Igmp Snooping Configuration Guidelines - IBM RackSwitch G8000 Application Manual

IGMP Snooping Configuration Guidelines

© Copyright IBM Corp. 2011
By default, the G8000 snoops the first eight sources listed in the IGMPv3 Group
Record. Use the following command to change the number of snooping sources:
# ip igmp snoop igmpv3 sources <1-64>
RS G8000(config)
IGMPv3 Snooping is compatible with IGMPv1 and IGMPv2 Snooping. To disable
snooping on version 1 and version 2 reports, use the following command:
RS G8000(config) # no ip igmp snoop igmpv3 v1v2
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 for the VLANs.
• 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 Trunk Group, 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 IGMP timeout variable (the default is 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 the timeout interval, 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 19. Internet Group Management Protocol
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