Cisco 2950G 24 Software Configuration Guide - Page 396
Setting the Snooping Method, Snooping on IGMP queries, Protocol Independent Multicast PIM packets
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Configuring IGMP Snooping Chapter 17 Configuring IGMP Snooping and MVR Beginning in privileged EXEC mode, follow these steps to globally enable IGMP snooping on the switch: Step 1 Step 2 Step 3 Step 4 Command configure terminal ip igmp snooping end copy running-config startup-config Purpose Enter global configuration mode. Globally enable IGMP snooping in all existing VLAN interfaces. Return to privileged EXEC mode. (Optional) Save your entries in the configuration file. To globally disable IGMP snooping on all VLAN interfaces, use the no ip igmp snooping global configuration command. Beginning in privileged EXEC mode, follow these steps to enable IGMP snooping on a VLAN interface: Step 1 Step 2 Step 3 Step 4 Command configure terminal ip igmp snooping vlan vlan-id end copy running-config startup-config Purpose Enter global configuration mode. Enable IGMP snooping on the VLAN interface. Return to privileged EXEC mode. (Optional) Save your entries in the configuration file. To disable IGMP snooping on a VLAN interface, use the no ip igmp snooping vlan vlan-id global configuration command for the specified VLAN number. Setting the Snooping Method Multicast-capable router ports are added to the forwarding table for every Layer 2 multicast entry. The switch learns of such ports through one of these methods: • Snooping on IGMP queries, Protocol Independent Multicast (PIM) packets, and Distance Vector Multicast Routing Protocol (DVMRP) packets • Listening to Cisco Group Management Protocol (CGMP) packets from other routers • Statically connecting to a multicast router port with the ip igmp snooping mrouter global configuration command You can configure the switch either to snoop on IGMP queries and PIM/DVMRP packets or to listen to CGMP self-join or proxy-join packets. By default, the switch snoops on PIM/DVMRP packets on all VLANs. To learn of multicast router ports through only CGMP packets, use the ip igmp snooping vlan vlan-id mrouter learn cgmp global configuration command. When this command is entered, the router listens to only CGMP self-join and CGMP proxy-join packets and no other CGMP packets. To learn of multicast router ports through only PIM-DVMRP packets, use the ip igmp snooping vlan vlan-id mrouter learn pim-dvmrp global configuration command. 17-6 Catalyst 2950 Desktop Switch Software Configuration Guide 78-14982-01
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