level of conformance in multicast

I am working on a project that needs multicasting within the network (connected via ethernet)
But the host is able to only send multicast datagrams but unable to hear those sent by other hosts.
(The code works fine on other hosts)
How to resolve this issue?

How can we find the level of conformance of multicasting on a host?

How to upgrade the level from level1 to level2?

Thanks,
Spatika