Cisco 2950G 24 Software Configuration Guide - Page 395
Configuring IGMP Snooping, Default IGMP Snooping Configuration, Enabling or Disabling IGMP Snooping
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Chapter 17 Configuring IGMP Snooping and MVR Configuring IGMP Snooping Note You should only use the Immediate-Leave processing feature on VLANs where a single host is connected to each port. If Immediate Leave is enabled in VLANs where more than one host is connected to a port, some hosts might be inadvertently dropped. Immediate Leave is supported with only IGMP version 2 hosts. Configuring IGMP Snooping IGMP snooping allows switches to examine IGMP packets and make forwarding decisions based on their content. These sections describe how to configure IGMP snooping: • Default IGMP Snooping Configuration, page 17-5 • Enabling or Disabling IGMP Snooping, page 17-5 • Setting the Snooping Method, page 17-6 • Configuring a Multicast Router Port, page 17-7 • Configuring a Host Statically to Join a Group, page 17-8 • Enabling IGMP Immediate-Leave Processing, page 17-9 • Disabling IP Multicast-Source-Only Learning, page 17-9 Default IGMP Snooping Configuration Table 17-3 shows the default IGMP snooping configuration. Table 17-3 Default IGMP Snooping Configuration Feature IGMP snooping Multicast routers Multicast router learning (snooping) method IGMP snooping Immediate Leave Static groups IP multicast-source-only learning Default Setting Enabled globally and per VLAN None configured PIM-DVMRP Disabled None configured Enabled Enabling or Disabling IGMP Snooping By default, IGMP snooping is globally enabled on the switch. When globally enabled or disabled, it is also enabled or disabled in all existing VLAN interfaces. IGMP snooping is by default enabled on all VLANs, but can be enabled and disabled on a per-VLAN basis. Global IGMP snooping overrides the VLAN IGMP snooping. If global snooping is disabled, you cannot enable VLAN snooping. If global snooping is enabled, you can enable or disable VLAN snooping. 78-14982-01 Catalyst 2950 Desktop Switch Software Configuration Guide 17-5
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