strong> Tasks<br />

• Enabling IGMP Immediate-leave on page 594<br />

• Disabling Multicast Flooding on page 594<br />

• Specifying a Port as Connected to a Multicast Router on page 594<br />

• Configuring <strong>the</strong> Switch as Querier on page 594<br />

<strong>FTOS</strong> <strong>Configuration</strong> <strong>Guide</strong>, version 7.7.1.0 593

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