The figure above shows the scenario that multicast traffic does not flow to all ports in the networks. By following steps we can figure out why VCL client does not receive multicast traffic from VCL server.

Step 1. Check IGMP Snooping function and IGMP Snooping Running Status by the command "show ip igmp snooping".

Please note that IGMP Snooping functions only when IGMP Snooping is enabled and IGMP Running Status is active.

SW_1#show ip igmp snooping
IGMP Snooping                       : Enabled
 Router Port Expire Time            : 300 s
 Router Alert Check                 : Disabled
 Router Port Mode                   : Forward
 TCN Flood                          : Disabled
 TCN Query Solicit                  : Disabled
 Unregistered Data Flood            : Disabled
 802.1p Forwarding Priority         : Disabled
 Unsolicited Report Interval        : 400 s
 Version Exclusive                  : Disabled
 Version                            : 2
 Proxy Reporting                    : Disabled
 Querier                            : Disabled

 VLAN 1:
 --------
 IGMP Snooping                      : Enabled
 IGMP Snooping Running Status       : Inactive
 Version                            : Using global Version (2)
 Version Exclusive                  : Using global status (Disabled)
 Immediate Leave                    : Disabled
 Last Member Query Interval         : 10 (unit: 1/10s)
 Last Member Query Count            : 2
 General Query Suppression          : Disabled
 Query Interval                     : 125
 Query Response Interval            : 100 (unit: 1/10s)
 Proxy Query Address                : 0.0.0.0
 Proxy Reporting                    : Using global status (Disabled)
 Multicast Router Discovery         : Disabled

 VLAN Static Group    Port
 ---- --------------- --------

As shown in the configuration above, IGMP snooping function is enabled but IGMP Snooping Running Status is Inactive.

Step 2. Check Multicast router function in SW1 by the command "show ip igmp snooping mrouter".

SW_1#show ip igmp snooping mrouter
 VLAN M'cast Router Ports Type    Expire
 ---- ------------------- ------- --------

The configuration shows there is no any multicast router in SW1. It is necessary to have a Multicast Router to control IGMP. Multicast Router controls IGMP by sending out IGMP General Query periodically to solicit receivers who want to join the multicast group and sending Group Specific Query after receiving 'leave messages' to make sure any other receivers remains in that multicast group etc.

Step 3. Check if IP IGMP Snooping Group is grouped by Multicast router by the command "show ip igmp snooping group".

SW_1#show ip igmp snooping group
Bridge Multicast Forwarding Entry Count:1
Flag: R - Router port, M - Group member port
      H - Host counts (number of hosts join the group on this port).
      P - Port counts (number of ports join the group).
 Up time: Group elapsed time (d:h:m:s).
 Expire : Group remaining time (m:s).

VLAN Group           Port        Up time     Expire Count
---- --------------- ----------- ----------- ------ --------
   1 224.1.1.1                               01:00      0(P)