19-9
Cisco Nexus 1000V Troubleshooting Guide, Release 5.2(1)SV3(1.1)
OL-31593-01
Chapter 19 Multicast IGMP
Problems with Multicast IGMP Snooping
LTL 18 is also in multicast group 224.1.2.3, which means it is a VM and generates multicast traffic
to 224.1.2.3. The traffic is forwarded to vmnic3, which is the uplink to the upstream switch.
The multicast group table entry for 0.0.0.0 serves as a default route. If any multicast group traffic
does not match any of the multicast group, the address uses the default route, which means that the
traffic is forwarded to an upstream switch through vmnic3.
Problems with Multicast IGMP Snooping
The following are symptoms, possible causes, and solutions for problems with multicast IGMP
snooping.
Symptom Possible Causes Solution
A VM is interested in the
multicast traffic but is not
receiving the multicast
traffic.
—Use the debug ip igmp snooping vlan
command to determine if IGMP
snooping is working as expected.
Examine the output to see if the port is
receiving the IGMP report and if the
interface has been added to the
multicast traffic interface list for the
VM.
—Use the module vem module-number
execute vemcmd show vlan command
to verify that the multicast distribution
table in the VEM has the correct
information in it.
—Use the module vem module-number
execute vemcmd show port command
to see the port table. Make sure that the
table has the correct information in it.
Make sure that the state of the trunk
port and the access port is UP/UP.
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