> Hi Tim,
> 
> I do have  a problem using UDP multicast on en1 (one special interface of 2).
> I bound to a specific ip (en1) I can send multicast
> messages on each nic but I'm not able to receive multicast
> frames with this configuration anymore.
> 
> With wireshark I can see the IGMP multicast messages  (join and leave)
> and I can see the udp multicast frames on the net which should be received
> by en1 but the stack doesn't receive them.
> 
> I am going to post more details tomorrow including some sample
> code but I am still not sure if this is a problem
> 
> 1.in my code
> 2.within multicast managing of the nic driver
> 3.within the tcp/ip stack.
> 
> Could you please post  a sample code as well and describe
> the ip configuration you are using and what happens on the net
> 
> post the output of ifconfig and netstat -nr as well. I am going to 
> debug deeper into my problem it might be I find something 
> helpful for you as well.
> 
> regards,
>   Clemens

Hi all,
now I have written a simple test program which can be 
used to test receive and send of multicast packets

I am able to send in all 3 possible modes
(socket bound to ip of en0,en1 or to INADDR_ANY).

Tim, if I bind to different sockets the src address changes 
as well.

I am just able to receive multicast messages with 
INADDR_ANY configuration.

Looking into the documentation tells me it is not forbidden
and I should be able to do that but it doesn't work.

see the attached sample file

Does somebody have an idea, did I something wrong within
my code ?

regards,
   Clemens

Here is how I create the socket

	m_fdDMCPSock = ::socket(PF_INET, SOCK_DGRAM, 0);
	if ( m_fdDMCPSock == -1 )
	{
		// <<ERROR>>
		LOG_STD_ERROR("Failed to create a socket for DMCP processing.");
	}
	
	if ( m_fdDMCPSock != -1 )
	{
		int nRet = -1;

		int nOptVal = 1;
		nRet = ::setsockopt(m_fdDMCPSock,SOL_SOCKET,SO_BROADCAST,&nOptVal,sizeof(nOptVal));
		if ( nRet < 0 )
		{
			// <<ERROR>>
			LOG_STD_ERROR("Failed to set options for DMCP processing socket.");
			bRet = false; 
		}

		struct ifreq ifr;
		::strcpy(ifr.ifr_name,"en1");
		::ioctl(m_fdDMCPSock,SIOCGIFADDR,reinterpret_cast<int>(&ifr));
	
		nRet = ::setsockopt(m_fdDMCPSock,SOL_SOCKET,SO_BINDTODEVICE,&ifr,sizeof(ifr));
		if ( nRet < 0 )
		{
			// <<ERROR>>
			LOG_STD_ERROR("Failed to set options for DMCP processing socket.");
			bRet = false; 
		}		
	}


From that point on - I operate pretty normally.  Things are working fine for me now.

Tim