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Configuring Layer 2 Multicast
2.2 Using the CLI
2.2.1 Configuring IGMP Snooping Globally
Follow these steps to configure IGMP Snooping globally:
Step 1
configure
Enter global configuration mode.
Step 2
ip igmp snooping
Enable IGMP Snooping Globally.
Step 3
ip igmp snooping version {v1 | v2 | v3}
Configure the IGMP version.
v1:The switch works as an IGMPv1 Snooping switch. It can only process IGMPv1 report
messages from the host. Report messages of other versions are ignored.
v2: The switch works as an IGMPv2 Snooping switch. It can process both IGMPv1 and IGMPv2
report messages from the host. IGMPv3 report messages are ignored.
v3: The switch works as an IGMPv3 Snooping switch. It can process IGMPv1, IGMPv2 and
IGMPv3 report messages from the host.
Step 4
ip igmp snooping drop-unknown
(Optional) Configure the way how the switch processes multicast streams that are sent to
unknown multicast groups as Discard. By default, it is Forward.
Unknown multicast groups are multicast groups that do not match any of the groups
announced in earlier IGMP membership reports, and thus cannot be found in the multicast
forwarding table of the switch.
Note:
need to ensure MLD Snooping is enabled globally. To enable MLD Snooping globally, use the
ipv6 mld snooping
Step 5
ip igmp snooping header-validation
(Optional) Enable header validation.
Generally, for IGMP packets, the TTL value should be 1, ToS field should be 0xC0, and Router
Alert option should be 0x94040000. The fields validated depend on the IGMP version being
used. IGMPv1 only checks the TTL field. IGMPv2 checks the TTL field and the Router Alert
option. IGMPv3 checks TTL field, ToS field and Router Alert option. Packets that fail the
validation process will be dropped.
Step 6
show ip igmp snooping
Show the basic IGMP Snooping configuration.
Step 7
end
Return to privileged EXEC mode.
Step 8
copy running-config startup-config
Save the settings in the configuration file.
IGMP Snooping and MLD Snooping share the setting of Unknown Multicast Groups, you
command in global configuration mode.
IGMP Snooping Configuration
User Guide
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