Igmp Snooping Configuration Guidelines - Lenovo RackSwitch G8264 Application Manual

IGMP Snooping Configuration Guidelines

© Copyright Lenovo 2016
Consider the following guidelines when you configure IGMP Snooping:
 IGMP operation is independent of the routing method. You can use RIP, OSPF,
or static routes for Layer 3 routing.
 When multicast traffic flood is disabled, the multicast traffic sent by the
multicast server is discarded if no hosts or Mrouters are learned on the switch.
 The Mrouter periodically sends IGMP Queries.
The switch learns the Mrouter on the port connected to the router when it sees

Query messages. The switch then floods the IGMP queries on all other ports
including a LAG, if any.
Multicast hosts send IGMP Reports as a reply to the IGMP Queries sent by the

Mrouter.
The switch can also learn an Mrouter when it receives a PIM hello packet from

another device. However, an Mrouter learned from a PIM packet has a lower
priority than an Mrouter learned from an IGMP Query. A switch overwrites an
Mrouter learned from a PIM packet when it receives an IGMP Query on the
same port.
 A host sends an IGMP Leave message to its multicast group. The expiration
timer for this group is updated to 10 seconds. The Layer 3 switch sends IGMP
Group‐Specific Query to the host that had sent the Leave message. If the host
does not respond with an IGMP Report during these 10 seconds, all the groups
expire and the switch deletes the host from the IGMP groups table. The switch
then proxies the IGMP Leave messages to the Mrouter.
Chapter 32: Internet Group Management Protocol
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