Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 454

If you enable IGMP snooping on a VLT unit, IGMP snooping dynamically learned groups and multicast router ports are made to learn on the peer by explicitly tunneling the received IGMP control packets. IGMP Snooping Implementation Information • IGMP snooping uses IP multicast addresses not MAC addresses. • IGMP snooping reacts to spanning tree protocol (STP) and multiple spanning tree protocol (MSTP) topology changes by sending a general query on the interface that transitions to the forwarding state. • If IGMP snooping is enabled on a PIM-enabled VLAN interface, data packets using the router as an Layer 2 hop may be dropped. To avoid this scenario, Dell Networking recommends that users enable IGMP snooping on server-facing end-point VLANs only. Configuring IGMP Snooping Configuring IGMP snooping is a one-step process. To enable, view, or disable IGMP snooping, use the following commands. There is no specific configuration needed for IGMP snooping with virtual link trunking (VLT). For information about VLT configurations, refer to Virtual Link Trunking (VLT). • Enable IGMP snooping on a switch. CONFIGURATION mode ip igmp snooping enable • View the configuration. CONFIGURATION mode show running-config • Disable snooping on a VLAN. INTERFACE VLAN mode no ip igmp snooping Related Configuration Tasks • Specifying a Port as Connected to a Multicast Router • Removing a Group-Port Association • Disabling Multicast Flooding • Configuring the Switch as Querier Example of ip igmp snooping enable Command Dell(conf)#ip igmp snooping enable Dell(conf)#do show running-config igmp ip igmp snooping enable Dell(conf)# Removing a Group-Port Association To configure or view the remove a group-port association feature, use the following commands. • Configure the switch to remove a group-port association after receiving an IGMP Leave message. INTERFACE VLAN mode ip igmp fast-leave 454 Internet Group Management Protocol (IGMP)