The default SSM group address range is 232.0.0.0 to 232.255.255.255. An IGMP proxy device provides the SSM service for hosts only when it receives Report messages with group address in this range. Sometimes, the SSM group address range must be narrowed to ensure security of a multicast network, and sometimes, the SSM group address range needs to be expanded because the default SSM group addresses are insufficient. In these cases, configure an SSM group address range on IGMP proxy devices. Ensure that all the multicast devices on the network are configured with the same SSM group address range.