I have connected three servers to Cisco Nexus 7000 switch.
Server1 send multicast packets, server2 subscribes to multicast packets and server3 is for the tests.
No matter if I subscribe to multicast from server2 or not all interfaces are flooded by multicast packets even I have had IGMP snooping enabled.
What is going on here???
This is my configuration:
switch(config-vlan)# show ip igmp snooping
Global IGMP Snooping Information:
IGMP Snooping enabled
Optimised Multicast Flood (OMF) enabled
IGMPv1/v2 Report Suppression enabled
IGMPv3 Report Suppression disabled
Link Local Groups Suppression enabled
VPC Multicast optimization disabled
Group timeout configured: never
IGMP Snooping information for vlan 1
IGMP snooping enabled
Lookup mode: IP
Optimised Multicast Flood (OMF) enabled
IGMP querier none
Switch-querier disabled
IGMPv3 Explicit tracking enabled
IGMPv2 Fast leave disabled
IGMPv1/v2 Report suppression enabled
IGMPv3 Report suppression disabled
Link Local Groups suppression enabled
Router port detection using PIM Hellos, IGMP Queries
Number of router-ports: 0
Number of groups: 1
VLAN vPC function disabled
Active ports:
Eth1/3 Eth1/5 Eth1/7
IGMP Snooping information for vlan 4045
IGMP snooping enabled
Lookup mode: IP
Optimised Multicast Flood (OMF) enabled
IGMP querier none
Switch-querier disabled
IGMPv3 Explicit tracking enabled
IGMPv2 Fast leave disabled
IGMPv1/v2 Report suppression enabled
IGMPv3 Report suppression disabled
Link Local Groups suppression enabled
Router port detection using PIM Hellos, IGMP Queries
Number of router-ports: 0
Number of groups: 0
VLAN vPC function disabled
Active ports:
switch(config-vlan)#
Best Answer
That was easy and embarrassing - we have been sending packets to multicast 225.0.0.1 and 239.0.0.1-16 which are multicast range without IGMP Snooping filtering, according to:
IETF specification: https://datatracker.ietf.org/doc/html/draft-ietf-mboned-ipv4-mcast-unusable-01
Cisco documentation (page 7-9): http://www.cisco.com/c/dam/en/us/support/docs/ip/ip-multicast/ipmlt_wp.pdf